Re: [PATCH] drm/i915: disable interrupts earlier in the driver unload code

[Jani Nikula <jani.nikula@intel.com>]

On Wed, 24 Apr 2013, Daniel Vetter <daniel.vetter@ffwll.ch> wrote:
> Our rps code relies on the interrupts being off to prevent re-arming
> of the work items at inopportune moments.
>
> Also drop the redundant cancel_work for the main rps work,
> disable_gt_powersave already takes care of that.
>
> Finally add a WARN_ON to ensure we obey that piece of ordering
> constraint. Long term I want to lock down the setup/teardown code in a
> similar way to how we painstakingly check modeset sequence constraints
> already.
>
> v2: Disable polling after hpd handling is shut down - since Egbert's
> hpd irq storm handling the hotplug work can re-arm the polling
> handler. Spotted by Jani Nikula.

Reviewed-by: Jani Nikula <jani.nikula@intel.com>

>
> Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
> Cc: Jani Nikula <jani.nikula@intel.com>
> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> ---
>  drivers/gpu/drm/i915/intel_display.c |   19 ++++++++++++-------
>  drivers/gpu/drm/i915/intel_pm.c      |    3 +++
>  2 files changed, 15 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 74156e2..988e543 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -9530,12 +9530,23 @@ void intel_modeset_cleanup(struct drm_device *dev)
>  	struct drm_crtc *crtc;
>  	struct intel_crtc *intel_crtc;
>  
> +	/*
> +	 * Interrupts and polling as the first thing to avoid creating havoc.
> +	 * Too much stuff here (turning of rps, connectors, ...) would
> +	 * experience fancy races otherwise.
> +	 */
> +	drm_irq_uninstall(dev);
> +	cancel_work_sync(&dev_priv->hotplug_work);
> +	/*
> +	 * Due to the hpd irq storm handling the hotplug work can re-arm the
> +	 * poll handlers. Hence disable polling after hpd handling is shut down.
> +	 */
>  	drm_kms_helper_poll_fini(dev);
> +
>  	mutex_lock(&dev->struct_mutex);
>  
>  	intel_unregister_dsm_handler();
>  
> -
>  	list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
>  		/* Skip inactive CRTCs */
>  		if (!crtc->fb)
> @@ -9553,12 +9564,6 @@ void intel_modeset_cleanup(struct drm_device *dev)
>  
>  	mutex_unlock(&dev->struct_mutex);
>  
> -	/* Disable the irq before mode object teardown, for the irq might
> -	 * enqueue unpin/hotplug work. */
> -	drm_irq_uninstall(dev);
> -	cancel_work_sync(&dev_priv->hotplug_work);
> -	cancel_work_sync(&dev_priv->rps.work);
> -
>  	/* flush any delayed tasks or pending work */
>  	flush_scheduled_work();
>  
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index 8b7f050..bb45122 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -3671,6 +3671,9 @@ void intel_disable_gt_powersave(struct drm_device *dev)
>  {
>  	struct drm_i915_private *dev_priv = dev->dev_private;
>  
> +	/* Interrupts should be disabled already to avoid re-arming. */
> +	WARN_ON(dev->irq_enabled);
> +
>  	if (IS_IRONLAKE_M(dev)) {
>  		ironlake_disable_drps(dev);
>  		ironlake_disable_rc6(dev);
> -- 
> 1.7.10.4