On Wed, Sep 29, 2021 at 02:41:03PM -0700, Brian Norris wrote:
> If the display is not enable()d, then we aren't holding a runtime PM
> reference here. Thus, it's easy to accidentally cause a hang, if user
> space is poking around at /dev/drm_dp_aux0 at the "wrong" time.
>
> Let's get the panel and PM state right before trying to talk AUX.
>
> Fixes: 0d97ad03f422 ("drm/bridge: analogix_dp: Remove duplicated code")
> Cc: <stable@xxxxxxxxxxxxxxx>
> Cc: Tomeu Vizoso <tomeu.vizoso@xxxxxxxxxxxxx>
> Signed-off-by: Brian Norris <briannorris@xxxxxxxxxxxx>
> ---
>
> .../gpu/drm/bridge/analogix/analogix_dp_core.c | 17 ++++++++++++++++-
> 1 file changed, 16 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
> index b7d2e4449cfa..a1b553904b85 100644
> --- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
> +++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
> @@ -1632,8 +1632,23 @@ static ssize_t analogix_dpaux_transfer(struct drm_dp_aux *aux,
> struct drm_dp_aux_msg *msg)
> {
> struct analogix_dp_device *dp = to_dp(aux);
> + int ret, ret2;
>
> - return analogix_dp_transfer(dp, msg);
> + ret = analogix_dp_prepare_panel(dp, true, false);
> + if (ret) {
> + DRM_DEV_ERROR(dp->dev, "Failed to prepare panel (%d)\n", ret);
s/DRM_DEV_ERROR/drm_err/
> + return ret;
> + }
> +
> + pm_runtime_get_sync(dp->dev);
> + ret = analogix_dp_transfer(dp, msg);
> + pm_runtime_put(dp->dev);
> +
> + ret2 = analogix_dp_prepare_panel(dp, false, false);
> + if (ret2)
> + DRM_DEV_ERROR(dp->dev, "Failed to unprepare panel (%d)\n", ret2);
What's the reasoning for not propagating unprepare failures? I feel like that
should be fair game.
> +
> + return ret;
> }
>
> struct analogix_dp_device *
> --
> 2.33.0.685.g46640cef36-goog
>
--
Sean Paul, Software Engineer, Google / Chromium OS
