linux-kernel - [PATCH] phy: qcom-qmp: Correct READY

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Message-Id: <20190604232443.3417-1-bjorn.andersson@linaro.org>
Date:   Tue,  4 Jun 2019 16:24:43 -0700
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Kishon Vijay Abraham I <kishon@...com>
Cc:     linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org, Evan Green <evgreen@...omium.org>,
        Marc Gonzalez <marc.w.gonzalez@...e.fr>,
        Vivek Gautam <vivek.gautam@...eaurora.org>
Subject: [PATCH] phy: qcom-qmp: Correct READY_STATUS poll break condition

After issuing a PHY_START request to the QMP, the hardware documentation
states that the software should wait for the PCS_READY_STATUS to become
1.

With the introduction of c9b589791fc1 ("phy: qcom: Utilize UFS reset
controller") an additional 1ms delay was introduced between the start
request and the check of the status bit. This greatly increases the
chances for the hardware to actually becoming ready before the status
bit is read.

The result can be seen in that UFS PHY enabling is now reported as a
failure in 10% of the boots on SDM845, which is a clear regression from
the previous rare/occasional failure.

This patch fixes the "break condition" of the poll to check for the
correct state of the status bit.

Unfortunately PCIe on 8996 and 8998 does not specify the mask_pcs_ready
register, which means that the code checks a bit that's always 0. So the
patch also fixes these, in order to not regress these targets.

Cc: stable@...r.kernel.org
Cc: Evan Green <evgreen@...omium.org>
Cc: Marc Gonzalez <marc.w.gonzalez@...e.fr>
Cc: Vivek Gautam <vivek.gautam@...eaurora.org>
Fixes: 73d7ec899bd8 ("phy: qcom-qmp: Add msm8998 PCIe QMP PHY support")
Fixes: e78f3d15e115 ("phy: qcom-qmp: new qmp phy driver for qcom-chipsets")
Signed-off-by: Bjorn Andersson <bjorn.andersson@...aro.org>
---

@Kishon, this is a regression spotted in v5.2-rc1, so please consider applying
this towards v5.2.

 drivers/phy/qualcomm/phy-qcom-qmp.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/phy/qualcomm/phy-qcom-qmp.c b/drivers/phy/qualcomm/phy-qcom-qmp.c
index cd91b4179b10..43abdfd0deed 100644
--- a/drivers/phy/qualcomm/phy-qcom-qmp.c
+++ b/drivers/phy/qualcomm/phy-qcom-qmp.c
@@ -1074,6 +1074,7 @@ static const struct qmp_phy_cfg msm8996_pciephy_cfg = {

 	.start_ctrl		= PCS_START | PLL_READY_GATE_EN,
 	.pwrdn_ctrl		= SW_PWRDN | REFCLK_DRV_DSBL,
+	.mask_pcs_ready		= PHYSTATUS,
 	.mask_com_pcs_ready	= PCS_READY,

 	.has_phy_com_ctrl	= true,
@@ -1253,6 +1254,7 @@ static const struct qmp_phy_cfg msm8998_pciephy_cfg = {

 	.start_ctrl             = SERDES_START | PCS_START,
 	.pwrdn_ctrl		= SW_PWRDN | REFCLK_DRV_DSBL,
+	.mask_pcs_ready		= PHYSTATUS,
 	.mask_com_pcs_ready	= PCS_READY,
 };

@@ -1547,7 +1549,7 @@ static int qcom_qmp_phy_enable(struct phy *phy)
 	status = pcs + cfg->regs[QPHY_PCS_READY_STATUS];
 	mask = cfg->mask_pcs_ready;

-	ret = readl_poll_timeout(status, val, !(val & mask), 1,
+	ret = readl_poll_timeout(status, val, val & mask, 1,
 				 PHY_INIT_COMPLETE_TIMEOUT);
 	if (ret) {
 		dev_err(qmp->dev, "phy initialization timed-out\n");
-- 
2.18.0