svn commit: r289271 - head/sys/dev/ntb/ntb_hw

[Conrad E. Meyer]

Author: cem
Date: Tue Oct 13 23:41:06 2015
New Revision: 289271
URL: https://svnweb.freebsd.org/changeset/base/289271

Log:
  NTB: MFV c529aa30: Xeon Doorbell errata workaround
  
  Modifications to the 14th bit of the B2BDOORBELL register will not be
  mirrored to the remote system due to a hardware issue.  To get around
  the issue, shrink the number of available doorbell bits by 1.  The max
  number of doorbells was being used as a way to referencing the Link
  Doorbell bit.  Since this would no longer work, the driver must now
  explicitly reference that bit.
  
  This does not affect the xeon_errata_workaround case, as it is not using
  the b2bdoorbell register.
  
  Authored by:	Jon Mason
  Obtained from:	Linux (Dual BSD/GPL driver)
  Sponsored by:	EMC / Isilon Storage Division

Modified:
  head/sys/dev/ntb/ntb_hw/ntb_hw.c
  head/sys/dev/ntb/ntb_hw/ntb_regs.h

Modified: head/sys/dev/ntb/ntb_hw/ntb_hw.c
==============================================================================
--- head/sys/dev/ntb/ntb_hw/ntb_hw.c	Tue Oct 13 23:30:54 2015	(r289270)
+++ head/sys/dev/ntb/ntb_hw/ntb_hw.c	Tue Oct 13 23:41:06 2015	(r289271)
@@ -479,7 +479,7 @@ ntb_setup_interrupts(struct ntb_softc *n
 		ntb_reg_write(8, ntb->reg_ofs.ldb_mask, ~0);
 	else
 		ntb_reg_write(2, ntb->reg_ofs.ldb_mask,
-		    ~(1 << ntb->limits.max_db_bits));
+		    (uint16_t) ~(1 << XEON_LINK_DB));
 
 	num_vectors = MIN(pci_msix_count(ntb->device),
 	    ntb->limits.max_db_bits);
@@ -616,7 +616,7 @@ handle_xeon_event_irq(void *arg)
 		device_printf(ntb->device, "Error determining link status\n");
 
 	/* bit 15 is always the link bit */
-	ntb_reg_write(2, ntb->reg_ofs.ldb, 1 << ntb->limits.max_db_bits);
+	ntb_reg_write(2, ntb->reg_ofs.ldb, 1 << XEON_LINK_DB);
 }
 
 static void
@@ -784,6 +784,19 @@ ntb_setup_xeon(struct ntb_softc *ntb)
 	ntb->limits.msix_cnt	 = XEON_MSIX_CNT;
 	ntb->bits_per_vector	 = XEON_DB_BITS_PER_VEC;
 
+	/*
+	 * HW Errata on bit 14 of b2bdoorbell register.  Writes will not be
+	 * mirrored to the remote system.  Shrink the number of bits by one,
+	 * since bit 14 is the last bit.
+	 *
+	 * On REGS_THRU_MW errata mode, we don't use the b2bdoorbell register
+	 * anyway.  Nor for non-B2B connection types.
+	 */
+	if (HAS_FEATURE(NTB_B2BDOORBELL_BIT14) &&
+	    !HAS_FEATURE(NTB_REGS_THRU_MW) &&
+	    connection_type == NTB_CONN_B2B)
+		ntb->limits.max_db_bits = XEON_MAX_DB_BITS - 1;
+
 	configure_xeon_secondary_side_bars(ntb);
 
 	/* Enable Bus Master and Memory Space on the secondary side */

Modified: head/sys/dev/ntb/ntb_hw/ntb_regs.h
==============================================================================
--- head/sys/dev/ntb/ntb_hw/ntb_regs.h	Tue Oct 13 23:30:54 2015	(r289270)
+++ head/sys/dev/ntb/ntb_hw/ntb_regs.h	Tue Oct 13 23:41:06 2015	(r289271)
@@ -38,6 +38,7 @@
 #define XEON_MAX_COMPAT_SPADS	16
 /* Reserve the uppermost bit for link interrupt */
 #define XEON_MAX_DB_BITS	15
+#define XEON_LINK_DB		15
 #define XEON_DB_BITS_PER_VEC	5
 
 #define XEON_DB_HW_LINK		0x8000