Re: [PATCH v1 1/2] arm64: dts: mediatek: mt8195: Add subsys clks for PCIe power domains

[AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>]

Il 02/04/25 11:34, Chen-Yu Tsai ha scritto:
> On Wed, Apr 2, 2025 at 5:10 PM AngeloGioacchino Del Regno
> <angelogioacchino.delregno@collabora.com> wrote:
>>
>> The PCIe MAC needs the sram to be powered on for internal IP
>> access and it has always worked before because the bootloader
>> on Chromebooks was leaving the PCIe PERI_AO MEM clocks on
>> before booting the kernel.
>> Add the SRAM (mem) clock as a subsystem clock on the PCIe MAC
>> P0 and P1 to correctly describe the hardware and to avoid any
>> issue with bootloaders behaving differently.
>>
>> Fixes: 2b515194bf0c ("arm64: dts: mt8195: Add power domains controller")
>> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
>> ---
>>   arch/arm64/boot/dts/mediatek/mt8195.dtsi | 4 ++++
>>   1 file changed, 4 insertions(+)
>>
>> diff --git a/arch/arm64/boot/dts/mediatek/mt8195.dtsi b/arch/arm64/boot/dts/mediatek/mt8195.dtsi
>> index b33726da900b..0cb96cba727a 100644
>> --- a/arch/arm64/boot/dts/mediatek/mt8195.dtsi
>> +++ b/arch/arm64/boot/dts/mediatek/mt8195.dtsi
>> @@ -792,12 +792,16 @@ power-domain@MT8195_POWER_DOMAIN_CAM_MRAW {
>>
>>                                  power-domain@MT8195_POWER_DOMAIN_PCIE_MAC_P0 {
>>                                          reg = <MT8195_POWER_DOMAIN_PCIE_MAC_P0>;
>> +                                       clocks = <&pericfg_ao CLK_PERI_AO_PCIE_P0_MEM>;
>> +                                       clock-names = "ss-pextp0-mem";
> 
> Doesn't the PCIe host controller already reference this clock?
> 
>>                                          mediatek,infracfg = <&infracfg_ao>;
>>                                          #power-domain-cells = <0>;
>>                                  };
>>
>>                                  power-domain@MT8195_POWER_DOMAIN_PCIE_MAC_P1 {
>>                                          reg = <MT8195_POWER_DOMAIN_PCIE_MAC_P1>;
>> +                                       clocks = <&pericfg_ao CLK_PERI_AO_PCIE_P1_MEM>;
>> +                                       clock-names = "ss-pextp1-mem";
> 
> Not this one though, since:
> 
>           /* Designer has connect pcie1 with peri_mem_p0 clock */
>           <&pericfg_ao CLK_PERI_AO_PCIE_P0_MEM>;
> 

I'm not sure what this comment refers to - as in, whether this is referring
to the board designer or to the SoC//IP designer...

...but if MediaTek can clarify, I'd be happy :-)

Cheers,
Angelo

> 
> ChenYu
> 
>>                                          mediatek,infracfg = <&infracfg_ao>;
>>                                          #power-domain-cells = <0>;
>>                                  };
>> --
>> 2.48.1
>>
>>