From: Qiang Yu <qiang.yu@oss.qualcomm.com>
To: "Manivannan Sadhasivam" <mani@kernel.org>,
"Lorenzo Pieralisi" <lpieralisi@kernel.org>,
"Krzysztof Wilczyński" <kwilczynski@kernel.org>,
"Rob Herring" <robh@kernel.org>,
"Bjorn Helgaas" <bhelgaas@google.com>
Cc: linux-arm-msm@vger.kernel.org, linux-pci@vger.kernel.org,
linux-kernel@vger.kernel.org,
Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>,
Qiang Yu <qiang.yu@oss.qualcomm.com>
Subject: [PATCH] PCI: qcom: Handle mixed PERST#/PHY DT configuration
Date: Fri, 08 May 2026 02:54:19 -0700 [thread overview]
Message-ID: <20260508-mix_perst_phy_dts-v1-1-9eff6ee9b51a@oss.qualcomm.com> (raw)
The driver currently supports two PERST# and PHY DT configuration. In one
case, PHY, PERST#, are described in the RC node. In the other case, they
are described in the RP node.
A mixed setup is not supported. One common example is PHY on the RP node
while PERST# remains on the RC node. In that case the driver goes through
the RP parse path, does not find PERST# on RP, and does not report an
error because PERST# is optional. Probe can then succeed silently while
PERST# is left uncontrolled, and PCIe endpoints fails to work later. This
silent probe success makes debugging difficult.
Handle this mixed case in the RP parse path by checking whether PERST# is
present on RC and, if so, using the RC PERST# GPIO for RP ports while
keeping RP parsing for PHY. Emit a warning to indicate mixed DT content so
it can be fixed.
This keeps mixed systems functional and makes the configuration issue
visible instead of failing later at endpoint bring-up.
Suggested-by: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>
Signed-off-by: Qiang Yu <qiang.yu@oss.qualcomm.com>
---
drivers/pci/controller/dwc/pcie-qcom.c | 15 +++++++++++++++
1 file changed, 15 insertions(+)
diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
index 9fdfc88ac151..8235961d692f 100644
--- a/drivers/pci/controller/dwc/pcie-qcom.c
+++ b/drivers/pci/controller/dwc/pcie-qcom.c
@@ -282,6 +282,7 @@ struct qcom_pcie {
const struct qcom_pcie_cfg *cfg;
struct dentry *debugfs;
struct list_head ports;
+ struct gpio_desc *reset;
bool suspended;
bool use_pm_opp;
};
@@ -1703,6 +1704,11 @@ static int qcom_pcie_parse_perst(struct qcom_pcie *pcie,
struct gpio_desc *reset;
int ret;
+ if (pcie->reset) {
+ reset = pcie->reset;
+ goto skip_perst_parsing;
+ }
+
if (!of_find_property(np, "reset-gpios", NULL))
goto parse_child_node;
@@ -1721,6 +1727,7 @@ static int qcom_pcie_parse_perst(struct qcom_pcie *pcie,
return PTR_ERR(reset);
}
+skip_perst_parsing:
perst = devm_kzalloc(dev, sizeof(*perst), GFP_KERNEL);
if (!perst)
return -ENOMEM;
@@ -1778,6 +1785,14 @@ static int qcom_pcie_parse_ports(struct qcom_pcie *pcie)
struct device *dev = pcie->pci->dev;
int ret = -ENODEV;
+ if (of_find_property(dev->of_node, "perst-gpios", NULL)) {
+ pcie->reset = devm_gpiod_get_optional(dev, "perst", GPIOD_OUT_HIGH);
+ if (IS_ERR(pcie->reset))
+ return PTR_ERR(pcie->reset);
+
+ dev_warn(dev, "Reusing PERST# from Root Complex node. DT needs to be fixed!\n");
+ }
+
for_each_available_child_of_node_scoped(dev->of_node, of_port) {
if (!of_node_is_type(of_port, "pci"))
continue;
---
base-commit: 33a76fc3c3e61386524479b99f35423bd3d9a895
change-id: 20260508-mix_perst_phy_dts-b741b840833b
Best regards,
--
Qiang Yu <qiang.yu@oss.qualcomm.com>
next reply other threads:[~2026-05-08 9:54 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-08 9:54 Qiang Yu [this message]
2026-05-08 20:01 ` [PATCH] PCI: qcom: Handle mixed PERST#/PHY DT configuration sashiko-bot
2026-05-11 10:29 ` Konrad Dybcio
2026-05-15 16:52 ` Manivannan Sadhasivam
2026-05-31 11:07 ` Dmitry Baryshkov
2026-06-02 4:34 ` Kathiravan Thirumoorthy
2026-06-08 7:43 ` Dmitry Baryshkov
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