Commit 1ea7d802 authored by Bart Van Assche's avatar Bart Van Assche Committed by Martin K. Petersen
Browse files

scsi: ufs: core: Micro-optimize ufshcd_map_sg() 

Replace two cpu_to_le32() calls by a single cpu_to_le64() call.

Additionally, issue a warning if the length of an scatter gather list
element exceeds what is allowed by the UFSHCI specification.

Link: https://lore.kernel.org/r/20211020214024.2007615-11-bvanassche@acm.org


Acked-by: default avatarAvri Altman <Avri.Altman@wdc.com>
Signed-off-by: default avatarBart Van Assche <bvanassche@acm.org>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
parent 9a868c8a

drivers/scsi/ufs/ufshcd.c

+13 −6
Original line number Diff line number Diff line
@@ -2379,12 +2379,19 @@ static int ufshcd_map_sg(struct ufs_hba *hba, struct ufshcd_lrb *lrbp) 
		prd_table = lrbp->ucd_prdt_ptr;



		scsi_for_each_sg(cmd, sg, sg_segments, i) {

			prd_table[i].size  =

				cpu_to_le32(((u32) sg_dma_len(sg))-1);

			prd_table[i].base_addr =

				cpu_to_le32(lower_32_bits(sg->dma_address));

			prd_table[i].upper_addr =

				cpu_to_le32(upper_32_bits(sg->dma_address));

			const unsigned int len = sg_dma_len(sg);



			/*

			 * From the UFSHCI spec: "Data Byte Count (DBC): A '0'

			 * based value that indicates the length, in bytes, of

			 * the data block. A maximum of length of 256KB may

			 * exist for any entry. Bits 1:0 of this field shall be

			 * 11b to indicate Dword granularity. A value of '3'

			 * indicates 4 bytes, '7' indicates 8 bytes, etc."

			 */

			WARN_ONCE(len > 256 * 1024, "len = %#x\n", len);

			prd_table[i].size = cpu_to_le32(len - 1);

			prd_table[i].addr = cpu_to_le64(sg->dma_address);

			prd_table[i].reserved = 0;

		}

	} else {

drivers/scsi/ufs/ufshci.h

+2 −4
Original line number Diff line number Diff line
@@ -415,14 +415,12 @@ enum { 


/**

 * struct ufshcd_sg_entry - UFSHCI PRD Entry

 * @base_addr: Lower 32bit physical address DW-0

 * @upper_addr: Upper 32bit physical address DW-1

 * @addr: Physical address; DW-0 and DW-1.

 * @reserved: Reserved for future use DW-2

 * @size: size of physical segment DW-3

 */

struct ufshcd_sg_entry {

	__le32    base_addr;

	__le32    upper_addr;

	__le64    addr;

	__le32    reserved;

	__le32    size;

};