linux-kernel - [PATCH v2 1/2] phy: qcom-qmp-pcie: Fix high latency with 4x2 PHY when ASPM is enabled

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Date:   Wed,  2 Nov 2022 13:48:34 +0530
From:   Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To:     vkoul@...nel.org
Cc:     andersson@...nel.org, dmitry.baryshkov@...aro.org,
        linux-arm-msm@...r.kernel.org, linux-phy@...ts.infradead.org,
        linux-kernel@...r.kernel.org,
        Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Subject: [PATCH v2 1/2] phy: qcom-qmp-pcie: Fix high latency with 4x2 PHY when ASPM is enabled

The PCIe QMP 4x2 RC PHY generates high latency when ASPM is enabled. This
seem to be fixed by clearing the QPHY_V5_20_PCS_PCIE_PRESET_P10_POST
register of the pcs_misc register space.

Fixes: 2c91bf6bf290 ("phy: qcom-qmp: Add SM8450 PCIe1 PHY support")
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
---

Changes in v2

* Dropped the changes to PCS_PCIE_EQ_CONFIG{2/3} registers and added
a new PCS_PCIE_PRESET_P10_POST register

 drivers/phy/qualcomm/phy-qcom-qmp-pcie.c           | 1 +
 drivers/phy/qualcomm/phy-qcom-qmp-pcs-pcie-v5_20.h | 1 +
 2 files changed, 2 insertions(+)

diff --git a/drivers/phy/qualcomm/phy-qcom-qmp-pcie.c b/drivers/phy/qualcomm/phy-qcom-qmp-pcie.c
index f3f75eda01a6..9473f63d2c1c 100644
--- a/drivers/phy/qualcomm/phy-qcom-qmp-pcie.c
+++ b/drivers/phy/qualcomm/phy-qcom-qmp-pcie.c
@@ -1305,6 +1305,7 @@ static const struct qmp_phy_init_tbl sm8450_qmp_gen4x2_pcie_pcs_misc_tbl[] = {
 static const struct qmp_phy_init_tbl sm8450_qmp_gen4x2_pcie_rc_pcs_misc_tbl[] = {
 	QMP_PHY_INIT_CFG(QPHY_V5_20_PCS_PCIE_ENDPOINT_REFCLK_DRIVE, 0xc1),
 	QMP_PHY_INIT_CFG(QPHY_V5_20_PCS_PCIE_OSC_DTCT_ACTIONS, 0x00),
+	QMP_PHY_INIT_CFG(QPHY_V5_20_PCS_PCIE_PRESET_P10_POST, 0x00),
 };
 
 static const struct qmp_phy_init_tbl sm8450_qmp_gen4x2_pcie_ep_serdes_tbl[] = {
diff --git a/drivers/phy/qualcomm/phy-qcom-qmp-pcs-pcie-v5_20.h b/drivers/phy/qualcomm/phy-qcom-qmp-pcs-pcie-v5_20.h
index c9fa90b45475..3d9713d348fe 100644
--- a/drivers/phy/qualcomm/phy-qcom-qmp-pcs-pcie-v5_20.h
+++ b/drivers/phy/qualcomm/phy-qcom-qmp-pcs-pcie-v5_20.h
@@ -11,6 +11,7 @@
 #define QPHY_V5_20_PCS_PCIE_OSC_DTCT_MODE2_CONFIG5	0x084
 #define QPHY_V5_20_PCS_PCIE_OSC_DTCT_ACTIONS		0x090
 #define QPHY_V5_20_PCS_PCIE_EQ_CONFIG1			0x0a0
+#define QPHY_V5_20_PCS_PCIE_PRESET_P10_POST		0x0e0
 #define QPHY_V5_20_PCS_PCIE_G4_EQ_CONFIG5		0x108
 #define QPHY_V5_20_PCS_PCIE_G4_PRE_GAIN			0x15c
 #define QPHY_V5_20_PCS_PCIE_RX_MARGINING_CONFIG3	0x184
-- 
2.25.1