On 27/09/2021 13:37, Guilherme G. Piccoli wrote:
> Commit 2317b87a2a6f ("arm64: dts: qcom: db820c: Add vdd_gfx and tie it into mmcc")
> introduced this voltage regulator which seems to be essential for the GPU,
> according to the board schematics [0]. The problem is that such commit sets
> the regulator min/max voltage range to a static value, which is a bit lower than
> the range supported to such regulator [1]. With that, the GPU is not stable
> as per my experiments (in a Dragonboard 820c-based board) - I've observed
> sudden reboots into a FW bad state.
>
> More than that, my experiment showed that this regulator must be set to
> always-on - this idea came from a commit in Linaro's tree, from Rajendra [2].
> With the voltage range updated plus set as always-on, the GPU is working
> correctly, in a stable fashion.
>
> [0] See page 9 (VDD_GFX), at
> https://www.96boards.org/documentation/consumer/dragonboard/dragonboard820c/hardware-docs/files/db820c-schematics.pdf
>
> [1] See section 3.5.3 (FT-SMPS) in the "PMI8994/PMI8996 Power Management IC",
> at https://developer.qualcomm.com/download/sd820e/pmi8994pmi8996-power-management-ic-device-specification.pdf
>
> [2] https://git.linaro.org/landing-teams/working/qualcomm/kernel.git/commit/?h=release/qcomlt-4.14&id=75fb43f3a62
>
> Cc: Rajendra Nayak <rnayak@xxxxxxxxxxxxxx>
> Cc: Vinod Koul <vkoul@xxxxxxxxxx>
> Fixes: 2317b87a2a6f ("arm64: dts: qcom: db820c: Add vdd_gfx and tie it into mmcc")
> Signed-off-by: Guilherme G. Piccoli <gpiccoli@xxxxxxxxxx>
> ---
>
> Hi Andy/Bjorn/all, this patch was tested in 5.14, but I've tested it
> in the linux-next tree as well and was able to apply there cleanly.
> I'm new in the DTS world, so my apologies in advance for any rookie
> mistake - suggestions are appreciated! Thanks in advance for the review,
>
>
> Guilherme
>
>
> arch/arm64/boot/dts/qcom/apq8096-db820c.dtsi | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm64/boot/dts/qcom/apq8096-db820c.dtsi b/arch/arm64/boot/dts/qcom/apq8096-db820c.dtsi
> index 51e17094d7b1..977842068619 100644
> --- a/arch/arm64/boot/dts/qcom/apq8096-db820c.dtsi
> +++ b/arch/arm64/boot/dts/qcom/apq8096-db820c.dtsi
> @@ -699,8 +699,11 @@ &pmi8994_spmi_regulators {
> vdd_gfx: s2@1700 {
> reg = <0x1700 0x100>;
> regulator-name = "VDD_GFX";
> - regulator-min-microvolt = <980000>;
> - regulator-max-microvolt = <980000>;
> + regulator-min-microvolt = <350000>;
> + regulator-max-microvolt = <1350000>;
> + regulator-always-on;
> + status = "okay";
> +
> };
> };
>
>
Sorry, due to a git bad config, it supressed all CCs - adding them now!
