2021-11-15 03:02:20

by cong yang

[permalink] [raw]
Subject: [PATCH] arm64: dts: sc7180: Fix ps8640 power sequence for Homestar rev4

When powering up the ps8640, we need to deassert PD right
after we turn on the vdd33 regulator. Unfortunately, the vdd33
regulator takes some time (~4ms) to turn on. Add in the delay
for the vdd33 regulator so that when the driver deasserts PD
that the regulator has had time to ramp.

Signed-off-by: yangcong <[email protected]>
---
arch/arm64/boot/dts/qcom/sc7180-trogdor-homestar-r4.dts | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/arch/arm64/boot/dts/qcom/sc7180-trogdor-homestar-r4.dts b/arch/arm64/boot/dts/qcom/sc7180-trogdor-homestar-r4.dts
index fb27106bbb4a..0de0c97f5728 100644
--- a/arch/arm64/boot/dts/qcom/sc7180-trogdor-homestar-r4.dts
+++ b/arch/arm64/boot/dts/qcom/sc7180-trogdor-homestar-r4.dts
@@ -15,3 +15,7 @@ / {
model = "Google Homestar (rev4+)";
compatible = "google,homestar", "qcom,sc7180";
};
+
+&pp3300_brij_ps8640 {
+ regulator-enable-ramp-delay = <4000>;
+};
--
2.25.1



2021-11-15 15:41:19

by Doug Anderson

[permalink] [raw]
Subject: Re: [PATCH] arm64: dts: sc7180: Fix ps8640 power sequence for Homestar rev4

Hi,

On Sun, Nov 14, 2021 at 7:02 PM yangcong
<[email protected]> wrote:
>
> When powering up the ps8640, we need to deassert PD right
> after we turn on the vdd33 regulator. Unfortunately, the vdd33
> regulator takes some time (~4ms) to turn on. Add in the delay
> for the vdd33 regulator so that when the driver deasserts PD
> that the regulator has had time to ramp.
>
> Signed-off-by: yangcong <[email protected]>
> ---
> arch/arm64/boot/dts/qcom/sc7180-trogdor-homestar-r4.dts | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/arch/arm64/boot/dts/qcom/sc7180-trogdor-homestar-r4.dts b/arch/arm64/boot/dts/qcom/sc7180-trogdor-homestar-r4.dts
> index fb27106bbb4a..0de0c97f5728 100644
> --- a/arch/arm64/boot/dts/qcom/sc7180-trogdor-homestar-r4.dts
> +++ b/arch/arm64/boot/dts/qcom/sc7180-trogdor-homestar-r4.dts
> @@ -15,3 +15,7 @@ / {
> model = "Google Homestar (rev4+)";
> compatible = "google,homestar", "qcom,sc7180";
> };
> +
> +&pp3300_brij_ps8640 {
> + regulator-enable-ramp-delay = <4000>;
> +};

It should have been pointed out somewhere in the post, but this patch
depends on Philip's most recent, which is:

https://lore.kernel.org/r/20211029152647.v3.4.If7aaa8e36f1269acae5488035bd62ce543756bf8@changeid/

This seems fine to me. Apparently this 4ms delay isn't needed
lazor-rev9 (at least they were happy with the signals on that board)
which is why this is a homestar change. That can make sense since the
components on the two boards may be different.

In any case:

Reviewed-by: Douglas Anderson <[email protected]>

2021-11-16 03:15:47

by Stephen Boyd

[permalink] [raw]
Subject: Re: [PATCH] arm64: dts: sc7180: Fix ps8640 power sequence for Homestar rev4

Quoting yangcong (2021-11-14 19:01:55)
> When powering up the ps8640, we need to deassert PD right
> after we turn on the vdd33 regulator. Unfortunately, the vdd33
> regulator takes some time (~4ms) to turn on. Add in the delay
> for the vdd33 regulator so that when the driver deasserts PD
> that the regulator has had time to ramp.
>
> Signed-off-by: yangcong <[email protected]>
> ---

Reviewed-by: Stephen Boyd <[email protected]>

2021-11-20 23:56:30

by Bjorn Andersson

[permalink] [raw]
Subject: Re: (subset) [PATCH] arm64: dts: sc7180: Fix ps8640 power sequence for Homestar rev4

On Mon, 15 Nov 2021 11:01:55 +0800, yangcong wrote:
> When powering up the ps8640, we need to deassert PD right
> after we turn on the vdd33 regulator. Unfortunately, the vdd33
> regulator takes some time (~4ms) to turn on. Add in the delay
> for the vdd33 regulator so that when the driver deasserts PD
> that the regulator has had time to ramp.
>
>
> [...]

Applied, thanks!

[1/1] arm64: dts: sc7180: Fix ps8640 power sequence for Homestar rev4
commit: 96e1e3a15273a99d89b1389e4487e734c7d37d8e

Best regards,
--
Bjorn Andersson <[email protected]>