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From:   Can Guo <cang@qti.qualcomm.com>
To:     asutoshd@codeaurora.org, nguyenb@codeaurora.org,
        rnayak@codeaurora.org, linux-scsi@vger.kernel.org,
        kernel-team@android.com, saravanak@google.com, salyzyn@google.com,
        cang@codeaurora.org
Cc:     "James E.J. Bottomley" <jejb@linux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@oracle.com>,
        linux-kernel@vger.kernel.org (open list)
Subject: [PATCH v3 1/5] scsi: Adjust DBD setting in mode sense for caching mode page per LLD
Date:   Fri,  1 Nov 2019 18:20:26 -0700
Message-Id: <1572657631-25749-2-git-send-email-cang@qti.qualcomm.com>
In-Reply-To: <1572657631-25749-1-git-send-email-cang@qti.qualcomm.com>
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From: Can Guo <cang@codeaurora.org>

Host sends MODE_SENSE_10 with caching mode page, to check if the device
supports the cache feature.
UFS JEDEC standards require DBD field to be set to 1.

This patch allows LLD to define the setting of DBD if required.

Signed-off-by: Can Guo <cang@codeaurora.org>
---
 drivers/scsi/sd.c        | 2 +-
 include/scsi/scsi_host.h | 6 ++++++
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index aab4ed8..a9cca2f 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -2660,7 +2660,7 @@ static int sd_try_rc16_first(struct scsi_device *sdp)
 		dbd = 8;
 	} else {
 		modepage = 8;
-		dbd = 0;
+		dbd = sdp->host->set_dbd_for_caching ? 8 : 0;
 	}
 
 	/* cautiously ask */
diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index 2c3f0c5..3900987 100644
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -650,6 +650,12 @@ struct Scsi_Host {
 	unsigned no_scsi2_lun_in_cdb:1;
 
 	/*
+	 * Set "DBD" field in mode_sense caching mode page in case it is
+	 * mandatory by LLD standard.
+	 */
+	unsigned set_dbd_for_caching:1;
+
+	/*
 	 * Optional work queue to be utilized by the transport
 	 */
 	char work_q_name[20];
-- 
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