Re: [PATCH v2 01/10] scsi: ufs: Allowing power mode change

From: Subhash Jadavani
Date: Wed May 16 2018 - 16:37:22 EST


On 2018-05-03 04:07, Asutosh Das wrote:
From: Yaniv Gardi <ygardi@xxxxxxxxxxxxxx>

Due to M-PHY issues, moving from HS to any other mode or gear or
even Hibern8 may cause some un-predicted behavior
of the device.
This patch adds provides a quirk to address that.

Signed-off-by: Yaniv Gardi <ygardi@xxxxxxxxxxxxxx>
Signed-off-by: Subhash Jadavani <subhashj@xxxxxxxxxxxxxx>
Signed-off-by: Can Guo <cang@xxxxxxxxxxxxxx>
Signed-off-by: Asutosh Das <asutoshd@xxxxxxxxxxxxxx>
---
drivers/scsi/ufs/ufshcd.c | 8 +++++++-
drivers/scsi/ufs/ufshcd.h | 7 +++++++
2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 5bc9dc1..f3083fe 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -4162,9 +4162,15 @@ static int ufshcd_link_startup(struct ufs_hba *hba)
goto out;
} while (ret && retries--);

- if (ret)
+ if (ret) {
/* failed to get the link up... retire */
goto out;
+ }
+
+ if (hba->quirks & UFSHCD_QUIRK_BROKEN_PWR_MODE_CHANGE) {
+ ufshcd_dme_set(hba, UIC_ARG_MIB(TX_LCC_ENABLE), 0);
+ ufshcd_dme_set(hba, UIC_ARG_MIB(TX_LCC_ENABLE), 1);
+ }

if (link_startup_again) {
link_startup_again = false;
diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h
index cbe46f6..bb4ecfb 100644
--- a/drivers/scsi/ufs/ufshcd.h
+++ b/drivers/scsi/ufs/ufshcd.h
@@ -591,6 +591,13 @@ struct ufs_hba {
*/
#define UFSHCD_QUIRK_PRDT_BYTE_GRAN UFS_BIT(7)

+ /*
+ * Needs to be enabled if moving from HS to any other gear/mode or even
+ * hibern8 causes unpredicted behavior of device.
+ * If this quirk is enabled, standard UFS driver will disable/enable
+ * TX_LCC.
+ */
+ #define UFSHCD_QUIRK_BROKEN_PWR_MODE_CHANGE UFS_BIT(8)
unsigned int quirks; /* Deviations from standard UFSHCI spec. */

/* Device deviations from standard UFS device spec. */

This was probably needed in early generation of UFS devices (non commercial) and may not be really needed now. I believe we can skip this patch.

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