On Wed, Mar 1, 2023 at 5:55 PM AngeloGioacchino Del Regno
<angelogioacchino.delregno@xxxxxxxxxxxxx> 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@xxxxxxxxxxxxx>
> ---
> 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.
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.
ChenYu
> +};
> +
> &mt6359_vufs_ldo_reg {
> regulator-always-on;
> };
> @@ -1411,6 +1418,8 @@ mt6315_7_vbuck1: vbuck1 {
> regulator-max-microvolt = <800000>;
> 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
>
