Commit 00d2fa28 authored by Bart Van Assche's avatar Bart Van Assche Committed by Martin K. Petersen
Browse files

scsi: ufs: core: Set the Command Priority (CP) flag for RT requests 



Make the UFS device execute realtime (RT) requests before other requests.
This will be used in Android to reduce the I/O latency of the foreground
app.

Note: UFS devices do not support CDL so using CDL is not a viable
alternative.

Signed-off-by: default avatarBart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20230921192335.676924-5-bvanassche@acm.org


Reviewed-by: default avatarAvri Altman <avri.altman@wdc.com>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
parent c788cf8a

drivers/ufs/core/ufshcd.c

+4 −0
Original line number Diff line number Diff line
@@ -2717,6 +2717,8 @@ static int ufshcd_compose_devman_upiu(struct ufs_hba *hba, 
 */

static void ufshcd_comp_scsi_upiu(struct ufs_hba *hba, struct ufshcd_lrb *lrbp)

{

	struct request *rq = scsi_cmd_to_rq(lrbp->cmd);

	unsigned int ioprio_class = IOPRIO_PRIO_CLASS(req_get_ioprio(rq));

	u8 upiu_flags;



	if (hba->ufs_version <= ufshci_version(1, 1))
@@ -2726,6 +2728,8 @@ static void ufshcd_comp_scsi_upiu(struct ufs_hba *hba, struct ufshcd_lrb *lrbp) 


	ufshcd_prepare_req_desc_hdr(lrbp, &upiu_flags,

				    lrbp->cmd->sc_data_direction, 0);

	if (ioprio_class == IOPRIO_CLASS_RT)

		upiu_flags |= UPIU_CMD_FLAGS_CP;

	ufshcd_prepare_utp_scsi_cmd_upiu(lrbp, upiu_flags);

}

include/ufs/ufs.h

+2 −1
Original line number Diff line number Diff line
@@ -98,9 +98,10 @@ enum upiu_response_transaction { 
	UPIU_TRANSACTION_REJECT_UPIU	= 0x3F,

};



/* UPIU Read/Write flags */

/* UPIU Read/Write flags. See also table "UPIU Flags" in the UFS standard. */

enum {

	UPIU_CMD_FLAGS_NONE	= 0x00,

	UPIU_CMD_FLAGS_CP	= 0x04,

	UPIU_CMD_FLAGS_WRITE	= 0x20,

	UPIU_CMD_FLAGS_READ	= 0x40,

};