linux-kernel - [PATCH 08/11] PCI: qcom-ep: Make PERST separation optional

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Date:   Fri, 26 Aug 2022 23:49:20 +0530
From:   Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To:     lpieralisi@...nel.org, robh@...nel.org, andersson@...nel.org
Cc:     kw@...ux.com, bhelgaas@...gle.com, linux-pci@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        konrad.dybcio@...ainline.org, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, devicetree@...r.kernel.org,
        dmitry.baryshkov@...aro.org,
        Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Subject: [PATCH 08/11] PCI: qcom-ep: Make PERST separation optional

PERST separation is an optional debug feature used to collect the crash
dump from the PCIe endpoint devices by the PCIe host when the endpoint
crashes. This feature keeps the PCIe link up by separating the PCIe IP
block from the SoC reset logic.

Hence, make the property optional in the driver.

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
---
 drivers/pci/controller/dwc/pcie-qcom-ep.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-qcom-ep.c b/drivers/pci/controller/dwc/pcie-qcom-ep.c
index 54ac2fef8b88..4908f08bd90b 100644
--- a/drivers/pci/controller/dwc/pcie-qcom-ep.c
+++ b/drivers/pci/controller/dwc/pcie-qcom-ep.c
@@ -216,8 +216,10 @@ static int qcom_pcie_ep_core_reset(struct qcom_pcie_ep *pcie_ep)
  */
 static void qcom_pcie_ep_configure_tcsr(struct qcom_pcie_ep *pcie_ep)
 {
-	regmap_write(pcie_ep->perst_map, pcie_ep->perst_en, 0);
-	regmap_write(pcie_ep->perst_map, pcie_ep->perst_sep_en, 0);
+	if (pcie_ep->perst_map) {
+		regmap_write(pcie_ep->perst_map, pcie_ep->perst_en, 0);
+		regmap_write(pcie_ep->perst_map, pcie_ep->perst_sep_en, 0);
+	}
 }
 
 static int qcom_pcie_dw_link_up(struct dw_pcie *pci)
@@ -463,8 +465,8 @@ static int qcom_pcie_ep_get_io_resources(struct platform_device *pdev,
 
 	syscon = of_parse_phandle(dev->of_node, "qcom,perst-regs", 0);
 	if (!syscon) {
-		dev_err(dev, "Failed to parse qcom,perst-regs\n");
-		return -EINVAL;
+		dev_dbg(dev, "PERST separation not available\n");
+		return 0;
 	}
 
 	pcie_ep->perst_map = syscon_node_to_regmap(syscon);
-- 
2.25.1