linux-kernel - [PATCH v2] PCI: qcom-ep: Enable controller resources like PHY only after refclk is available

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Message-Id: <20240828140108.5562-1-manivannan.sadhasivam@linaro.org>
Date: Wed, 28 Aug 2024 19:31:08 +0530
From: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To: lpieralisi@...nel.org,
	kw@...ux.com,
	bhelgaas@...gle.com
Cc: robh@...nel.org,
	linux-pci@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-arm-msm@...r.kernel.org,
	Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
	Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Subject: [PATCH v2] PCI: qcom-ep: Enable controller resources like PHY only after refclk is available

qcom_pcie_enable_resources() is called by qcom_pcie_ep_probe() and it
enables the controller resources like clocks, regulator, PHY. On one of the
new unreleased Qcom SoC, PHY enablement depends on the active refclk. And
on all of the supported Qcom endpoint SoCs, refclk comes from the host
(RC). So calling qcom_pcie_enable_resources() without refclk causes the
whole SoC crash on the new SoC.

qcom_pcie_enable_resources() is already called by
qcom_pcie_perst_deassert() when PERST# is deasserted, and refclk is
available at that time.

Hence, remove the unnecessary call to qcom_pcie_enable_resources() from
qcom_pcie_ep_probe() to prevent the crash.

Fixes: 869bc5253406 ("PCI: dwc: ep: Fix DBI access failure for drivers requiring refclk from host")
Tested-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
---

Changes in v2:

- Changed the patch description to mention the crash clearly as suggested by
  Bjorn
- Added the Fixes tag

Bjorn: This is not going to be a 6.11 material as it is not fixing a regression
introduced in 6.11 (offending commit got merged in 6.10). So please merge this
patch for 6.12.

 drivers/pci/controller/dwc/pcie-qcom-ep.c | 14 ++++----------
 1 file changed, 4 insertions(+), 10 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-qcom-ep.c b/drivers/pci/controller/dwc/pcie-qcom-ep.c
index 236229f66c80..2319ff2ae9f6 100644
--- a/drivers/pci/controller/dwc/pcie-qcom-ep.c
+++ b/drivers/pci/controller/dwc/pcie-qcom-ep.c
@@ -846,21 +846,15 @@ static int qcom_pcie_ep_probe(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
-	ret = qcom_pcie_enable_resources(pcie_ep);
-	if (ret) {
-		dev_err(dev, "Failed to enable resources: %d\n", ret);
-		return ret;
-	}
-
 	ret = dw_pcie_ep_init(&pcie_ep->pci.ep);
 	if (ret) {
 		dev_err(dev, "Failed to initialize endpoint: %d\n", ret);
-		goto err_disable_resources;
+		return ret;
 	}
 
 	ret = qcom_pcie_ep_enable_irq_resources(pdev, pcie_ep);
 	if (ret)
-		goto err_disable_resources;
+		goto err_ep_deinit;
 
 	name = devm_kasprintf(dev, GFP_KERNEL, "%pOFP", dev->of_node);
 	if (!name) {
@@ -877,8 +871,8 @@ static int qcom_pcie_ep_probe(struct platform_device *pdev)
 	disable_irq(pcie_ep->global_irq);
 	disable_irq(pcie_ep->perst_irq);
 
-err_disable_resources:
-	qcom_pcie_disable_resources(pcie_ep);
+err_ep_deinit:
+	dw_pcie_ep_deinit(&pcie_ep->pci.ep);
 
 	return ret;
 }
-- 
2.25.1