Commit c2e0da84 authored by Jim Harris's avatar Jim Harris
Browse files

nvme: improve comment for nvme_pcie_ctrlr_get_max_xfer_size 



NVME_MAX_PRP_LIST_ENTRIES has changed over time, so let's
just remove the reference to the exact value here.  Also
explain a bit more why the max size isn't
(NUM_ENTRIES + 1) * page_size.

While here, do a small whitespace cleanup as well.

Signed-off-by: default avatarJim Harris <james.r.harris@intel.com>
Change-Id: Ib75813788abdd3dbb43192f9fdc27f99b33aeadf
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/7328


Tested-by: default avatarSPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: default avatarChangpeng Liu <changpeng.liu@intel.com>
Reviewed-by: default avatarShuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com>
Reviewed-by: default avatarAleksey Marchuk <alexeymar@mellanox.com>
parent 17fdcd71

lib/nvme/nvme_pcie.c

+8 −4
Original line number Diff line number Diff line
@@ -277,9 +277,13 @@ nvme_pcie_ctrlr_get_max_xfer_size(struct spdk_nvme_ctrlr *ctrlr) 
	/*

	 * For commands requiring more than 2 PRP entries, one PRP will be

	 *  embedded in the command (prp1), and the rest of the PRP entries

	 *  will be in a list pointed to by the command (prp2).  This means

	 *  that real max number of PRP entries we support is 506+1, which

	 *  results in a max xfer size of 506*ctrlr->page_size.

	 *  will be in a list pointed to by the command (prp2).  The number

	 *  of PRP entries in the list is defined by

	 *  NVME_MAX_PRP_LIST_ENTRIES.

	 *

	 *  Note that the max xfer size is not (MAX_ENTRIES + 1) * page_size

	 *  because the first PRP entry may not be aligned on a 4KiB

	 *  boundary.

	 */

	return NVME_MAX_PRP_LIST_ENTRIES * ctrlr->page_size;

}