git: 9c9d7fdd9f00 - main - ig4: Fix FIFO depths detection

The branch main has been updated by mav:

URL: https://cgit.FreeBSD.org/src/commit/?id=9c9d7fdd9f0041783955c5f540ac55a900877c0c

commit 9c9d7fdd9f0041783955c5f540ac55a900877c0c
Author:     Alexander Motin <mav@FreeBSD.org>
AuthorDate: 2023-12-24 00:02:49 +0000
Commit:     Alexander Motin <mav@FreeBSD.org>
CommitDate: 2023-12-24 00:02:49 +0000

    ig4: Fix FIFO depths detection
    
    At least on my Tiger Lake-LP queue depth detection failed before the
    ig4iic_set_config() call, resulting in no FIFO use.  Moving it after
    solves the problem, getting proper 64 bytes size.
    
    On my Dell XPS 13 9310 with iichid(4) touchscreen and touchpad this
    by few times reduces context switch rate in the driver, and probably
    also improves the I2C bus utilization.
    
    MFC after:      1 month
---
 sys/dev/ichiic/ig4_iic.c | 50 ++++++++++++++++++++++++++++++------------------
 1 file changed, 31 insertions(+), 19 deletions(-)

diff --git a/sys/dev/ichiic/ig4_iic.c b/sys/dev/ichiic/ig4_iic.c
index 3dc72c458b24..4ab36ef660ed 100644
--- a/sys/dev/ichiic/ig4_iic.c
+++ b/sys/dev/ichiic/ig4_iic.c
@@ -850,23 +850,6 @@ ig4iic_get_config(ig4iic_softc_t *sc)
 			sc->cfg.txfifo_depth = IG4_PARAM1_TXFIFO_DEPTH(v);
 		if (IG4_PARAM1_RXFIFO_DEPTH(v) != 0)
 			sc->cfg.rxfifo_depth = IG4_PARAM1_RXFIFO_DEPTH(v);
-	} else {
-		/*
-		 * Hardware does not allow FIFO Threshold Levels value to be
-		 * set larger than the depth of the buffer. If an attempt is
-		 * made to do that, the actual value set will be the maximum
-		 * depth of the buffer.
-		 */
-		v = reg_read(sc, IG4_REG_TX_TL);
-		reg_write(sc, IG4_REG_TX_TL, v | IG4_FIFO_MASK);
-		sc->cfg.txfifo_depth =
-		    (reg_read(sc, IG4_REG_TX_TL) & IG4_FIFO_MASK) + 1;
-		reg_write(sc, IG4_REG_TX_TL, v);
-		v = reg_read(sc, IG4_REG_RX_TL);
-		reg_write(sc, IG4_REG_RX_TL, v | IG4_FIFO_MASK);
-		sc->cfg.rxfifo_depth =
-		    (reg_read(sc, IG4_REG_RX_TL) & IG4_FIFO_MASK) + 1;
-		reg_write(sc, IG4_REG_RX_TL, v);
 	}
 
 	/* Override hardware config with IC_clock-based counter values */
@@ -918,8 +901,6 @@ ig4iic_get_config(ig4iic_softc_t *sc)
 		printf("  Fast:  0x%04hx:0x%04hx:0x%04hx\n",
 		    sc->cfg.fs_scl_hcnt, sc->cfg.fs_scl_lcnt,
 		    sc->cfg.fs_sda_hold);
-		printf("  FIFO:  RX:0x%04x: TX:0x%04x\n",
-		    sc->cfg.rxfifo_depth, sc->cfg.txfifo_depth);
 	}
 }
 
@@ -1015,6 +996,36 @@ ig4iic_set_config(ig4iic_softc_t *sc, bool reset)
 	return (0);
 }
 
+static void
+ig4iic_get_fifo(ig4iic_softc_t *sc)
+{
+	uint32_t v;
+
+	/*
+	 * Hardware does not allow FIFO Threshold Levels value to be set larger
+	 * than the depth of the buffer.  If an attempt is made to do that, the
+	 * actual value set will be the maximum depth of the buffer.
+	 */
+	if (sc->cfg.txfifo_depth == 0) {
+		v = reg_read(sc, IG4_REG_TX_TL);
+		reg_write(sc, IG4_REG_TX_TL, v | IG4_FIFO_MASK);
+		sc->cfg.txfifo_depth =
+		    (reg_read(sc, IG4_REG_TX_TL) & IG4_FIFO_MASK) + 1;
+		reg_write(sc, IG4_REG_TX_TL, v);
+	}
+	if (sc->cfg.rxfifo_depth == 0) {
+		v = reg_read(sc, IG4_REG_RX_TL);
+		reg_write(sc, IG4_REG_RX_TL, v | IG4_FIFO_MASK);
+		sc->cfg.rxfifo_depth =
+		    (reg_read(sc, IG4_REG_RX_TL) & IG4_FIFO_MASK) + 1;
+		reg_write(sc, IG4_REG_RX_TL, v);
+	}
+	if (bootverbose) {
+		printf("  FIFO:  RX:0x%04x: TX:0x%04x\n",
+		    sc->cfg.rxfifo_depth, sc->cfg.txfifo_depth);
+	}
+}
+
 /*
  * Called from ig4iic_pci_attach/detach()
  */
@@ -1031,6 +1042,7 @@ ig4iic_attach(ig4iic_softc_t *sc)
 	error = ig4iic_set_config(sc, IG4_HAS_ADDREGS(sc->version));
 	if (error)
 		goto done;
+	ig4iic_get_fifo(sc);
 
 	sc->iicbus = device_add_child(sc->dev, "iicbus", -1);
 	if (sc->iicbus == NULL) {