[Intel-gfx] [PATCH] drm/i915: use delayed work for resume hotplug v2

[Chris Wilson]

On Tue, Oct 07, 2014 at 01:25:23PM -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)
> 
> Signed-off-by: Jesse Barnes <jbarnes at virtuousgeek.org>
> ---
>  drivers/gpu/drm/i915/i915_dma.c | 10 ++++++++++
>  drivers/gpu/drm/i915/i915_drv.c |  8 ++++++--
>  drivers/gpu/drm/i915/i915_drv.h |  1 +
>  3 files changed, 17 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
> index 85d14e1..633095d 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
> diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
> index a05a1d0..83075f9 100644
> --- a/drivers/gpu/drm/i915/i915_drv.c
> +++ b/drivers/gpu/drm/i915/i915_drv.c
> @@ -726,8 +726,12 @@ 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. Just
> +		 * try to make sure the rest of driver resume is finished
> +		 * before we start probing for config changes.

This is a nice vague statement that scares me. If half of this comment
is true, using a simple delay is periliously lackadaisical. The commit
log just talks about speeding up resume, but this comment implies to me
something more sinister.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre