Messages in this thread | | | Date | Tue, 7 Mar 2023 10:30:04 +0100 | Subject | Re: [PATCH v4 12/19] arm64: dts: mediatek: mt8192-asurada: Couple VGPU and VSRAM_OTHER regulators | From | AngeloGioacchino Del Regno <> |
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Il 07/03/23 10:24, Chen-Yu Tsai ha scritto: > On Fri, Mar 3, 2023 at 12:09 PM Chen-Yu Tsai <wenst@chromium.org> wrote: >> >> On Thu, Mar 2, 2023 at 6:17 PM AngeloGioacchino Del Regno >> <angelogioacchino.delregno@collabora.com> wrote: >>> >>> Il 02/03/23 11:03, Chen-Yu Tsai ha scritto: >>>> On Wed, Mar 1, 2023 at 5:55 PM AngeloGioacchino Del Regno >>>> <angelogioacchino.delregno@collabora.com> wrote: >>>>> >>>>> Add coupling for these regulators, as VSRAM_OTHER is used to power the >>>>> GPU SRAM, and they have a strict voltage output relation to satisfy in >>>>> order to ensure GPU stable operation. >>>>> While at it, also add voltage constraint overrides for the GPU SRAM >>>>> regulator "mt6359_vsram_others" so that we stay in a safe range of >>>>> 0.75-0.80V. >>>>> >>>>> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> >>>>> --- >>>>> arch/arm64/boot/dts/mediatek/mt8192-asurada.dtsi | 9 +++++++++ >>>>> 1 file changed, 9 insertions(+) >>>>> >>>>> diff --git a/arch/arm64/boot/dts/mediatek/mt8192-asurada.dtsi b/arch/arm64/boot/dts/mediatek/mt8192-asurada.dtsi >>>>> index 8570b78c04a4..f858eca219d7 100644 >>>>> --- a/arch/arm64/boot/dts/mediatek/mt8192-asurada.dtsi >>>>> +++ b/arch/arm64/boot/dts/mediatek/mt8192-asurada.dtsi >>>>> @@ -447,6 +447,13 @@ &mt6359_vrf12_ldo_reg { >>>>> regulator-always-on; >>>>> }; >>>>> >>>>> +&mt6359_vsram_others_ldo_reg { >>>>> + regulator-min-microvolt = <750000>; >>>>> + regulator-max-microvolt = <800000>; >>>>> + regulator-coupled-with = <&mt6315_7_vbuck1>; >>>>> + regulator-coupled-max-spread = <10000>; >>>> >>>> Looking again at the downstream OPP table, it seems there's no voltage >>>> difference requirement. It only needs V_SRAM >= V_GPU. Same applies to >>>> MT8195. Looks like only MT8183 and MT8186 need V_SRAM - V_GPU >= 10000. >>> >>> On MT8195 we don't need any regulator coupling. There, the GPU-SRAM voltage >>> is fixed at .. I don't remember, 0.7V? - anyway - MT8195 doesn't need to >>> scale the vsram. >> >> Looks like it's fixed at 0.75V. I guess we're Ok on MT8195. >> >>>> >>>> Would setting max-spread to 0 work? I ask because with both regulator's >>>> maximum voltage set to 0.8V, there's no way we can reach the highest >>>> OPP. >>>> >>> >>> No that doesn't work. I can raise the Vgpu max voltage to 0.88V to solve the >>> issue right here and right now, or we can leave it like that and revisit it >>> later. >>> >>> I would at this point go for setting mt6315_7_vbuck1's max-microvolt to >>> 880000, as this is the maximum recommended voltage for the GPU as per the >>> MT8192 datasheet, it would also make sense as we would be still describing >>> the hardware in a correct manner. >>> >>> What do you think? >> >> If it's just to accommodate the coupler stuff, I say just set the maximum >> at the lowest possible setting that satisfies the coupler constraint and >> granularity of the regulator. The regulator does 6250 uV steps, so I guess >> we could set the maximum at 812500 uV, with a comment stating the nominal >> voltage of 800000 uV and that the extra 12500 uV is to workaround coupler >> limitations. >> >> Does that sound OK? > > Even without changing anything, the coupler seems to work OK: > > vsram_others 1 1 0 normal 800mV > 0mA 750mV 800mV > 10006000.syscon:power-controller-domain 1 > 0mA 0mV 0mV > Vgpu 2 2 0 normal 800mV > 0mA 606mV 800mV > 13000000.gpu-mali 1 > 0mA 800mV 800mV > 10006000.syscon:power-controller-domain 1 > 0mA 0mV 0mV > > Am I missing something? >
I don't think you are... I may be getting confused by all of the changesets that I'm pushing at once.
Hence, is this commit fine as it is?
Regards, Angelo
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