Re: [PATCH v7 08/13] PCI: tegra194: Apply pinctrl settings for both PCIe RP and EP

[Manikanta Maddireddy]

On 16/03/26 7:01 am, Manivannan Sadhasivam wrote:
> On Sun, Mar 15, 2026 at 07:24:48PM +0530, Manikanta Maddireddy wrote:
> > On 05/03/26 3:49 pm, Manivannan Sadhasivam wrote:
> > > On Tue, Mar 03, 2026 at 12:24:43PM +0530, Manikanta Maddireddy wrote:
> > > > From: Vidya Sagar <vidyas@xxxxxxxxxx>
> > > >
> > > > PERST# and CLKREQ# pinctrl settings should be applied for both Root Port
> > > > and Endpoint mode. Move pinctrl_pm_select_default_state() function call
> > > > from Root Port specific configuration function to probe().
> > >
> > > Why should this driver care about setting default pinctrl state? Why can't it
> > > rely on the pinctrl framework as like other drivers?
> > >
> > > - Mani
> >
> > pinctrl framework doesn't know if PCIe controller is going to be configured
> > in Endpoint or Root port mode. In Root port mode PERST# signal should be
> > configured as special function IO pin(SFIO) and in Endpoint mode it should
> > be configured as general purpose IO pin(GPIO). So, PCIe driver should
> > request appropriate pinctl values.
>
> So you are saying that irrespective of board design, you can configure the
> controller in host/endpoint mode? Is it possible? Dual mode controllers are
> quite common in other SoCs, but they rely on devicetree to either configure the
> controller in host or endpoint mode.
>
> If the devicetree enables the endpoint node, why can't it also define the
> pinctrl config?
>
> - Mani

Root Port and Endpoint role switch is through device tree only.
pinctrl settings are defined in Root Port/Endpoint device tree node, but 
to apply the pinctrl settings respective driver need to call 
pinctrl_pm_select_default_state().

arch/arm64/boot/dts/nvidia/tegra234.dtsi

                pcie-ep@140e0000 {
                        compatible = "nvidia,tegra234-pcie-ep";
                        ...

                        pinctrl-names = "default";
                        pinctrl-0 = <&pex_rst_c10_in_state>;
                        ...
                }

arch/arm64/boot/dts/nvidia/tegra194.dtsi
                pcie@141a0000 {
                        compatible = "nvidia,tegra194-pcie";
                        ...

                        pinctrl-names = "default";
                        pinctrl-0 = <&pex_rst_c5_out_state>, 
<&pex_clkreq_c5_bi_dir_state>;
                        ...
                }
- Manikanta

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nvpublic