svn commit: r322119 - in stable/11/sys/dev: mmc sdhci

Marius Strobl marius at FreeBSD.org
Sun Aug 6 16:07:27 UTC 2017


Author: marius
Date: Sun Aug  6 16:07:25 2017
New Revision: 322119
URL: https://svnweb.freebsd.org/changeset/base/322119

Log:
  MFC: r319350, r321385, r321490, r321588, r321948
  
  o Use SDHCI_CAN_DRIVE_TYPE_{A,C,D} to check for driver type support in
    SDHCI_CAPABILITIES2 instead of SDHCI_CTRL2_DRIVER_TYPE_{A,C,D} which
    are meant for setting the driver type in SDHCI_HOST_CONTROL2.
  
  o Add support for eMMC HS200 and HS400 bus speed modes at 200 MHz to
    sdhci(4), mmc(4) and mmcsd(4).
  
    On the system where the addition of DDR52 support increased the read
    throughput to ~80 MB/s (from ~45 MB/s at high speed), HS200 yields
    ~154 MB/s and HS400 ~187 MB/s, i. e. performance now has more than
    quadrupled compared to pre-r315598 (pre-r318494 in stable/11).
  
    However, in fact this isn't a feature-only change; there are boards
    based on Intel Bay Trail where DDR52 is problematic and the suggested
    workaround is to use HS200 mode instead. So far exact details are
    unknown, however, i. e. whether that's due to a defect in these SoCs
    or on the boards.
  
    Moreover, due to the above changes requiring to be aware of possible
    MMC siblings in the fast path of mmc(4), corresponding information
    now is cached in mmc_softc. As a side-effect, mmc_calculate_clock(),
    now longer will trigger a panic in low memory situations and all of
    mmc(4) operate on the same set of child devices.
  
  o Fix a bug in the failure reporting of mmcsd_delete() that could lead
    to a panic.
  
  o Fix 2 bugs on resume, one in mmcsd(4) that could lead to a panic and
    another one in mmc(4) that could lead to devices no longer working.
  
  o Fix a memory leak in mmcsd_ioctl() in case copyin(9) fails. [1]
  
  o Fix missing variable initialization in mmc_switch_status(). [2]
  
  o Fix R1_SWITCH_ERROR detection in mmc_switch_status(). [3]
  
  o Handle the case of device_add_child(9) failing, for example due to
    a memory shortage, gracefully in mmc(4) and sdhci(4), including not
    leaking memory for the instance variables in case of mmc(4), also
    fixing [4].
  
  o Correctly use the size of a pointer rather than that of a pointer to
    a pointer (this bug was present in head r321385 only, i. e. not in a
    stable branch). [5]
  
  o Handle the case of an unknown SD CSD version in mmc_decode_csd_sd()
    gracefully instead of calling panic(9).
  
  o Again, check and handle the return values of some additional function
    calls in mmc(4) instead of assuming that everything went right or mark
    non-fatal errors by casting the return value to void.
  
  o Correct a typo in the Linux IOCTL compatibility; it should have been
    MMC_IOC_MULTI_CMD rather than MMC_IOC_CMD_MULTI.
  
  o Now that we are reaching ever faster speeds (more improvement in this
    regard is to be expected when adding ADMA support to sdhci(4)), apply
    a few micro-optimizations to mmc(4), mmcsd(4) and sdhci(4).
  
  o Correct confusing and error prone mix-ups between "br" or "bridge" in
    mmc(4) and mmcsd(4) where - according to the terminology outlined in
    comments of bridge.h and mmcbr_if.m around since their addition in
    r163516 - the bus is meant and used instead.
  
  o Remove comment lines from bridge.h incorrectly suggesting that there
    would be a MMC bridge base class driver.
  
  o Update comments in bridge.h regarding the star topology of SD and SDIO;
    since version 3.00 of the SDHCI specification, for eSD and eSDIO bus
    topologies are actually possible in form of so called "shared buses"
    (in some subcontext later on renamed to "embedded" buses).
  
  Reported by:	Coverity
  CID:		1372612 [1], 1372624 [2], 1372594 [3], 1007069 [4],
  		1378432 [5]

Modified:
  stable/11/sys/dev/mmc/bridge.h
  stable/11/sys/dev/mmc/mmc.c
  stable/11/sys/dev/mmc/mmc_ioctl.h
  stable/11/sys/dev/mmc/mmc_private.h
  stable/11/sys/dev/mmc/mmc_subr.c
  stable/11/sys/dev/mmc/mmc_subr.h
  stable/11/sys/dev/mmc/mmcbr_if.m
  stable/11/sys/dev/mmc/mmcbrvar.h
  stable/11/sys/dev/mmc/mmcbus_if.m
  stable/11/sys/dev/mmc/mmcreg.h
  stable/11/sys/dev/mmc/mmcsd.c
  stable/11/sys/dev/sdhci/sdhci.c
  stable/11/sys/dev/sdhci/sdhci.h
  stable/11/sys/dev/sdhci/sdhci_acpi.c
  stable/11/sys/dev/sdhci/sdhci_if.m
  stable/11/sys/dev/sdhci/sdhci_pci.c
Directory Properties:
  stable/11/   (props changed)

Modified: stable/11/sys/dev/mmc/bridge.h
==============================================================================
--- stable/11/sys/dev/mmc/bridge.h	Sun Aug  6 12:27:20 2017	(r322118)
+++ stable/11/sys/dev/mmc/bridge.h	Sun Aug  6 16:07:25 2017	(r322119)
@@ -65,12 +65,10 @@
  * linux/mmc/host.h file.
  *
  * A mmc bridge is a chipset that can have one or more mmc and/or sd
- * cards attached to it.  mmc cards are attached on a bus topology,
- * while sd and sdio cards are attached using a star topology (meaning
- * in practice each sd card has its own, independent slot).  Each
- * mmcbr is assumed to be derived from the mmcbr.  This is done to
- * allow for easier addition of bridges (as each bridge does not need
- * to be added to the mmcbus file).
+ * cards attached to it.  mmc devices are attached on a bus topology,
+ * while sd and sdio cards usually are attached using a star topology
+ * (meaning in practice each sd card has its own, independent slot).
+ * Since SDHCI v3.00, buses for esd and esdio are possible, though.
  *
  * Attached to the mmc bridge is an mmcbus.  The mmcbus is described
  * in dev/mmc/mmcbus_if.m.
@@ -137,6 +135,10 @@ enum mmc_card_mode {
 	mode_mmc, mode_sd
 };
 
+enum mmc_retune_req {
+	retune_req_none = 0, retune_req_normal, retune_req_reset
+};
+
 struct mmc_host {
 	int f_min;
 	int f_max;
@@ -177,7 +179,7 @@ struct mmc_host {
 extern driver_t   mmc_driver;
 extern devclass_t mmc_devclass;
 
-#define	MMC_VERSION	3
+#define	MMC_VERSION	4
 
 #define	MMC_DECLARE_BRIDGE(name)					\
     DRIVER_MODULE(mmc, name, mmc_driver, mmc_devclass, NULL, NULL);	\

Modified: stable/11/sys/dev/mmc/mmc.c
==============================================================================
--- stable/11/sys/dev/mmc/mmc.c	Sun Aug  6 12:27:20 2017	(r322118)
+++ stable/11/sys/dev/mmc/mmc.c	Sun Aug  6 16:07:25 2017	(r322119)
@@ -88,14 +88,14 @@ struct mmc_ivars {
 	uint8_t raw_ext_csd[MMC_EXTCSD_SIZE]; /* Raw bits of the EXT_CSD */
 	uint32_t raw_sd_status[16];	/* Raw bits of the SD_STATUS */
 	uint16_t rca;
+	u_char read_only;	/* True when the device is read-only */
+	u_char high_cap;	/* High Capacity device (block addressed) */
 	enum mmc_card_mode mode;
+	enum mmc_bus_width bus_width;	/* Bus width to use */
 	struct mmc_cid cid;	/* cid decoded */
 	struct mmc_csd csd;	/* csd decoded */
 	struct mmc_scr scr;	/* scr decoded */
 	struct mmc_sd_status sd_status;	/* SD_STATUS decoded */
-	u_char read_only;	/* True when the device is read-only */
-	u_char bus_width;	/* Bus width to use */
-	u_char high_cap;	/* High Capacity card (block addressed) */
 	uint32_t sec_count;	/* Card capacity in 512byte blocks */
 	uint32_t timings;	/* Mask of bus timings supported */
 	uint32_t vccq_120;	/* Mask of bus timings at VCCQ of 1.2 V */
@@ -127,8 +127,10 @@ static int mmc_read_ivar(device_t bus, device_t child,
     uintptr_t *result);
 static int mmc_release_bus(device_t busdev, device_t dev);
 static int mmc_resume(device_t dev);
+static void mmc_retune_pause(device_t busdev, device_t dev, bool retune);
+static void mmc_retune_unpause(device_t busdev, device_t dev);
 static int mmc_suspend(device_t dev);
-static int mmc_wait_for_request(device_t brdev, device_t reqdev,
+static int mmc_wait_for_request(device_t busdev, device_t dev,
     struct mmc_request *req);
 static int mmc_write_ivar(device_t bus, device_t child, int which,
     uintptr_t value);
@@ -155,21 +157,23 @@ static void mmc_decode_cid_mmc(uint32_t *raw_cid, stru
     bool is_4_41p);
 static void mmc_decode_cid_sd(uint32_t *raw_cid, struct mmc_cid *cid);
 static void mmc_decode_csd_mmc(uint32_t *raw_csd, struct mmc_csd *csd);
-static void mmc_decode_csd_sd(uint32_t *raw_csd, struct mmc_csd *csd);
+static int mmc_decode_csd_sd(uint32_t *raw_csd, struct mmc_csd *csd);
 static void mmc_delayed_attach(void *xsc);
-static int mmc_delete_cards(struct mmc_softc *sc);
+static int mmc_delete_cards(struct mmc_softc *sc, bool final);
 static void mmc_discover_cards(struct mmc_softc *sc);
 static void mmc_format_card_id_string(struct mmc_ivars *ivar);
 static void mmc_go_discovery(struct mmc_softc *sc);
 static uint32_t mmc_get_bits(uint32_t *bits, int bit_len, int start,
     int size);
 static int mmc_highest_voltage(uint32_t ocr);
+static bool mmc_host_timing(device_t dev, enum mmc_bus_timing timing);
 static void mmc_idle_cards(struct mmc_softc *sc);
 static void mmc_ms_delay(int ms);
 static void mmc_log_card(device_t dev, struct mmc_ivars *ivar, int newcard);
 static void mmc_power_down(struct mmc_softc *sc);
 static void mmc_power_up(struct mmc_softc *sc);
 static void mmc_rescan_cards(struct mmc_softc *sc);
+static int mmc_retune(device_t busdev, device_t dev, bool reset);
 static void mmc_scan(struct mmc_softc *sc);
 static int mmc_sd_switch(struct mmc_softc *sc, uint8_t mode, uint8_t grp,
     uint8_t value, uint8_t *res);
@@ -183,15 +187,23 @@ static int mmc_send_op_cond(struct mmc_softc *sc, uint
     uint32_t *rocr);
 static int mmc_send_relative_addr(struct mmc_softc *sc, uint32_t *resp);
 static int mmc_set_blocklen(struct mmc_softc *sc, uint32_t len);
-static int mmc_set_card_bus_width(struct mmc_softc *sc, struct mmc_ivars *ivar);
+static int mmc_set_card_bus_width(struct mmc_softc *sc, struct mmc_ivars *ivar,
+    enum mmc_bus_timing timing);
 static int mmc_set_power_class(struct mmc_softc *sc, struct mmc_ivars *ivar);
 static int mmc_set_relative_addr(struct mmc_softc *sc, uint16_t resp);
 static int mmc_set_timing(struct mmc_softc *sc, struct mmc_ivars *ivar,
     enum mmc_bus_timing timing);
+static int mmc_set_vccq(struct mmc_softc *sc, struct mmc_ivars *ivar,
+    enum mmc_bus_timing timing);
+static int mmc_switch_to_hs200(struct mmc_softc *sc, struct mmc_ivars *ivar,
+    uint32_t clock);
+static int mmc_switch_to_hs400(struct mmc_softc *sc, struct mmc_ivars *ivar,
+    uint32_t max_dtr, enum mmc_bus_timing max_timing);
 static int mmc_test_bus_width(struct mmc_softc *sc);
 static uint32_t mmc_timing_to_dtr(struct mmc_ivars *ivar,
     enum mmc_bus_timing timing);
 static const char *mmc_timing_to_string(enum mmc_bus_timing timing);
+static void mmc_update_child_list(struct mmc_softc *sc);
 static int mmc_wait_for_command(struct mmc_softc *sc, uint32_t opcode,
     uint32_t arg, uint32_t flags, uint32_t *resp, int retries);
 static int mmc_wait_for_req(struct mmc_softc *sc, struct mmc_request *req);
@@ -235,7 +247,8 @@ mmc_detach(device_t dev)
 	struct mmc_softc *sc = device_get_softc(dev);
 	int err;
 
-	if ((err = mmc_delete_cards(sc)) != 0)
+	err = mmc_delete_cards(sc, true);
+	if (err != 0)
 		return (err);
 	mmc_power_down(sc);
 	MMC_LOCK_DESTROY(sc);
@@ -250,10 +263,21 @@ mmc_suspend(device_t dev)
 	int err;
 
 	err = bus_generic_suspend(dev);
-	if (err)
+	if (err != 0)
 		return (err);
+	/*
+	 * We power down with the bus acquired here, mainly so that no device
+	 * is selected any longer and sc->last_rca gets set to 0.  Otherwise,
+	 * the deselect as part of the bus acquisition in mmc_scan() may fail
+	 * during resume, as the bus isn't powered up again before later in
+	 * mmc_go_discovery().
+	 */
+	err = mmc_acquire_bus(dev, dev);
+	if (err != 0)
+		return (err);
 	mmc_power_down(sc);
-	return (0);
+	err = mmc_release_bus(dev, dev);
+	return (err);
 }
 
 static int
@@ -270,7 +294,8 @@ mmc_acquire_bus(device_t busdev, device_t dev)
 {
 	struct mmc_softc *sc;
 	struct mmc_ivars *ivar;
-	int err, rca;
+	int err;
+	uint16_t rca;
 	enum mmc_bus_timing timing;
 
 	err = MMCBR_ACQUIRE_HOST(device_get_parent(busdev), busdev);
@@ -294,12 +319,27 @@ mmc_acquire_bus(device_t busdev, device_t dev)
 		rca = ivar->rca;
 		if (sc->last_rca != rca) {
 			if (mmc_select_card(sc, rca) != MMC_ERR_NONE) {
-				device_printf(sc->dev, "Card at relative "
-				    "address %d failed to select.\n", rca);
+				device_printf(busdev, "Card at relative "
+				    "address %d failed to select\n", rca);
 				return (ENXIO);
 			}
 			sc->last_rca = rca;
 			timing = mmcbr_get_timing(busdev);
+			/*
+			 * For eMMC modes, setting/updating bus width and VCCQ
+			 * only really is necessary if there actually is more
+			 * than one device on the bus as generally that already
+			 * had to be done by mmc_calculate_clock() or one of
+			 * its calees.  Moreover, setting the bus width anew
+			 * can trigger re-tuning (via a CRC error on the next
+			 * CMD), even if not switching between devices an the
+			 * previously selected one is still tuned.  Obviously,
+			 * we need to re-tune the host controller if devices
+			 * are actually switched, though.
+			 */
+			if (timing >= bus_timing_mmc_ddr52 &&
+			    sc->child_count == 1)
+				return (0);
 			/* Prepare bus width for the new card. */
 			if (bootverbose || mmc_debug) {
 				device_printf(busdev,
@@ -308,38 +348,34 @@ mmc_acquire_bus(device_t busdev, device_t dev)
 				    (ivar->bus_width == bus_width_8) ? 8 : 1,
 				    mmc_timing_to_string(timing));
 			}
-			if (mmc_set_card_bus_width(sc, ivar) != MMC_ERR_NONE) {
-				device_printf(sc->dev, "Card at relative "
-				    "address %d failed to set bus width.\n",
+			if (mmc_set_card_bus_width(sc, ivar, timing) !=
+			    MMC_ERR_NONE) {
+				device_printf(busdev, "Card at relative "
+				    "address %d failed to set bus width\n",
 				    rca);
 				return (ENXIO);
 			}
-			if (isset(&ivar->vccq_120, timing))
-				mmcbr_set_vccq(busdev, vccq_120);
-			else if (isset(&ivar->vccq_180, timing))
-				mmcbr_set_vccq(busdev, vccq_180);
-			else
-				mmcbr_set_vccq(busdev, vccq_330);
-			if (mmcbr_switch_vccq(busdev) != 0) {
-				device_printf(sc->dev, "Failed to set VCCQ "
-				    "for card at relative address %d.\n", rca);
+			mmcbr_set_bus_width(busdev, ivar->bus_width);
+			mmcbr_update_ios(busdev);
+			if (mmc_set_vccq(sc, ivar, timing) != MMC_ERR_NONE) {
+				device_printf(busdev, "Failed to set VCCQ "
+				    "for card at relative address %d\n", rca);
 				return (ENXIO);
 			}
-			if (mmc_set_power_class(sc, ivar) != MMC_ERR_NONE) {
-				device_printf(sc->dev, "Card at relative "
-				    "address %d failed to set power class.\n",
-				    rca);
+			if (timing >= bus_timing_mmc_hs200 &&
+			    mmc_retune(busdev, dev, true) != 0) {
+				device_printf(busdev, "Card at relative "
+				    "address %d failed to re-tune\n", rca);
 				return (ENXIO);
 			}
-			mmcbr_set_bus_width(busdev, ivar->bus_width);
-			mmcbr_update_ios(busdev);
 		}
 	} else {
 		/*
 		 * If there's a card selected, stand down.
 		 */
 		if (sc->last_rca != 0) {
-			mmc_select_card(sc, 0);
+			if (mmc_select_card(sc, 0) != MMC_ERR_NONE)
+				return (ENXIO);
 			sc->last_rca = 0;
 		}
 	}
@@ -407,7 +443,7 @@ mmc_wait_for_req(struct mmc_softc *sc, struct mmc_requ
 
 	req->done = mmc_wakeup;
 	req->done_data = sc;
-	if (mmc_debug > 1) {
+	if (__predict_false(mmc_debug > 1)) {
 		device_printf(sc->dev, "REQUEST: CMD%d arg %#x flags %#x",
 		    req->cmd->opcode, req->cmd->arg, req->cmd->flags);
 		if (req->cmd->data) {
@@ -420,18 +456,66 @@ mmc_wait_for_req(struct mmc_softc *sc, struct mmc_requ
 	while ((req->flags & MMC_REQ_DONE) == 0)
 		msleep(req, &sc->sc_mtx, 0, "mmcreq", 0);
 	MMC_UNLOCK(sc);
-	if (mmc_debug > 2 || (mmc_debug > 0 && req->cmd->error != MMC_ERR_NONE))
+	if (__predict_false(mmc_debug > 2 || (mmc_debug > 0 &&
+	    req->cmd->error != MMC_ERR_NONE)))
 		device_printf(sc->dev, "CMD%d RESULT: %d\n",
 		    req->cmd->opcode, req->cmd->error);
 	return (0);
 }
 
 static int
-mmc_wait_for_request(device_t brdev, device_t reqdev __unused,
-    struct mmc_request *req)
+mmc_wait_for_request(device_t busdev, device_t dev, struct mmc_request *req)
 {
-	struct mmc_softc *sc = device_get_softc(brdev);
+	struct mmc_softc *sc;
+	struct mmc_ivars *ivar;
+	int err, i;
+	enum mmc_retune_req retune_req;
 
+	sc = device_get_softc(busdev);
+	KASSERT(sc->owner != NULL,
+	    ("%s: Request from %s without bus being acquired.", __func__,
+	    device_get_nameunit(dev)));
+
+	/*
+	 * Unless no device is selected or re-tuning is already ongoing,
+	 * execute re-tuning if a) the bridge is requesting to do so and
+	 * re-tuning hasn't been otherwise paused, or b) if a child asked
+	 * to be re-tuned prior to pausing (see also mmc_retune_pause()).
+	 */
+	if (__predict_false(sc->last_rca != 0 && sc->retune_ongoing == 0 &&
+	    (((retune_req = mmcbr_get_retune_req(busdev)) != retune_req_none &&
+	    sc->retune_paused == 0) || sc->retune_needed == 1))) {
+		if (__predict_false(mmc_debug > 1)) {
+			device_printf(busdev,
+			    "Re-tuning with%s circuit reset required\n",
+			    retune_req == retune_req_reset ? "" : "out");
+		}
+		if (device_get_parent(dev) == busdev)
+			ivar = device_get_ivars(dev);
+		else {
+			for (i = 0; i < sc->child_count; i++) {
+				ivar = device_get_ivars(sc->child_list[i]);
+				if (ivar->rca == sc->last_rca)
+					break;
+			}
+			if (ivar->rca != sc->last_rca)
+				return (EINVAL);
+		}
+		sc->retune_ongoing = 1;
+		err = mmc_retune(busdev, dev, retune_req == retune_req_reset);
+		sc->retune_ongoing = 0;
+		switch (err) {
+		case MMC_ERR_NONE:
+		case MMC_ERR_FAILED:	/* Re-tune error but still might work */
+			break;
+		case MMC_ERR_BADCRC:	/* Switch failure on HS400 recovery */
+			return (ENXIO);
+		case MMC_ERR_INVALID:	/* Driver implementation b0rken */
+		default:		/* Unknown error, should not happen */
+			return (EINVAL);
+		}
+		sc->retune_needed = 0;
+	}
 	return (mmc_wait_for_req(sc, req));
 }
 
@@ -599,11 +683,14 @@ mmc_power_down(struct mmc_softc *sc)
 static int
 mmc_select_card(struct mmc_softc *sc, uint16_t rca)
 {
-	int flags;
+	int err, flags;
 
 	flags = (rca ? MMC_RSP_R1B : MMC_RSP_NONE) | MMC_CMD_AC;
-	return (mmc_wait_for_command(sc, MMC_SELECT_CARD, (uint32_t)rca << 16,
-	    flags, NULL, CMD_RETRIES));
+	sc->retune_paused++;
+	err = mmc_wait_for_command(sc, MMC_SELECT_CARD, (uint32_t)rca << 16,
+	    flags, NULL, CMD_RETRIES);
+	sc->retune_paused--;
+	return (err);
 }
 
 static int
@@ -635,7 +722,8 @@ mmc_sd_switch(struct mmc_softc *sc, uint8_t mode, uint
 }
 
 static int
-mmc_set_card_bus_width(struct mmc_softc *sc, struct mmc_ivars *ivar)
+mmc_set_card_bus_width(struct mmc_softc *sc, struct mmc_ivars *ivar,
+    enum mmc_bus_timing timing)
 {
 	struct mmc_command cmd;
 	int err;
@@ -668,28 +756,33 @@ mmc_set_card_bus_width(struct mmc_softc *sc, struct mm
 	} else {
 		switch (ivar->bus_width) {
 		case bus_width_1:
+			if (timing == bus_timing_mmc_hs400 ||
+			    timing == bus_timing_mmc_hs400es)
+				return (MMC_ERR_INVALID);
 			value = EXT_CSD_BUS_WIDTH_1;
 			break;
 		case bus_width_4:
-			switch (mmcbr_get_timing(sc->dev)) {
+			switch (timing) {
 			case bus_timing_mmc_ddr52:
-			case bus_timing_mmc_hs200:
-			case bus_timing_mmc_hs400:
-			case bus_timing_mmc_hs400es:
 				value = EXT_CSD_BUS_WIDTH_4_DDR;
 				break;
+			case bus_timing_mmc_hs400:
+			case bus_timing_mmc_hs400es:
+				return (MMC_ERR_INVALID);
 			default:
 				value = EXT_CSD_BUS_WIDTH_4;
 				break;
 			}
 			break;
 		case bus_width_8:
-			switch (mmcbr_get_timing(sc->dev)) {
+			value = 0;
+			switch (timing) {
+			case bus_timing_mmc_hs400es:
+				value = EXT_CSD_BUS_WIDTH_ES;
+				/* FALLTHROUGH */
 			case bus_timing_mmc_ddr52:
-			case bus_timing_mmc_hs200:
 			case bus_timing_mmc_hs400:
-			case bus_timing_mmc_hs400es:
-				value = EXT_CSD_BUS_WIDTH_8_DDR;
+				value |= EXT_CSD_BUS_WIDTH_8_DDR;
 				break;
 			default:
 				value = EXT_CSD_BUS_WIDTH_8;
@@ -814,6 +907,13 @@ mmc_set_timing(struct mmc_softc *sc, struct mmc_ivars 
 		case bus_timing_mmc_ddr52:
 			value = EXT_CSD_HS_TIMING_HS;
 			break;
+		case bus_timing_mmc_hs200:
+			value = EXT_CSD_HS_TIMING_HS200;
+			break;
+		case bus_timing_mmc_hs400:
+		case bus_timing_mmc_hs400es:
+			value = EXT_CSD_HS_TIMING_HS400;
+			break;
 		default:
 			return (MMC_ERR_INVALID);
 		}
@@ -830,6 +930,23 @@ mmc_set_timing(struct mmc_softc *sc, struct mmc_ivars 
 	return (err);
 }
 
+static int
+mmc_set_vccq(struct mmc_softc *sc, struct mmc_ivars *ivar,
+    enum mmc_bus_timing timing)
+{
+
+	if (isset(&ivar->vccq_120, timing))
+		mmcbr_set_vccq(sc->dev, vccq_120);
+	else if (isset(&ivar->vccq_180, timing))
+		mmcbr_set_vccq(sc->dev, vccq_180);
+	else
+		mmcbr_set_vccq(sc->dev, vccq_330);
+	if (mmcbr_switch_vccq(sc->dev) != 0)
+		return (MMC_ERR_INVALID);
+	else
+		return (MMC_ERR_NONE);
+}
+
 static const uint8_t p8[8] = {
 	0x55, 0xAA, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
 };
@@ -1037,7 +1154,7 @@ static const int cur_max[8] = {
 	1000, 5000, 10000, 25000, 35000, 45000, 800000, 200000
 };
 
-static void
+static int
 mmc_decode_csd_sd(uint32_t *raw_csd, struct mmc_csd *csd)
 {
 	int v;
@@ -1078,6 +1195,7 @@ mmc_decode_csd_sd(uint32_t *raw_csd, struct mmc_csd *c
 		csd->r2w_factor = 1 << mmc_get_bits(raw_csd, 128, 26, 3);
 		csd->write_bl_len = 1 << mmc_get_bits(raw_csd, 128, 22, 4);
 		csd->write_bl_partial = mmc_get_bits(raw_csd, 128, 21, 1);
+		return (MMC_ERR_NONE);
 	} else if (v == 1) {
 		m = mmc_get_bits(raw_csd, 128, 115, 4);
 		e = mmc_get_bits(raw_csd, 128, 112, 3);
@@ -1101,8 +1219,9 @@ mmc_decode_csd_sd(uint32_t *raw_csd, struct mmc_csd *c
 		csd->r2w_factor = 1 << mmc_get_bits(raw_csd, 128, 26, 3);
 		csd->write_bl_len = 1 << mmc_get_bits(raw_csd, 128, 22, 4);
 		csd->write_bl_partial = mmc_get_bits(raw_csd, 128, 21, 1);
-	} else
-		panic("unknown SD CSD version");
+		return (MMC_ERR_NONE);
+	}
+	return (MMC_ERR_INVALID);
 }
 
 static void
@@ -1366,6 +1485,53 @@ mmc_timing_to_string(enum mmc_bus_timing timing)
 	return ("");
 }
 
+static bool
+mmc_host_timing(device_t dev, enum mmc_bus_timing timing)
+{
+	int host_caps;
+
+	host_caps = mmcbr_get_caps(dev);
+
+#define	HOST_TIMING_CAP(host_caps, cap) ({				\
+	bool retval;							\
+	if (((host_caps) & (cap)) == (cap))				\
+		retval = true;						\
+	else								\
+		retval = false;						\
+	retval;								\
+})
+
+	switch (timing) {
+	case bus_timing_normal:
+		return (true);
+	case bus_timing_hs:
+		return (HOST_TIMING_CAP(host_caps, MMC_CAP_HSPEED));
+	case bus_timing_uhs_sdr12:
+		return (HOST_TIMING_CAP(host_caps, MMC_CAP_UHS_SDR12));
+	case bus_timing_uhs_sdr25:
+		return (HOST_TIMING_CAP(host_caps, MMC_CAP_UHS_SDR25));
+	case bus_timing_uhs_ddr50:
+		return (HOST_TIMING_CAP(host_caps, MMC_CAP_UHS_DDR50));
+	case bus_timing_uhs_sdr50:
+		return (HOST_TIMING_CAP(host_caps, MMC_CAP_UHS_SDR50));
+	case bus_timing_uhs_sdr104:
+		return (HOST_TIMING_CAP(host_caps, MMC_CAP_UHS_SDR104));
+	case bus_timing_mmc_ddr52:
+		return (HOST_TIMING_CAP(host_caps, MMC_CAP_MMC_DDR52));
+	case bus_timing_mmc_hs200:
+		return (HOST_TIMING_CAP(host_caps, MMC_CAP_MMC_HS200));
+	case bus_timing_mmc_hs400:
+		return (HOST_TIMING_CAP(host_caps, MMC_CAP_MMC_HS400));
+	case bus_timing_mmc_hs400es:
+		return (HOST_TIMING_CAP(host_caps, MMC_CAP_MMC_HS400 |
+		    MMC_CAP_MMC_ENH_STROBE));
+	}
+
+#undef HOST_TIMING_CAP
+
+	return (false);
+}
+
 static void
 mmc_log_card(device_t dev, struct mmc_ivars *ivar, int newcard)
 {
@@ -1397,9 +1563,8 @@ mmc_discover_cards(struct mmc_softc *sc)
 	u_char switch_res[64];
 	uint32_t raw_cid[4];
 	struct mmc_ivars *ivar = NULL;
-	device_t *devlist;
 	device_t child;
-	int devcount, err, host_caps, i, newcard;
+	int err, host_caps, i, newcard;
 	uint32_t resp, sec_count, status;
 	uint16_t rca = 2;
 
@@ -1407,6 +1572,7 @@ mmc_discover_cards(struct mmc_softc *sc)
 	if (bootverbose || mmc_debug)
 		device_printf(sc->dev, "Probing cards\n");
 	while (1) {
+		child = NULL;
 		sc->squelched++; /* Errors are expected, squelch reporting. */
 		err = mmc_all_send_cid(sc, raw_cid);
 		sc->squelched--;
@@ -1417,18 +1583,14 @@ mmc_discover_cards(struct mmc_softc *sc)
 			break;
 		}
 		newcard = 1;
-		if ((err = device_get_children(sc->dev, &devlist,
-		    &devcount)) != 0)
-			return;
-		for (i = 0; i < devcount; i++) {
-			ivar = device_get_ivars(devlist[i]);
+		for (i = 0; i < sc->child_count; i++) {
+			ivar = device_get_ivars(sc->child_list[i]);
 			if (memcmp(ivar->raw_cid, raw_cid, sizeof(raw_cid)) ==
 			    0) {
 				newcard = 0;
 				break;
 			}
 		}
-		free(devlist, M_TEMP);
 		if (bootverbose || mmc_debug) {
 			device_printf(sc->dev,
 			    "%sard detected (CID %08x%08x%08x%08x)\n",
@@ -1451,7 +1613,7 @@ mmc_discover_cards(struct mmc_softc *sc)
 			if (err != MMC_ERR_NONE) {
 				device_printf(sc->dev,
 				    "Error getting RCA %d\n", err);
-				break;
+				goto free_ivar;
 			}
 			ivar->rca = resp >> 16;
 			/* Get card CSD. */
@@ -1459,7 +1621,7 @@ mmc_discover_cards(struct mmc_softc *sc)
 			if (err != MMC_ERR_NONE) {
 				device_printf(sc->dev,
 				    "Error getting CSD %d\n", err);
-				break;
+				goto free_ivar;
 			}
 			if (bootverbose || mmc_debug)
 				device_printf(sc->dev,
@@ -1467,7 +1629,11 @@ mmc_discover_cards(struct mmc_softc *sc)
 				    newcard ? "New c" : "C", ivar->raw_csd[0],
 				    ivar->raw_csd[1], ivar->raw_csd[2],
 				    ivar->raw_csd[3]);
-			mmc_decode_csd_sd(ivar->raw_csd, &ivar->csd);
+			err = mmc_decode_csd_sd(ivar->raw_csd, &ivar->csd);
+			if (err != MMC_ERR_NONE) {
+				device_printf(sc->dev, "Error decoding CSD\n");
+				goto free_ivar;
+			}
 			ivar->sec_count = ivar->csd.capacity / MMC_SECTOR_SIZE;
 			if (ivar->csd.csd_structure > 0)
 				ivar->high_cap = 1;
@@ -1480,12 +1646,12 @@ mmc_discover_cards(struct mmc_softc *sc)
 			if (err != MMC_ERR_NONE) {
 				device_printf(sc->dev,
 				    "Error reading card status %d\n", err);
-				break;
+				goto free_ivar;
 			}
 			if ((status & R1_CARD_IS_LOCKED) != 0) {
 				device_printf(sc->dev,
-				    "Card is password protected, skipping.\n");
-				break;
+				    "Card is password protected, skipping\n");
+				goto free_ivar;
 			}
 
 			/* Get card SCR.  Card must be selected to fetch it. */
@@ -1493,13 +1659,13 @@ mmc_discover_cards(struct mmc_softc *sc)
 			if (err != MMC_ERR_NONE) {
 				device_printf(sc->dev,
 				    "Error selecting card %d\n", err);
-				break;
+				goto free_ivar;
 			}
 			err = mmc_app_send_scr(sc, ivar->rca, ivar->raw_scr);
 			if (err != MMC_ERR_NONE) {
 				device_printf(sc->dev,
 				    "Error reading SCR %d\n", err);
-				break;
+				goto free_ivar;
 			}
 			mmc_app_decode_scr(ivar->raw_scr, &ivar->scr);
 			/* Get card switch capabilities (command class 10). */
@@ -1527,7 +1693,7 @@ mmc_discover_cards(struct mmc_softc *sc)
 			 * use from the sd_status is the erase sector size, but
 			 * it is still nice to get that right.
 			 */
-			mmc_select_card(sc, 0);
+			(void)mmc_select_card(sc, 0);
 			(void)mmc_select_card(sc, ivar->rca);
 			(void)mmc_app_sd_status(sc, ivar->rca,
 			    ivar->raw_sd_status);
@@ -1537,47 +1703,24 @@ mmc_discover_cards(struct mmc_softc *sc)
 				ivar->erase_sector =
 				    16 << ivar->sd_status.au_size;
 			}
-			/* Find max supported bus width. */
+			/* Find maximum supported bus width. */
 			if ((host_caps & MMC_CAP_4_BIT_DATA) &&
 			    (ivar->scr.bus_widths & SD_SCR_BUS_WIDTH_4))
 				ivar->bus_width = bus_width_4;
 
-			/*
-			 * Some cards that report maximum I/O block sizes
-			 * greater than 512 require the block length to be
-			 * set to 512, even though that is supposed to be
-			 * the default.  Example:
-			 *
-			 * Transcend 2GB SDSC card, CID:
-			 * mid=0x1b oid=0x534d pnm="00000" prv=1.0 mdt=00.2000
-			 */
-			if (ivar->csd.read_bl_len != MMC_SECTOR_SIZE ||
-			    ivar->csd.write_bl_len != MMC_SECTOR_SIZE)
-				mmc_set_blocklen(sc, MMC_SECTOR_SIZE);
-
-			mmc_format_card_id_string(ivar);
-
-			if (bootverbose || mmc_debug)
-				mmc_log_card(sc->dev, ivar, newcard);
-			if (newcard) {
-				/* Add device. */
-				child = device_add_child(sc->dev, NULL, -1);
-				device_set_ivars(child, ivar);
-			}
-			mmc_select_card(sc, 0);
-			return;
+			goto child_common;
 		}
 		ivar->rca = rca++;
 		err = mmc_set_relative_addr(sc, ivar->rca);
 		if (err != MMC_ERR_NONE) {
 			device_printf(sc->dev, "Error setting RCA %d\n", err);
-			break;
+			goto free_ivar;
 		}
 		/* Get card CSD. */
 		err = mmc_send_csd(sc, ivar->rca, ivar->raw_csd);
 		if (err != MMC_ERR_NONE) {
 			device_printf(sc->dev, "Error getting CSD %d\n", err);
-			break;
+			goto free_ivar;
 		}
 		if (bootverbose || mmc_debug)
 			device_printf(sc->dev,
@@ -1596,19 +1739,19 @@ mmc_discover_cards(struct mmc_softc *sc)
 		if (err != MMC_ERR_NONE) {
 			device_printf(sc->dev,
 			    "Error reading card status %d\n", err);
-			break;
+			goto free_ivar;
 		}
 		if ((status & R1_CARD_IS_LOCKED) != 0) {
 			device_printf(sc->dev,
-			    "Card is password protected, skipping.\n");
-			break;
+			    "Card is password protected, skipping\n");
+			goto free_ivar;
 		}
 
 		err = mmc_select_card(sc, ivar->rca);
 		if (err != MMC_ERR_NONE) {
 			device_printf(sc->dev, "Error selecting card %d\n",
 			    err);
-			break;
+			goto free_ivar;
 		}
 
 		/* Only MMC >= 4.x devices support EXT_CSD. */
@@ -1618,7 +1761,7 @@ mmc_discover_cards(struct mmc_softc *sc)
 			if (err != MMC_ERR_NONE) {
 				device_printf(sc->dev,
 				    "Error reading EXT_CSD %d\n", err);
-				break;
+				goto free_ivar;
 			}
 			/* Handle extended capacity from EXT_CSD */
 			sec_count = ivar->raw_ext_csd[EXT_CSD_SEC_CNT] +
@@ -1629,6 +1772,8 @@ mmc_discover_cards(struct mmc_softc *sc)
 				ivar->sec_count = sec_count;
 				ivar->high_cap = 1;
 			}
+			/* Find maximum supported bus width. */
+			ivar->bus_width = mmc_test_bus_width(sc);
 			/* Get device speeds beyond normal mode. */
 			if ((ivar->raw_ext_csd[EXT_CSD_CARD_TYPE] &
 			    EXT_CSD_CARD_TYPE_HS_52) != 0) {
@@ -1651,6 +1796,50 @@ mmc_discover_cards(struct mmc_softc *sc)
 				setbit(&ivar->timings, bus_timing_mmc_ddr52);
 				setbit(&ivar->vccq_180, bus_timing_mmc_ddr52);
 			}
+			if ((ivar->raw_ext_csd[EXT_CSD_CARD_TYPE] &
+			    EXT_CSD_CARD_TYPE_HS200_1_2V) != 0 &&
+			    (host_caps & MMC_CAP_SIGNALING_120) != 0) {
+				setbit(&ivar->timings, bus_timing_mmc_hs200);
+				setbit(&ivar->vccq_120, bus_timing_mmc_hs200);
+			}
+			if ((ivar->raw_ext_csd[EXT_CSD_CARD_TYPE] &
+			    EXT_CSD_CARD_TYPE_HS200_1_8V) != 0 &&
+			    (host_caps & MMC_CAP_SIGNALING_180) != 0) {
+				setbit(&ivar->timings, bus_timing_mmc_hs200);
+				setbit(&ivar->vccq_180, bus_timing_mmc_hs200);
+			}
+			if ((ivar->raw_ext_csd[EXT_CSD_CARD_TYPE] &
+			    EXT_CSD_CARD_TYPE_HS400_1_2V) != 0 &&
+			    (host_caps & MMC_CAP_SIGNALING_120) != 0 &&
+			    ivar->bus_width == bus_width_8) {
+				setbit(&ivar->timings, bus_timing_mmc_hs400);
+				setbit(&ivar->vccq_120, bus_timing_mmc_hs400);
+			}
+			if ((ivar->raw_ext_csd[EXT_CSD_CARD_TYPE] &
+			    EXT_CSD_CARD_TYPE_HS400_1_8V) != 0 &&
+			    (host_caps & MMC_CAP_SIGNALING_180) != 0 &&
+			    ivar->bus_width == bus_width_8) {
+				setbit(&ivar->timings, bus_timing_mmc_hs400);
+				setbit(&ivar->vccq_180, bus_timing_mmc_hs400);
+			}
+			if ((ivar->raw_ext_csd[EXT_CSD_CARD_TYPE] &
+			    EXT_CSD_CARD_TYPE_HS400_1_2V) != 0 &&
+			    (ivar->raw_ext_csd[EXT_CSD_STROBE_SUPPORT] &
+			    EXT_CSD_STROBE_SUPPORT_EN) != 0 &&
+			    (host_caps & MMC_CAP_SIGNALING_120) != 0 &&
+			    ivar->bus_width == bus_width_8) {
+				setbit(&ivar->timings, bus_timing_mmc_hs400es);
+				setbit(&ivar->vccq_120, bus_timing_mmc_hs400es);
+			}
+			if ((ivar->raw_ext_csd[EXT_CSD_CARD_TYPE] &
+			    EXT_CSD_CARD_TYPE_HS400_1_8V) != 0 &&
+			    (ivar->raw_ext_csd[EXT_CSD_STROBE_SUPPORT] &
+			    EXT_CSD_STROBE_SUPPORT_EN) != 0 &&
+			    (host_caps & MMC_CAP_SIGNALING_180) != 0 &&
+			    ivar->bus_width == bus_width_8) {
+				setbit(&ivar->timings, bus_timing_mmc_hs400es);
+				setbit(&ivar->vccq_180, bus_timing_mmc_hs400es);
+			}
 			/*
 			 * Determine generic switch timeout (provided in
 			 * units of 10 ms), defaulting to 500 ms.
@@ -1659,8 +1848,6 @@ mmc_discover_cards(struct mmc_softc *sc)
 			if (ivar->csd.spec_vers >= 6)
 				ivar->cmd6_time = 10 *
 				    ivar->raw_ext_csd[EXT_CSD_GEN_CMD6_TIME];
-			/* Find max supported bus width. */
-			ivar->bus_width = mmc_test_bus_width(sc);
 			/* Handle HC erase sector size. */
 			if (ivar->raw_ext_csd[EXT_CSD_ERASE_GRP_SIZE] != 0) {
 				ivar->erase_sector = 1024 *
@@ -1674,11 +1861,15 @@ mmc_discover_cards(struct mmc_softc *sc)
 					device_printf(sc->dev,
 					    "Error setting erase group %d\n",
 					    err);
-					break;
+					goto free_ivar;
 				}
 			}
 		}
 
+		mmc_decode_cid_mmc(ivar->raw_cid, &ivar->cid,
+		    ivar->raw_ext_csd[EXT_CSD_REV] >= 5);
+
+child_common:
 		/*
 		 * Some cards that report maximum I/O block sizes greater
 		 * than 512 require the block length to be set to 512, even
@@ -1691,8 +1882,6 @@ mmc_discover_cards(struct mmc_softc *sc)
 		    ivar->csd.write_bl_len != MMC_SECTOR_SIZE)
 			mmc_set_blocklen(sc, MMC_SECTOR_SIZE);
 
-		mmc_decode_cid_mmc(ivar->raw_cid, &ivar->cid,
-		    ivar->raw_ext_csd[EXT_CSD_REV] >= 5);
 		mmc_format_card_id_string(ivar);
 
 		if (bootverbose || mmc_debug)
@@ -1700,56 +1889,111 @@ mmc_discover_cards(struct mmc_softc *sc)
 		if (newcard) {
 			/* Add device. */
 			child = device_add_child(sc->dev, NULL, -1);
-			device_set_ivars(child, ivar);
+			if (child != NULL) {
+				device_set_ivars(child, ivar);
+				sc->child_list = realloc(sc->child_list,
+				    sizeof(device_t) * sc->child_count + 1,
+				    M_DEVBUF, M_WAITOK);
+				sc->child_list[sc->child_count++] = child;
+			} else
+				device_printf(sc->dev, "Error adding child\n");
 		}
-		mmc_select_card(sc, 0);
+
+free_ivar:
+		if (newcard && child == NULL)
+			free(ivar, M_DEVBUF);
+		(void)mmc_select_card(sc, 0);
+		/*
+		 * Not returning here when one MMC device could no be added
+		 * potentially would mean looping forever when that device
+		 * is broken (in which case it also may impact the remainder
+		 * of the bus anyway, though).
+		 */
+		if ((newcard && child == NULL) ||
+		    mmcbr_get_mode(sc->dev) == mode_sd)
+			return;
 	}
 }
 
 static void
+mmc_update_child_list(struct mmc_softc *sc)
+{
+	device_t child;
+	int i, j;
+
+	if (sc->child_count == 0) {
+		free(sc->child_list, M_DEVBUF);
+		return;
+	}
+	for (i = j = 0; i < sc->child_count; i++) {
+		for (;;) {
+			child = sc->child_list[j++];
+			if (child != NULL)
+				break;
+		}
+		if (i != j)
+			sc->child_list[i] = child;
+	}
+	sc->child_list = realloc(sc->child_list, sizeof(device_t) *
+	    sc->child_count, M_DEVBUF, M_WAITOK);
+}
+
+static void
 mmc_rescan_cards(struct mmc_softc *sc)
 {
 	struct mmc_ivars *ivar;
-	device_t *devlist;
-	int err, i, devcount;
+	int err, i, j;
 
-	if ((err = device_get_children(sc->dev, &devlist, &devcount)) != 0)
-		return;
-	for (i = 0; i < devcount; i++) {
-		ivar = device_get_ivars(devlist[i]);
+	for (i = j = 0; i < sc->child_count; i++) {
+		ivar = device_get_ivars(sc->child_list[i]);
 		if (mmc_select_card(sc, ivar->rca) != MMC_ERR_NONE) {
 			if (bootverbose || mmc_debug)
 				device_printf(sc->dev,
-				    "Card at relative address %d lost.\n",
+				    "Card at relative address %d lost\n",
 				    ivar->rca);
-			device_delete_child(sc->dev, devlist[i]);
+			err = device_delete_child(sc->dev, sc->child_list[i]);
+			if (err != 0) {
+				j++;
+				continue;
+			}
 			free(ivar, M_DEVBUF);
-		}
+		} else
+			j++;
 	}
-	free(devlist, M_TEMP);
-	mmc_select_card(sc, 0);
+	if (sc->child_count == j)
+		goto out;
+	sc->child_count = j;
+	mmc_update_child_list(sc);
+out:
+	(void)mmc_select_card(sc, 0);
 }
 
 static int
-mmc_delete_cards(struct mmc_softc *sc)
+mmc_delete_cards(struct mmc_softc *sc, bool final)
 {
 	struct mmc_ivars *ivar;
-	device_t *devlist;
-	int err, i, devcount;
+	int err, i, j;
 
-	if ((err = device_get_children(sc->dev, &devlist, &devcount)) != 0)
-		return (err);
-	for (i = 0; i < devcount; i++) {
-		ivar = device_get_ivars(devlist[i]);
+	err = 0;
+	for (i = j = 0; i < sc->child_count; i++) {
+		ivar = device_get_ivars(sc->child_list[i]);
 		if (bootverbose || mmc_debug)
 			device_printf(sc->dev,
-			    "Card at relative address %d deleted.\n",
+			    "Card at relative address %d deleted\n",
 			    ivar->rca);
-		device_delete_child(sc->dev, devlist[i]);
+		err = device_delete_child(sc->dev, sc->child_list[i]);
+		if (err != 0) {
+			j++;
+			if (final == false)
+				continue;
+			else
+				break;
+		}
 		free(ivar, M_DEVBUF);
 	}
-	free(devlist, M_TEMP);
-	return (0);
+	sc->child_count = j;
+	mmc_update_child_list(sc);
+	return (err);
 }
 
 static void
@@ -1813,7 +2057,7 @@ mmc_go_discovery(struct mmc_softc *sc)
 		    mmcbr_get_ocr(dev));
 	if (mmcbr_get_ocr(dev) == 0) {
 		device_printf(sc->dev, "No compatible cards found on bus\n");
-		mmc_delete_cards(sc);
+		(void)mmc_delete_cards(sc, false);
 		mmc_power_down(sc);
 		return;
 	}
@@ -1837,31 +2081,27 @@ mmc_go_discovery(struct mmc_softc *sc)
 static int
 mmc_calculate_clock(struct mmc_softc *sc)
 {
-	device_t *kids;
+	device_t dev;
 	struct mmc_ivars *ivar;
-	int host_caps, i, nkid;
+	int i;
 	uint32_t dtr, max_dtr;
+	uint16_t rca;
 	enum mmc_bus_timing max_timing, timing;
-	bool changed;
+	bool changed, hs400;
 
-	max_dtr = mmcbr_get_f_max(sc->dev);
-	host_caps = mmcbr_get_caps(sc->dev);
-	if ((host_caps & MMC_CAP_MMC_DDR52) != 0)
-		max_timing = bus_timing_mmc_ddr52;
-	else if ((host_caps & MMC_CAP_HSPEED) != 0)
-		max_timing = bus_timing_hs;
-	else
-		max_timing = bus_timing_normal;
-	if (device_get_children(sc->dev, &kids, &nkid) != 0)
-		panic("can't get children");
+	dev = sc->dev;
+	max_dtr = mmcbr_get_f_max(dev);
+	max_timing = bus_timing_max;
 	do {
 		changed = false;
-		for (i = 0; i < nkid; i++) {
-			ivar = device_get_ivars(kids[i]);
-			if (isclr(&ivar->timings, max_timing)) {
-				for (timing = max_timing; timing >=
+		for (i = 0; i < sc->child_count; i++) {
+			ivar = device_get_ivars(sc->child_list[i]);
+			if (isclr(&ivar->timings, max_timing) ||
+			    !mmc_host_timing(dev, max_timing)) {
+				for (timing = max_timing - 1; timing >=
 				    bus_timing_normal; timing--) {
-					if (isset(&ivar->timings, timing)) {
+					if (isset(&ivar->timings, timing) &&

*** DIFF OUTPUT TRUNCATED AT 1000 LINES ***


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