linux-kernel - [PATCH v4 04/10] scsi: ufs: ufs-qcom: Limit negotiated gear to selected PHY gear

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Message-Id: <1700728577-14729-5-git-send-email-quic_cang@quicinc.com>
Date:   Thu, 23 Nov 2023 00:36:10 -0800
From:   Can Guo <quic_cang@...cinc.com>
To:     quic_cang@...cinc.com, bvanassche@....org, mani@...nel.org,
        adrian.hunter@...el.com, beanhuo@...ron.com, avri.altman@....com,
        junwoo80.lee@...sung.com, martin.petersen@...cle.com
Cc:     linux-scsi@...r.kernel.org, Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        linux-arm-msm@...r.kernel.org (open list:ARM/QUALCOMM SUPPORT),
        linux-kernel@...r.kernel.org (open list)
Subject: [PATCH v4 04/10] scsi: ufs: ufs-qcom: Limit negotiated gear to selected PHY gear

In the dual init scenario, the initial PHY gear is set to HS-G2, and the
first Power Mode Change (PMC) is meant to find the best matching PHY gear
for the 2nd init. However, for the first PMC, if the negotiated gear (say
HS-G4) is higher than the initial PHY gear, we cannot go ahead let PMC to
the negotiated gear happen, because the programmed UFS PHY settings may not
support the negotiated gear. Fix it by overwriting the negotiated gear with
the PHY gear.

Signed-off-by: Can Guo <quic_cang@...cinc.com>
---
 drivers/ufs/host/ufs-qcom.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/ufs/host/ufs-qcom.c b/drivers/ufs/host/ufs-qcom.c
index cc0eb37..d4edf58 100644
--- a/drivers/ufs/host/ufs-qcom.c
+++ b/drivers/ufs/host/ufs-qcom.c
@@ -920,8 +920,13 @@ static int ufs_qcom_pwr_change_notify(struct ufs_hba *hba,
 		 * because, the PHY gear settings are backwards compatible and we only need to
 		 * change the PHY gear settings while scaling to higher gears.
 		 */
-		if (dev_req_params->gear_tx > host->phy_gear)
+		if (dev_req_params->gear_tx > host->phy_gear) {
+			u32 old_phy_gear = host->phy_gear;
+
 			host->phy_gear = dev_req_params->gear_tx;
+			dev_req_params->gear_tx = old_phy_gear;
+			dev_req_params->gear_rx = old_phy_gear;
+		}
 
 		/* enable the device ref clock before changing to HS mode */
 		if (!ufshcd_is_hs_mode(&hba->pwr_info) &&
-- 
2.7.4