Re: [PATCH] arm64: dts: mediatek: mt8192-asurada: Add off-on-delay-us for pp3300_mipibrdg

[AngeloGioacchino Del Regno]

Il 29/04/24 11:53, Pin-yen Lin ha scritto:
> Set off-on-delay-us to 500000 us for pp3300_mipibrdg to make sure it
> complies with the panel sequence. Explicit configuration on the
> regulator node is required because mt8192-asurada uses the same power
> supply for the panel and the anx7625 DP bridge. So powering on/off the
> DP bridge could break the power sequence requirement for the panel.
>
> Fixes: f9f00b1f6b9b ("arm64: dts: mediatek: asurada: Add display regulators")
> Signed-off-by: Pin-yen Lin <treapking@xxxxxxxxxxxx>

Uhm, there might be more to it - I don't think that this should ever happen.

The regulator is refcounted, so...
 * Bridge on: panel goes off, but regulator doesn't turn off (refcount=1)
   * Panel resume -> sequence respected (refcount=2 -> wait -> more vregs, etc)
 * Bridge off: panel is already off (refcount=0)
   * Bridge resume -> refcount=1, no panel commands yet
   * Panel resume -> refcount=2, wait -> more vregs, etc

Can you please describe the issue that you're getting?

Cheers,
Angelo

> ---
>
>   arch/arm64/boot/dts/mediatek/mt8192-asurada.dtsi | 1 +
>   1 file changed, 1 insertion(+)
>
> diff --git a/arch/arm64/boot/dts/mediatek/mt8192-asurada.dtsi b/arch/arm64/boot/dts/mediatek/mt8192-asurada.dtsi
> index 7a704246678f..08d71ddf3668 100644
> --- a/arch/arm64/boot/dts/mediatek/mt8192-asurada.dtsi
> +++ b/arch/arm64/boot/dts/mediatek/mt8192-asurada.dtsi
> @@ -147,6 +147,7 @@ pp3300_mipibrdg: regulator-3v3-mipibrdg {
>   		regulator-boot-on;
>   		gpio = <&pio 127 GPIO_ACTIVE_HIGH>;
>   		vin-supply = <&pp3300_g>;
> +		off-on-delay-us = <500000>;
>   	};
>   
>   	/* separately switched 3.3V power rail */