linux-kernel - Re: [PATCH] arm64: dts: mt8192: Add adsp power domain controller

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Message-ID: <8ae2a510-abf6-6e1b-9893-293db7d930e7@collabora.com>
Date:   Thu, 1 Dec 2022 10:39:32 +0100
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
To:     Chen-Yu Tsai <wenst@...omium.org>
Cc:     Allen-KH Cheng <allen-kh.cheng@...iatek.com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Project_Global_Chrome_Upstream_Group@...iatek.com,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, linux-mediatek@...ts.infradead.org
Subject: Re: [PATCH] arm64: dts: mt8192: Add adsp power domain controller

Il 01/12/22 10:10, Chen-Yu Tsai ha scritto:
> On Thu, Dec 1, 2022 at 5:07 PM AngeloGioacchino Del Regno
> <angelogioacchino.delregno@...labora.com> wrote:
>>
>> Il 01/12/22 08:33, Allen-KH Cheng ha scritto:
>>> Add adsp power domain controller node for mt8192 SoC.
>>>
>>> Signed-off-by: Allen-KH Cheng <allen-kh.cheng@...iatek.com>
>>> ---
>>> Ref: https://lore.kernel.org/all/2ec80bd8-dfef-d2e6-eb41-6e6088043e33@collabora.com/
>>>       [Allen-KH Cheng <allen-kh.cheng@...iatek.com>]
>>> ---
>>> ---
>>>    arch/arm64/boot/dts/mediatek/mt8192.dtsi | 8 ++++++++
>>>    include/dt-bindings/power/mt8192-power.h | 1 +
>>>    2 files changed, 9 insertions(+)
>>>
>>
>> Allen, thanks for this one, but it's incomplete...
>>
>> First of all, you must add the power domain on the driver itself, specifically,
>> in drivers/soc/mediatek/mt8192-pm-domains.h - otherwise this change will have no
>> effect!
> 
> Actually it's worse. The driver doesn't know about the new power domain,
> and so it will fail to probe. We might need to make the power domain driver
> fail gracefully and skip unknown power domains.
> 

Right. It's worse. I don't know, though, if gracefully skipping unknown power
domains in the driver would be a good decision... as sometimes error messages
go unnoticed.

When the platform "explodes" instead, you're forced to read that log carefully
and get it working again... Anyway, I'm only thinking out loud, nothing less and
nothing more than that :-)

By the way, we can probably expand on that topic a bit later, as it's outside of
the scope of this specific change.

Back to topic, if we get one series containing both changes (devicetree, bindings
and driver) with the right Fixes tags and/or Cc stable, we shouldn't have such
issue on backports so we can probably ignore that potential issue, I think? :-)

Cheers,
Angelo

> ChenYu
> 
>> ...Then, as Chen-Yu said, you should also add the power domain to the scp_adsp
>> clock node as that's solving the lockup issue...
>>
>> .......and last, but not least: we need a Fixes tag to backport this fix, here
>> and on the commit that adds the missing power domain in the driver.
>>
>> Thanks,
>> Angelo
>>
>>> diff --git a/arch/arm64/boot/dts/mediatek/mt8192.dtsi b/arch/arm64/boot/dts/mediatek/mt8192.dtsi
>>> index 424fc89cc6f7..e71afba871fc 100644
>>> --- a/arch/arm64/boot/dts/mediatek/mt8192.dtsi
>>> +++ b/arch/arm64/boot/dts/mediatek/mt8192.dtsi
>>> @@ -514,6 +514,14 @@
>>>                                                };
>>>                                        };
>>>                                };
>>> +
>>> +                             power-domain@...192_POWER_DOMAIN_ADSP {
>>> +                                     reg = <MT8192_POWER_DOMAIN_ADSP>;
>>> +                                     clocks = <&topckgen CLK_TOP_ADSP_SEL>;
>>> +                                     clock-names = "adsp";
>>> +                                     mediatek,infracfg = <&infracfg>;
>>> +                                     #power-domain-cells = <0>;
>>> +                             };
>>>                        };
>>>                };
>>>
>>> diff --git a/include/dt-bindings/power/mt8192-power.h b/include/dt-bindings/power/mt8192-power.h
>>> index 4eaa53d7270a..63e81cd0d06d 100644
>>> --- a/include/dt-bindings/power/mt8192-power.h
>>> +++ b/include/dt-bindings/power/mt8192-power.h
>>> @@ -28,5 +28,6 @@
>>>    #define MT8192_POWER_DOMAIN_CAM_RAWA        18
>>>    #define MT8192_POWER_DOMAIN_CAM_RAWB        19
>>>    #define MT8192_POWER_DOMAIN_CAM_RAWC        20
>>> +#define MT8192_POWER_DOMAIN_ADSP     21
>>>
>>>    #endif /* _DT_BINDINGS_POWER_MT8192_POWER_H */
>>>
>>