Re: [PATCH] drm/i915: use delayed work for resume hotplug v4

[Daniel Vetter <daniel@ffwll.ch>]

On Thu, Oct 09, 2014 at 08:13:18AM -0700, Jesse Barnes wrote:
> Gets the detect code (which may take awhile) out of the resume path,
> speeding things up a bit.
> 
> v2: use a delayed work queue instead (Daniel)
> v3: cancel delayed work at unload and suspend time (Jesse)
> v4: make delayed work comment less scary (Chris)
> 
> Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

Is this r-b: Chris or not? Two comments below.
-Daniel

> ---
>  drivers/gpu/drm/i915/i915_dma.c | 12 ++++++++++++
>  drivers/gpu/drm/i915/i915_drv.c | 19 +++++++++++++++++--
>  drivers/gpu/drm/i915/i915_drv.h |  1 +
>  3 files changed, 30 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
> index 85d14e1..65001de 100644
> --- a/drivers/gpu/drm/i915/i915_dma.c
> +++ b/drivers/gpu/drm/i915/i915_dma.c
> @@ -1303,6 +1303,15 @@ static const struct vga_switcheroo_client_ops i915_switcheroo_ops = {
>  	.can_switch = i915_switcheroo_can_switch,
>  };
>  
> +static void intel_resume_hotplug(struct work_struct *work)
> +{
> +	struct drm_i915_private *dev_priv =
> +		container_of(work, struct drm_i915_private,
> +			     hotplug_resume_work.work);
> +
> +	drm_helper_hpd_irq_event(dev_priv->dev);
> +}
> +
>  static int i915_load_modeset_init(struct drm_device *dev)
>  {
>  	struct drm_i915_private *dev_priv = dev->dev_private;
> @@ -1364,6 +1373,7 @@ static int i915_load_modeset_init(struct drm_device *dev)
>  
>  	/* Only enable hotplug handling once the fbdev is fully set up. */
>  	intel_hpd_init(dev_priv);
> +	INIT_DELAYED_WORK(&dev_priv->hotplug_resume_work, intel_resume_hotplug);
>  
>  	/*
>  	 * Some ports require correctly set-up hpd registers for detection to
> @@ -1854,6 +1864,8 @@ int i915_driver_unload(struct drm_device *dev)
>  	acpi_video_unregister();
>  
>  	if (drm_core_check_feature(dev, DRIVER_MODESET)) {
> +		cancel_delayed_work(&dev_priv->hotplug_resume_work);
> +

This should be moved to intel_modeset_cleanup to the other hpd quiescent
calls imo. Splattering stuff all over isn't good, and if we need to stop
hpd handling here already then we should move everything.

>  		intel_fbdev_fini(dev);
>  		intel_modeset_cleanup(dev);
>  
> diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
> index a05a1d0..74fc289 100644
> --- a/drivers/gpu/drm/i915/i915_drv.c
> +++ b/drivers/gpu/drm/i915/i915_drv.c
> @@ -585,6 +585,12 @@ static int i915_drm_freeze(struct drm_device *dev)
>  		}
>  
>  		/*
> +		 * In case we haven't run this by the time we resume, we may
> +		 * as well cancel until we resume again.
> +		 */
> +		cancel_delayed_work(&dev_priv->hotplug_resume_work);

Again this should be right next to the other hpd quiescence calls, i.e.
next to drm_kms_helper_poll_disable.

> +
> +		/*
>  		 * Disable CRTCs directly since we want to preserve sw state
>  		 * for _thaw. Also, power gate the CRTC power wells.
>  		 */
> @@ -726,8 +732,17 @@ static int __i915_drm_thaw(struct drm_device *dev, bool restore_gtt_mappings)
>  		 * notifications.
>  		 * */
>  		intel_hpd_init(dev_priv);
> -		/* Config may have changed between suspend and resume */
> -		drm_helper_hpd_irq_event(dev);
> +
> +		/*
> +		 * Config may have changed between suspend and resume, queue
> +		 * a hotplug notification for userspace to check when it wakes
> +		 * up. Delay the work slightly so that the resume has time to
> +		 * finish, before userspace starts pounding at the gates
> +		 * checking for changes. This speeds up the resume process by
> +		 * reducing contention for resources.
> +		 */
> +		schedule_delayed_work(&dev_priv->hotplug_resume_work,
> +				      msecs_to_jiffies(50));
>  	}
>  
>  	intel_opregion_init(dev);
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 1e476b5..6273ad6 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -1521,6 +1521,7 @@ struct drm_i915_private {
>  	} hpd_stats[HPD_NUM_PINS];
>  	u32 hpd_event_bits;
>  	struct delayed_work hotplug_reenable_work;
> +	struct delayed_work hotplug_resume_work;
>  
>  	struct i915_fbc fbc;
>  	struct i915_drrs drrs;
> -- 
> 1.9.1
> 
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch