[Intel-gfx] FAILED: patch "[PATCH] drm/i915: Avoid GPU hang when coming out of s3 or s4" failed to apply to 4.0-stable tree

[Jani Nikula]

+intel-gfx, anyone up for a backport?

BR,
Jani.

On Wed, 03 Jun 2015, gregkh at linuxfoundation.org wrote:
> The patch below does not apply to the 4.0-stable tree.
> If someone wants it applied there, or to any other stable or longterm
> tree, then please email the backport, including the original git commit
> id to <stable at vger.kernel.org>.
>
> thanks,
>
> greg k-h
>
> ------------------ original commit in Linus's tree ------------------
>
> From 364aece01a2dd748fc36a1e8bf52ef639b0857bd Mon Sep 17 00:00:00 2001
> From: Peter Antoine <peter.antoine at intel.com>
> Date: Mon, 11 May 2015 08:50:45 +0100
> Subject: [PATCH] drm/i915: Avoid GPU hang when coming out of s3 or s4
>
> This patch fixes a timing issue that causes a GPU hang when the system
> comes out of power saving.
>
> During pm_resume, We are submitting batchbuffers before enabling
> Interrupts this is causing us to miss the context switch interrupt,
> and in consequence intel_execlists_handle_ctx_events is not triggered.
>
> This patch is based on a patch from Deepak S <deepak.s at intel.com>
> from another platform.
>
> The patch fixes an issue introduced by:
>   commit e7778be1eab918274f79603d7c17b3ec8be77386
>   drm/i915: Fix startup failure in LRC mode after recent init changes
>
> The above patch added a call to init_context() to fix an issue introduced
> by a previous patch. But, it then opened up a small timing window for the
> batches being added by the init_context (basically setting up the context)
> to complete before the interrupts have been turned on, thus hanging the
> GPU.
>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=89600
> Cc: stable at vger.kernel.org # 4.0+
> Signed-off-by: Peter Antoine <peter.antoine at intel.com>
> Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>
> [Jani: fixed typo in subject, massaged the comments a bit]
> Signed-off-by: Jani Nikula <jani.nikula at intel.com>
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
> index c302ffb5a168..a19d2c71e205 100644
> --- a/drivers/gpu/drm/i915/i915_drv.c
> +++ b/drivers/gpu/drm/i915/i915_drv.c
> @@ -699,6 +699,16 @@ static int i915_drm_resume(struct drm_device *dev)
>  	intel_init_pch_refclk(dev);
>  	drm_mode_config_reset(dev);
>  
> +	/*
> +	 * Interrupts have to be enabled before any batches are run. If not the
> +	 * GPU will hang. i915_gem_init_hw() will initiate batches to
> +	 * update/restore the context.
> +	 *
> +	 * Modeset enabling in intel_modeset_init_hw() also needs working
> +	 * interrupts.
> +	 */
> +	intel_runtime_pm_enable_interrupts(dev_priv);
> +
>  	mutex_lock(&dev->struct_mutex);
>  	if (i915_gem_init_hw(dev)) {
>  		DRM_ERROR("failed to re-initialize GPU, declaring wedged!\n");
> @@ -706,9 +716,6 @@ static int i915_drm_resume(struct drm_device *dev)
>  	}
>  	mutex_unlock(&dev->struct_mutex);
>  
> -	/* We need working interrupts for modeset enabling ... */
> -	intel_runtime_pm_enable_interrupts(dev_priv);
> -
>  	intel_modeset_init_hw(dev);
>  
>  	spin_lock_irq(&dev_priv->irq_lock);
>

-- 
Jani Nikula, Intel Open Source Technology Center