linux-kernel - [PATCH] phy: ufs-qcom: Invert PCS ready logic for SDM845 UFS

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Message-Id: <20191209135934.1.Iaaf3ad8a27b00f2f2bc333486a1ecc9985bb5170@changeid>
Date:   Mon,  9 Dec 2019 14:00:12 -0800
From:   Evan Green <evgreen@...omium.org>
To:     Kishon Vijay Abraham I <kishon@...com>,
        Bjorn Andersson <bjorn.andersson@...aro.org>
Cc:     Can Guo <cang@...eaurora.org>,
        Douglas Anderson <dianders@...omium.org>,
        Evan Green <evgreen@...omium.org>,
        linux-kernel@...r.kernel.org, Andy Gross <agross@...nel.org>,
        linux-arm-msm@...r.kernel.org
Subject: [PATCH] phy: ufs-qcom: Invert PCS ready logic for SDM845 UFS

The SDM845 UFS phy seems to want to do a low transition to become
ready, rather than a high transition. Without this, I am unable to
enumerate UFS on SDM845 when booted from USB.

Fixes: 14ced7e3a1a ('phy: qcom-qmp: Correct ready status, again')

Signed-off-by: Evan Green <evgreen@...omium.org>
---

Bjorn,
At this point I'm super confused on what the correct behavior
should be. Lack of documentation doesn't help. I'm worried that this
change breaks UFS on some other platforms, so I'm hoping you or some
PHY folks might have some advice on what the right thing to do is.

---
 drivers/phy/qualcomm/phy-qcom-qmp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/phy/qualcomm/phy-qcom-qmp.c b/drivers/phy/qualcomm/phy-qcom-qmp.c
index 091e20303a14d..c4f4294360b6e 100644
--- a/drivers/phy/qualcomm/phy-qcom-qmp.c
+++ b/drivers/phy/qualcomm/phy-qcom-qmp.c
@@ -1657,7 +1657,7 @@ static int qcom_qmp_phy_enable(struct phy *phy)
 	if (cfg->type == PHY_TYPE_UFS) {
 		status = pcs + cfg->regs[QPHY_PCS_READY_STATUS];
 		mask = PCS_READY;
-		ready = PCS_READY;
+		ready = 0;
 	} else {
 		status = pcs + cfg->regs[QPHY_PCS_STATUS];
 		mask = PHYSTATUS;
-- 
2.21.0