linux-kernel - Re: [PATCH 0/2] MT8195 Cherry: Assign MFG vregs for power saving

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Message-ID: <CAGXv+5FWPZYjsXse58k5HyMijkrKBDYw0k4wpdfGv99ur8=5yg@mail.gmail.com>
Date:   Tue, 31 Oct 2023 17:19:37 +0800
From:   Chen-Yu Tsai <wenst@...omium.org>
To:     AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
Cc:     matthias.bgg@...il.com, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, kernel@...labora.com
Subject: Re: [PATCH 0/2] MT8195 Cherry: Assign MFG vregs for power saving

On Mon, Oct 30, 2023 at 9:25 PM AngeloGioacchino Del Regno
<angelogioacchino.delregno@...labora.com> wrote:
>
> This series assigns the right regulators to MFG0 and MFG1, respectively
> VGPU (GPU Core) and VSRAM_OTHERS (GPU SRAM), and removes the property
> regulator-always-on from both.
>
> This allows to save power both during runtime suspend and during system
> sleep; specifically because:
>  1. The GPU SRAM regulator is switched off during runtime suspend
>  2. The GPU Core regulator is switched off during system sleep
>
> Of course, in order for those power saving actions to actually take
> place, it is required to also have the code in [1].
> Anyway, even without series [1], this will not introduce any unstability
> as the Vgpu regulator will simply not ever get turned off.
>
> [1]: https://lore.kernel.org/r/20231030132257.85379-1-angelogioacchino.delregno@collabora.com
>
> AngeloGioacchino Del Regno (2):
>   arm64: dts: mediatek: mt8195-cherry: Add MFG0 domain supply
>   arm64: dts: mediatek: mt8195-cherry: Assign sram supply to MFG1 pd

Tested-by: Chen-Yu Tsai <wenst@...omium.org>

on Tomato without the power saving patches. Regulators are correctly
requested and I can see the SRAM regulator get turned on and off with
GPU usage.