Re: [PATCH 04/12] drm/i915: Disable intel HPD poll after DRM poll init/enable

["Hogander, Jouni" <jouni.hogander@intel.com>]

On Thu, 2024-01-04 at 10:30 +0200, Imre Deak wrote:
> The only purpose of intel_hpd_poll_disable() during driver loading
> and
> system resume - at which point polling should be disabled anyway,
> except
> for connectors in an IRQ storm, for which the polling will stay
> enabled -
> is to force-detect all the connectors. However this detection in
> i915_hpd_poll_init_work() depends on drm.mode_config.poll_enabled,
> which
> will get set in drm_kms_helper_poll_init(), possibly after
> i915_hpd_poll_init_work() is scheduled. Hence the initial detection
> of
> connectors during driver loading may not happen.
> 
> Fix the above by moving intel_hpd_poll_disable() after
> i915_hpd_poll_init_work(), the proper place anyway for doing the
> above
> detection after all the HW initialization steps are complete. Change
> the
> order the same way during system resume as well. The above race
> condition shouldn't matter here - as drm.mode_config.poll_enabled
> will
> be set - but the detection should happen here as well after the HW
> init
> steps are done.
> 
> Signed-off-by: Imre Deak <imre.deak@intel.com>

Reviewed-by: Jouni Högander <jouni.hogander@intel.com>

> ---
>  drivers/gpu/drm/i915/display/intel_display_driver.c | 2 +-
>  drivers/gpu/drm/i915/i915_driver.c                  | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_display_driver.c
> b/drivers/gpu/drm/i915/display/intel_display_driver.c
> index da549962feccd..1974f2394a518 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_driver.c
> +++ b/drivers/gpu/drm/i915/display/intel_display_driver.c
> @@ -374,7 +374,6 @@ int intel_display_driver_probe(struct
> drm_i915_private *i915)
>  
>         /* Only enable hotplug handling once the fbdev is fully set
> up. */
>         intel_hpd_init(i915);
> -       intel_hpd_poll_disable(i915);
>  
>         skl_watermark_ipc_init(i915);
>  
> @@ -412,6 +411,7 @@ void intel_display_driver_register(struct
> drm_i915_private *i915)
>          * fbdev->async_cookie.
>          */
>         drm_kms_helper_poll_init(&i915->drm);
> +       intel_hpd_poll_disable(i915);
>  
>         intel_display_device_info_print(DISPLAY_INFO(i915),
>                                         DISPLAY_RUNTIME_INFO(i915),
> &p);
> diff --git a/drivers/gpu/drm/i915/i915_driver.c
> b/drivers/gpu/drm/i915/i915_driver.c
> index c7d7c3b7ecc63..be86596a8904d 100644
> --- a/drivers/gpu/drm/i915/i915_driver.c
> +++ b/drivers/gpu/drm/i915/i915_driver.c
> @@ -1249,9 +1249,9 @@ static int i915_drm_resume(struct drm_device
> *dev)
>         intel_dp_mst_resume(dev_priv);
>         intel_display_driver_resume(dev_priv);
>  
> -       intel_hpd_poll_disable(dev_priv);
>         if (HAS_DISPLAY(dev_priv))
>                 drm_kms_helper_poll_enable(dev);
> +       intel_hpd_poll_disable(dev_priv);
>  
>         intel_opregion_resume(dev_priv);
>