Re: [PATCH for-5.4.y] drm/msm/dsi: Enable runtime PM

[Dmitry Baryshkov <dmitry.baryshkov@linaro.org>]

On Mon, 29 Jan 2024 at 07:46, Amit Pundir <amit.pundir@linaro.org> wrote:
>
> From: Konrad Dybcio <konrad.dybcio@linaro.org>
>
> [ Upstream commit 6ab502bc1cf3147ea1d8540d04b83a7a4cb6d1f1 ]
>
> Some devices power the DSI PHY/PLL through a power rail that we model
> as a GENPD. Enable runtime PM to make it suspendable.
>
> Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> Patchwork: https://patchwork.freedesktop.org/patch/543352/
> Link: https://lore.kernel.org/r/20230620-topic-dsiphy_rpm-v2-2-a11a751f34f0@linaro.org
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> Stable-dep-of: 3d07a411b4fa ("drm/msm/dsi: Use pm_runtime_resume_and_get to prevent refcnt leaks")
> Signed-off-by: Amit Pundir <amit.pundir@linaro.org>
> ---
> Rebased to v5.4.y: s/devm_pm_runtime_enable/pm_runtime_enable

This leaks pm runtime enablement past the DSI PHY probe/remove cycle.
Either the devm_pm_runtime_enable() API should be included into the
backport, or ite emulation via devm_add_action_or_reset().

>
> Alternate solution maybe to revert the problematic commit 31b169a8bed7
> ("drm/msm/dsi: Use pm_runtime_resume_and_get to prevent refcnt leaks")
> from v5.4.y which broke display on DB845c.
>
>  drivers/gpu/drm/msm/dsi/phy/dsi_phy.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/drivers/gpu/drm/msm/dsi/phy/dsi_phy.c b/drivers/gpu/drm/msm/dsi/phy/dsi_phy.c
> index 1582386fe162..30f07b8a5421 100644
> --- a/drivers/gpu/drm/msm/dsi/phy/dsi_phy.c
> +++ b/drivers/gpu/drm/msm/dsi/phy/dsi_phy.c
> @@ -606,6 +606,8 @@ static int dsi_phy_driver_probe(struct platform_device *pdev)
>                         goto fail;
>         }
>
> +       pm_runtime_enable(&pdev->dev);
> +
>         /* PLL init will call into clk_register which requires
>          * register access, so we need to enable power and ahb clock.
>          */
> --
> 2.25.1
>


-- 
With best wishes
Dmitry