Re: [PATCH v2 1/3] drm/rockchip: dsi: Hold pm-runtime across bind/unbind

[Tom Hebb]

Reviewed-by: Thomas Hebb <tommyhebb@xxxxxxxxx>

Thank you for catching this, and sorry that my original fix broke things.
There had actually been a report of this breakage from my patch, but I
missed that email until it had already been merged and then didn't have
time to follow up on it. Totally my bad.

[Resending because my last reply was HTML.]

On Mon, Sep 27, 2021 at 11:00 AM Brian Norris <briannorris@xxxxxxxxxxxx> wrote:
>
> In commit 43c2de1002d2, we moved most HW configuration to bind(), but we
> didn't move the runtime PM management. Therefore, depending on initial
> boot state, runtime-PM workqueue delays, and other timing factors, we
> may disable our power domain in between the hardware configuration
> (bind()) and when we enable the display. This can cause us to lose
> hardware state and fail to configure our display. For example:
>
>   dw-mipi-dsi-rockchip ff968000.mipi: failed to write command FIFO
>   panel-innolux-p079zca ff960000.mipi.0: failed to write command 0
>
> or:
>
>   dw-mipi-dsi-rockchip ff968000.mipi: failed to write command FIFO
>   panel-kingdisplay-kd097d04 ff960000.mipi.0: failed write init cmds: -110
>
> We should match the runtime PM to the lifetime of the bind()/unbind()
> cycle.
>
> Tested on Acer Chrometab 10 (RK3399 Gru-Scarlet), with panel drivers
> built either as modules or built-in.
>
> Side notes: it seems one is more likely to see this problem when the
> panel driver is built into the kernel. I've also seen this problem
> bisect down to commits that simply changed Kconfig dependencies, because
> it changed the order in which driver init functions were compiled into
> the kernel, and therefore the ordering and timing of built-in device
> probe.
>
> Fixes: 43c2de1002d2 ("drm/rockchip: dsi: move all lane config except LCDC mux to bind()")
> Link: https://lore.kernel.org/linux-rockchip/9aedfb528600ecf871885f7293ca4207c84d16c1.camel@xxxxxxxxx/
> Reported-by: <aleksandr.o.makarov@xxxxxxxxx>
> Cc: <stable@xxxxxxxxxxxxxxx>
> Signed-off-by: Brian Norris <briannorris@xxxxxxxxxxxx>
> Tested-by: Nícolas F. R. A. Prado <nfraprado@xxxxxxxxxxxxx>
> ---
>
> Changes in v2:
> - Clean up pm-runtime state in error cases.
> - Correct git hash for Fixes.
>
>  .../gpu/drm/rockchip/dw-mipi-dsi-rockchip.c   | 37 ++++++++++---------
>  1 file changed, 19 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/gpu/drm/rockchip/dw-mipi-dsi-rockchip.c b/drivers/gpu/drm/rockchip/dw-mipi-dsi-rockchip.c
> index a2262bee5aa4..45676b23c019 100644
> --- a/drivers/gpu/drm/rockchip/dw-mipi-dsi-rockchip.c
> +++ b/drivers/gpu/drm/rockchip/dw-mipi-dsi-rockchip.c
> @@ -773,10 +773,6 @@ static void dw_mipi_dsi_encoder_enable(struct drm_encoder *encoder)
>         if (mux < 0)
>                 return;
>
> -       pm_runtime_get_sync(dsi->dev);
> -       if (dsi->slave)
> -               pm_runtime_get_sync(dsi->slave->dev);
> -
>         /*
>          * For the RK3399, the clk of grf must be enabled before writing grf
>          * register. And for RK3288 or other soc, this grf_clk must be NULL,
> @@ -795,20 +791,10 @@ static void dw_mipi_dsi_encoder_enable(struct drm_encoder *encoder)
>         clk_disable_unprepare(dsi->grf_clk);
>  }
>
> -static void dw_mipi_dsi_encoder_disable(struct drm_encoder *encoder)
> -{
> -       struct dw_mipi_dsi_rockchip *dsi = to_dsi(encoder);
> -
> -       if (dsi->slave)
> -               pm_runtime_put(dsi->slave->dev);
> -       pm_runtime_put(dsi->dev);
> -}
> -
>  static const struct drm_encoder_helper_funcs
>  dw_mipi_dsi_encoder_helper_funcs = {
>         .atomic_check = dw_mipi_dsi_encoder_atomic_check,
>         .enable = dw_mipi_dsi_encoder_enable,
> -       .disable = dw_mipi_dsi_encoder_disable,
>  };
>
>  static int rockchip_dsi_drm_create_encoder(struct dw_mipi_dsi_rockchip *dsi,
> @@ -938,10 +924,14 @@ static int dw_mipi_dsi_rockchip_bind(struct device *dev,
>                 put_device(second);
>         }
>
> +       pm_runtime_get_sync(dsi->dev);
> +       if (dsi->slave)
> +               pm_runtime_get_sync(dsi->slave->dev);
> +
>         ret = clk_prepare_enable(dsi->pllref_clk);
>         if (ret) {
>                 DRM_DEV_ERROR(dev, "Failed to enable pllref_clk: %d\n", ret);
> -               return ret;
> +               goto out_pm_runtime;
>         }
>
>         /*
> @@ -953,7 +943,7 @@ static int dw_mipi_dsi_rockchip_bind(struct device *dev,
>         ret = clk_prepare_enable(dsi->grf_clk);
>         if (ret) {
>                 DRM_DEV_ERROR(dsi->dev, "Failed to enable grf_clk: %d\n", ret);
> -               return ret;
> +               goto out_pm_runtime;
>         }
>
>         dw_mipi_dsi_rockchip_config(dsi);
> @@ -965,16 +955,23 @@ static int dw_mipi_dsi_rockchip_bind(struct device *dev,
>         ret = rockchip_dsi_drm_create_encoder(dsi, drm_dev);
>         if (ret) {
>                 DRM_DEV_ERROR(dev, "Failed to create drm encoder\n");
> -               return ret;
> +               goto out_pm_runtime;
>         }
>
>         ret = dw_mipi_dsi_bind(dsi->dmd, &dsi->encoder);
>         if (ret) {
>                 DRM_DEV_ERROR(dev, "Failed to bind: %d\n", ret);
> -               return ret;
> +               goto out_pm_runtime;
>         }
>
>         return 0;
> +
> +out_pm_runtime:
> +       pm_runtime_put(dsi->dev);
> +       if (dsi->slave)
> +               pm_runtime_put(dsi->slave->dev);
> +
> +       return ret;
>  }
>
>  static void dw_mipi_dsi_rockchip_unbind(struct device *dev,
> @@ -989,6 +986,10 @@ static void dw_mipi_dsi_rockchip_unbind(struct device *dev,
>         dw_mipi_dsi_unbind(dsi->dmd);
>
>         clk_disable_unprepare(dsi->pllref_clk);
> +
> +       pm_runtime_put(dsi->dev);
> +       if (dsi->slave)
> +               pm_runtime_put(dsi->slave->dev);
>  }
>
>  static const struct component_ops dw_mipi_dsi_rockchip_ops = {
> --
> 2.33.0.685.g46640cef36-goog
>