svn commit: r248762 - head/sys/dev/nvme

[Jim Harris]

Author: jimharris
Date: Tue Mar 26 21:16:53 2013
New Revision: 248762
URL: http://svnweb.freebsd.org/changeset/base/248762

Log:
  Ensure the controller's MDTS is accounted for in max_xfer_size.
  
  The controller's IDENTIFY data contains MDTS (Max Data Transfer Size) to
  allow the controller to specify the maximum I/O data transfer size.  nvme(4)
  already provides a default maximum, but make sure it does not exceed what
  MDTS reports.
  
  Sponsored by:	Intel
  Reviewed by:	carl

Modified:
  head/sys/dev/nvme/nvme_ctrlr.c
  head/sys/dev/nvme/nvme_private.h

Modified: head/sys/dev/nvme/nvme_ctrlr.c
==============================================================================
--- head/sys/dev/nvme/nvme_ctrlr.c	Tue Mar 26 21:14:51 2013	(r248761)
+++ head/sys/dev/nvme/nvme_ctrlr.c	Tue Mar 26 21:16:53 2013	(r248762)
@@ -457,6 +457,14 @@ nvme_ctrlr_identify(struct nvme_controll
 		nvme_chatham_populate_cdata(ctrlr);
 #endif
 
+	/*
+	 * Use MDTS to ensure our default max_xfer_size doesn't exceed what the
+	 *  controller supports.
+	 */
+	if (ctrlr->cdata.mdts > 0)
+		ctrlr->max_xfer_size = min(ctrlr->max_xfer_size,
+		    ctrlr->min_page_size * (1 << (ctrlr->cdata.mdts)));
+
 	return (0);
 }
 
@@ -923,6 +931,8 @@ nvme_ctrlr_construct(struct nvme_control
 	if (cap_hi.bits.dstrd != 0)
 		return (ENXIO);
 
+	ctrlr->min_page_size = 1 << (12 + cap_hi.bits.mpsmin);
+
 	/* Get ready timeout value from controller, in units of 500ms. */
 	cap_lo.raw = nvme_mmio_read_4(ctrlr, cap_lo);
 	ctrlr->ready_timeout_in_ms = cap_lo.bits.to * 500;

Modified: head/sys/dev/nvme/nvme_private.h
==============================================================================
--- head/sys/dev/nvme/nvme_private.h	Tue Mar 26 21:14:51 2013	(r248761)
+++ head/sys/dev/nvme/nvme_private.h	Tue Mar 26 21:16:53 2013	(r248762)
@@ -265,6 +265,9 @@ struct nvme_controller {
 	/** maximum i/o size in bytes */
 	uint32_t		max_xfer_size;
 
+	/** minimum page size supported by this controller in bytes */
+	uint32_t		min_page_size;
+
 	/** interrupt coalescing time period (in microseconds) */
 	uint32_t		int_coal_time;