Re: [PATCH v2] arm64: dts: rockchip: Add missing pinctrl for PCIe30x4 node

[Alex Bee <knaerzche@gmail.com>]

Am 11.07.24 um 11:17 schrieb Chen-Yu Tsai:
> On Thu, Jul 11, 2024 at 4:44 PM Jonas Karlman <jonas@kwiboo.se> wrote:
>>
>> Hi Anand,
>>
>> On 2024-07-11 08:09, Anand Moon wrote:
>>> Add missing pinctrl settings for PCIe 3.0 x4 clock request and wake
>>> signals.Each component of PCIe communication have the following control
>>> signals: PERST, WAKE, CLKREQ, and REFCLK. These signals work to generate
>>> high-speed signals and communicate with other PCIe devices.
>>> Used by root complex to endpoint depending on the power state.
>>>
>>> PERST is referred to as a fundamental reset. PERST should be held low
>>> until all the power rails in the system and the reference clock are stable.
>>> A transition from low to high in this signal usually indicates the
>>> beginning of link initialization.
>>>
>>> WAKE signal is an active-low signal that is used to return the PCIe
>>> interface to an active state when in a low-power state.
>>>
>>> CLKREQ signal is also an active-low signal and is used to request the
>>> reference clock.
>>>
>>> Signed-off-by: Anand Moon <linux.amoon@gmail.com>
>>> ---
>>> V2: Update the commit messge to describe the changs.
>>>      use pinctl group as its pre define in pinctl dtsi
>>> ---
>>>   arch/arm64/boot/dts/rockchip/rk3588-rock-5b.dts | 6 +-----
>>>   1 file changed, 1 insertion(+), 5 deletions(-)
>>>
>>> diff --git a/arch/arm64/boot/dts/rockchip/rk3588-rock-5b.dts b/arch/arm64/boot/dts/rockchip/rk3588-rock-5b.dts
>>> index 2e7512676b7e..ab3a20986c6a 100644
>>> --- a/arch/arm64/boot/dts/rockchip/rk3588-rock-5b.dts
>>> +++ b/arch/arm64/boot/dts/rockchip/rk3588-rock-5b.dts
>>> @@ -301,7 +301,7 @@ &pcie30phy {
>>>
>>>   &pcie3x4 {
>>>        pinctrl-names = "default";
>>> -     pinctrl-0 = <&pcie3_rst>;
>>> +     pinctrl-0 = <&pcie30x4m1_pins>;
>>
>> Use of the existing pcie30x4m1_pins group may not be fully accurate for
>> the PERST pin. The use of reset-gpios indicate that the PERST pin is
>> used with GPIO function and the driver will implicitly change the
>> function from perstn_m1 to GPIO. So this may not be best representation
>> of the hw, hence my initial suggestion, something like:
>>
>>          pcie30x4_pins: pcie30x4-pins {
>>                  rockchip,pins =
>>                          <4 RK_PB4 4 &pcfg_pull_none>,
>>                          <4 RK_PB6 RK_FUNC_GPIO &pcfg_pull_none>,
>>                          <4 RK_PB5 4 &pcfg_pull_none>;
>>          };
>>
>> Similar change should probably also be done for pcie2x1l0 and pcie2x1l2,
>> not just pcie3x4.
> 
> Can we consider implementing strict mode in the pinctrl driver so we don't
> have to keep doing this GPIO + pinmux dance?
> 

This is not about drivers, this is DT which is independent from drivers.
Jonas and I had discussion recently on u-boot mailing list with somebody
using Open/FreeBSD about exact that topic. Pinctrl mux settings should be
very explicit, even if it is not required by the linux-driver.

Alex

> ChenYu
> 
> 
>> Regards,
>> Jonas
>>
>>>        reset-gpios = <&gpio4 RK_PB6 GPIO_ACTIVE_HIGH>;
>>>        vpcie3v3-supply = <&vcc3v3_pcie30>;
>>>        status = "okay";
>>> @@ -341,10 +341,6 @@ pcie2_2_rst: pcie2-2-rst {
>>>        };
>>>
>>>        pcie3 {
>>> -             pcie3_rst: pcie3-rst {
>>> -                     rockchip,pins = <4 RK_PB6 RK_FUNC_GPIO &pcfg_pull_none>;
>>> -             };
>>> -
>>>                pcie3_vcc3v3_en: pcie3-vcc3v3-en {
>>>                        rockchip,pins = <1 RK_PA4 RK_FUNC_GPIO &pcfg_pull_none>;
>>>                };
>>>
>>> base-commit: 34afb82a3c67f869267a26f593b6f8fc6bf35905
>>
>>
> 
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