linux-kernel - Re: [PATCH v2 1/8] arm64: dts: mediatek: cherry: Enable the System Companion Processor

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Message-ID: <94bea93e-484d-e635-4e94-5ffe14b127f4@collabora.com>
Date:   Mon, 25 Jul 2022 10:06:48 +0200
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
To:     Chen-Yu Tsai <wenst@...omium.org>,
        Tinghan Shen <tinghan.shen@...iatek.com>
Cc:     matthias.bgg@...il.com, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/8] arm64: dts: mediatek: cherry: Enable the System
 Companion Processor

Il 25/07/22 06:21, Chen-Yu Tsai ha scritto:
> On Thu, Jul 21, 2022 at 10:50 PM AngeloGioacchino Del Regno
> <angelogioacchino.delregno@...labora.com> wrote:
>>
>> MT8195 features a SCP like some other older SoCs, and Cherry uses it
>> for various tasks. Add the required pin configuration and DMA pool
>> and enable the node.
>>
>> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
>> ---
>>   .../boot/dts/mediatek/mt8195-cherry.dtsi      | 28 +++++++++++++++++++
>>   1 file changed, 28 insertions(+)
>>
>> diff --git a/arch/arm64/boot/dts/mediatek/mt8195-cherry.dtsi b/arch/arm64/boot/dts/mediatek/mt8195-cherry.dtsi
>> index fcc600674339..feebbe367e93 100644
>> --- a/arch/arm64/boot/dts/mediatek/mt8195-cherry.dtsi
>> +++ b/arch/arm64/boot/dts/mediatek/mt8195-cherry.dtsi
>> @@ -104,6 +104,18 @@ usb_vbus: regulator-5v0-usb-vbus {
>>                  enable-active-high;
>>                  regulator-always-on;
>>          };
>> +
>> +       reserved_memory: reserved-memory {
>> +               #address-cells = <2>;
>> +               #size-cells = <2>;
>> +               ranges;
>> +
>> +               scp_mem: memory@...00000 {
>> +                       compatible = "shared-dma-pool";
>> +                       reg = <0 0x50000000 0 0x2900000>;
>> +                       no-map;
>> +               };
>> +       };
>>   };
>>
>>   &i2c0 {
>> @@ -600,6 +612,14 @@ pins-low-power-pupd {
>>                  };
>>          };
>>
>> +       scp_pins: scp-default-pins {
>> +               pins-vreq {
>> +                       pinmux = <PINMUX_GPIO76__FUNC_SCP_VREQ_VAO>;
>> +                       bias-disable;
>> +                       input-enable;
>> +               };
>> +       };
>> +
>>          spi0_pins: spi0-default-pins {
>>                  pins-cs-mosi-clk {
>>                          pinmux = <PINMUX_GPIO132__FUNC_SPIM0_CSB>,
>> @@ -643,6 +663,14 @@ &pmic {
>>          interrupts-extended = <&pio 222 IRQ_TYPE_LEVEL_HIGH>;
>>   };
>>
>> +&scp {
>> +       status = "okay";
>> +
>> +       memory-region = <&scp_mem>;
>> +       pinctrl-names = "default";
>> +       pinctrl-0 = <&scp_pins>;
> 
> firmware-name = "mediatek/mt8195/scp.img";
> 

My intention was to actually add this line here. I must've erroneously
dropped it during cleanup/rebase...

> Or maybe this should be added to the base mt8195.dtsi?
> 
> The entry for mt8192 was added to mt8192-asurada.dtsi though.
> 
> Tinghan, could you ask internally whether the SCP firmware should be
> tied to the SoC or the projects involving the SoC?

In my opinion, even if that may be tied to the SoCs, we should still declare
it in the machine(/platform) devicetree as (even if *luckily* this is not the
case on Chromebooks), firmwares may be signed with a OEM key and may differ
just for that.

I'll send a v3 with that fix ASAP.

Cheers,
Angelo

> 
> Thanks
> ChenYu
> 
>> +};
>> +
>>   &spi0 {
>>          status = "okay";
>>
>> --
>> 2.35.1
>>
>>