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PCI: qcom: Handle mixed PERST#/PHY DT configuration

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The driver currently supports two PERST# and PHY DT configurations. In one
case, PHY and 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 fail 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>
[mani: folded the fix: https://lore.kernel.org/linux-pci/20260526-fix_perst_gpio_handling-v1-1-9170507bb4e9@oss.qualcomm.com]
Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
Link: https://patch.msgid.link/20260508-mix_perst_phy_dts-v1-1-9eff6ee9b51a@oss.qualcomm.com
This commit is contained in:
Qiang Yu 2026-05-08 02:54:19 -07:00 committed by Manivannan Sadhasivam
parent 2cc0e7454c
commit 1a23bcb452
1 changed files with 17 additions and 6 deletions
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23
drivers/pci/controller/dwc/pcie-qcom.c
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@ -289,6 +289,7 @@ struct qcom_pcie {
const struct qcom_pcie_cfg *cfg;
struct dentry *debugfs;
struct list_head ports;
struct gpio_desc *reset;
bool use_pm_opp;
};
@ -1798,6 +1799,13 @@ static int qcom_pcie_parse_perst(struct qcom_pcie *pcie,
struct gpio_desc *reset;
int ret;
if (pcie->reset) {
dev_warn_once(dev,
"Reusing PERST# from Root Complex node. DT needs to be fixed!\n");
reset = pcie->reset;
goto skip_perst_parsing;
}
if (!of_find_property(np, "reset-gpios", NULL))
goto parse_child_node;
@ -1816,6 +1824,7 @@ 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;
@ -1873,6 +1882,13 @@ 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);
}
for_each_available_child_of_node_scoped(dev->of_node, of_port) {
if (!of_node_is_type(of_port, "pci"))
continue;
@ -1899,7 +1915,6 @@ static int qcom_pcie_parse_legacy_binding(struct qcom_pcie *pcie)
struct device *dev = pcie->pci->dev;
struct qcom_pcie_perst *perst;
struct qcom_pcie_port *port;
struct gpio_desc *reset;
struct phy *phy;
int ret;
@ -1907,10 +1922,6 @@ static int qcom_pcie_parse_legacy_binding(struct qcom_pcie *pcie)
if (IS_ERR(phy))
return PTR_ERR(phy);
reset = devm_gpiod_get_optional(dev, "perst", GPIOD_OUT_HIGH);
if (IS_ERR(reset))
return PTR_ERR(reset);
ret = phy_init(phy);
if (ret)
return ret;
@ -1927,7 +1938,7 @@ static int qcom_pcie_parse_legacy_binding(struct qcom_pcie *pcie)
INIT_LIST_HEAD(&port->list);
list_add_tail(&port->list, &pcie->ports);
perst->desc = reset;
perst->desc = pcie->reset;
INIT_LIST_HEAD(&port->perst);
INIT_LIST_HEAD(&perst->list);
list_add_tail(&perst->list, &port->perst);