linux-kernel - [PATCH] PCI: qcom: Clear ASPM L0s CAP for MSM8996 SoC

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Message-ID: <20251126081718.8239-1-mani@kernel.org>
Date: Wed, 26 Nov 2025 13:47:18 +0530
From: Manivannan Sadhasivam <manivannan.sadhasivam@....qualcomm.com>
To: mani@...nel.org, lpieralisi@...nel.org, kwilczynski@...nel.org,
        bhelgaas@...gle.com
Cc: robh@...nel.org, linux-pci@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Manivannan Sadhasivam <manivannan.sadhasivam@....qualcomm.com>,
        Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
Subject: [PATCH] PCI: qcom: Clear ASPM L0s CAP for MSM8996 SoC

From: Manivannan Sadhasivam <manivannan.sadhasivam@....qualcomm.com>

Though I couldn't confirm the ASPM L0s support with the Qcom hardware team,
bug report from Dmitry suggests that L0s is broken on this legacy SoC.
Hence, clear the L0s CAP for the Root Ports in this SoC.

Since qcom_pcie_clear_aspm_l0s() is now used by more than one SoC config,
call it from qcom_pcie_host_init() instead.

Reported-by: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
Closes: https://lore.kernel.org/linux-pci/4cp5pzmlkkht2ni7us6p3edidnk25l45xrp6w3fxguqcvhq2id@wjqqrdpkypkf
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@....qualcomm.com>
---
 drivers/pci/controller/dwc/pcie-qcom.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
index 805edbbfe7eb..25399d47fc40 100644
--- a/drivers/pci/controller/dwc/pcie-qcom.c
+++ b/drivers/pci/controller/dwc/pcie-qcom.c
@@ -1088,7 +1088,6 @@ static int qcom_pcie_post_init_2_7_0(struct qcom_pcie *pcie)
 		writel(WR_NO_SNOOP_OVERRIDE_EN | RD_NO_SNOOP_OVERRIDE_EN,
 				pcie->parf + PARF_NO_SNOOP_OVERRIDE);
 
-	qcom_pcie_clear_aspm_l0s(pcie->pci);
 	qcom_pcie_clear_hpc(pcie->pci);
 
 	return 0;
@@ -1350,6 +1349,8 @@ static int qcom_pcie_host_init(struct dw_pcie_rp *pp)
 			goto err_disable_phy;
 	}
 
+	qcom_pcie_clear_aspm_l0s(pcie->pci);
+
 	qcom_ep_reset_deassert(pcie);
 
 	if (pcie->cfg->ops->config_sid) {
@@ -1486,6 +1487,7 @@ static const struct qcom_pcie_cfg cfg_2_1_0 = {
 
 static const struct qcom_pcie_cfg cfg_2_3_2 = {
 	.ops = &ops_2_3_2,
+	.no_l0s = true,
 };
 
 static const struct qcom_pcie_cfg cfg_2_3_3 = {
-- 
2.48.1