Messages in this thread | | | Date | Wed, 1 Mar 2023 10:30:25 +0100 | Subject | Re: [PATCH v3 11/18] arm64: dts: mediatek: mt8192-asurada: Couple VGPU and VSRAM_OTHER regulators | From | AngeloGioacchino Del Regno <> |
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Il 01/03/23 05:53, Chen-Yu Tsai ha scritto: > On Tue, Feb 28, 2023 at 6:47 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", but don't touch mt6315's vbuck1 as >> its constraints are fine. > > The minimum voltage on vbuck1 matches the lowest OPP. However the maximum > voltage is set to the maximum of the regulator itself. The MT8192 datasheet > says the absolute maximum for the GPU is 0.8V, and the recommended range > for 0.8V is 0.72V ~ 0.88V. The highest OPP we have is 0.8V, so I would > just set the maximum voltage to that? >
The point was that we'd never get vbuck1 at more than vsram+10mV because of the constraints that are set with regulator-coupled-max-spread, but thinking about it again, relying on that is *highly* suboptimal.
Yes, you're right, let's change the constraints on vbuck1 to 800mV: that's going to be for v4.
Thanks! Angelo
> ChenYu > >> 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 df477eb89f21..c8b6e1a9605b 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 = <850000>; >> + regulator-coupled-with = <&mt6315_7_vbuck1>; >> + regulator-coupled-max-spread = <10000>; >> +}; >> + >> &mt6359_vufs_ldo_reg { >> regulator-always-on; >> }; >> @@ -1411,6 +1418,8 @@ mt6315_7_vbuck1: vbuck1 { >> regulator-max-microvolt = <1193750>; >> regulator-enable-ramp-delay = <256>; >> regulator-allowed-modes = <0 1 2>; >> + regulator-coupled-with = <&mt6359_vsram_others_ldo_reg>; >> + regulator-coupled-max-spread = <10000>; >> }; >> }; >> }; >> -- >> 2.39.2 >>
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