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

[Manikanta Maddireddy <mmaddireddy@nvidia.com>]

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@nvidia.com>
>>>>
>>>> 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

-- 
nvpublic