Re: [PATCH] PCI: qcom: Handle mixed PERST#/PHY DT configuration

[Konrad Dybcio]

On 5/8/26 11:54 AM, Qiang Yu wrote:
> 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@xxxxxxxxxxxxxxxx>
> Signed-off-by: Qiang Yu <qiang.yu@xxxxxxxxxxxxxxxx>
> ---
>  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;

I'd rename this to make it more obvious it's at the RC node.. but
rc_reset doesn't really sound great..

otherwise:

Reviewed-by: Konrad Dybcio <konrad.dybcio@xxxxxxxxxxxxxxxx>

Konrad