Re: [PATCH v4 4/9] drm/i915/guc: Update suspend functionality in intel_uc_suspend path

["Michał Winiarski" <michal.winiarski@intel.com>]

On Wed, Sep 20, 2017 at 11:08:19PM +0530, Sagar Arun Kamble wrote:
> With this patch we disable GuC submission in i915_drm_suspend. This will
> destroy the client which will be setup back again. We also reuse the
> complete sanitization done via intel_uc_runtime_suspend in this path.
> Post drm resume this state is recreated by intel_uc_init_hw hence we need
> not have similar reuse for intel_uc_resume.
> This also fixes issue where intel_uc_fini_hw was being called after GPU
> reset happening in i915_gem_suspend in i915_driver_unload.
> 
> v2: Rebase w.r.t removal of GuC code restructuring. Added struct_mutex
> protection for i915_guc_submission_disable.
> 
> Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
> Cc: Michał Winiarski <michal.winiarski@intel.com>
> Signed-off-by: Sagar Arun Kamble <sagar.a.kamble@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_uc.c | 18 ++++++++++++++----
>  1 file changed, 14 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_uc.c b/drivers/gpu/drm/i915/intel_uc.c
> index fa698db..0c7e45c7 100644
> --- a/drivers/gpu/drm/i915/intel_uc.c
> +++ b/drivers/gpu/drm/i915/intel_uc.c
> @@ -446,9 +446,6 @@ void intel_uc_fini_hw(struct drm_i915_private *dev_priv)
>  	if (!i915.enable_guc_loading)
>  		return;
>  
> -	if (i915.enable_guc_submission)
> -		i915_guc_submission_disable(dev_priv);
> -
>  	guc_disable_communication(&dev_priv->guc);
>  
>  	if (i915.enable_guc_submission) {
> @@ -654,7 +651,20 @@ int intel_uc_runtime_resume(struct drm_i915_private *dev_priv)
>  
>  int intel_uc_suspend(struct drm_i915_private *dev_priv)
>  {
> -	return intel_guc_enter_sleep(&dev_priv->guc);
> +	struct drm_device *dev = &dev_priv->drm;
> +	int ret;

Drop the locals.
I'd drop the dev, and just go through dev_priv in this case.

> +
> +	if (i915.enable_guc_submission) {
> +		mutex_lock(&dev->struct_mutex);
> +		i915_guc_submission_disable(dev_priv);
> +		mutex_unlock(&dev->struct_mutex);
> +	}

Since we're starting to use i915_guc_submission_disable from different places,
some of which without struct_mutex already held (like this one), it would be a
good idea to add a lockdep assert documenting this requirement inside both
i915_guc_submission_enable and i915_guc_submission_disable.
It could be even squeezed in with this patch IMHO.

> +
> +	ret = intel_uc_runtime_suspend(dev_priv);
> +	if (ret)
> +		return ret;

return intel_guc_runtime_suspend(dev_priv);

With that:

Reviewed-by: Michał Winiarski <michal.winiarski@intel.com>

-Michał

> +
> +	return 0;
>  }
>  
>  int intel_uc_resume(struct drm_i915_private *dev_priv)
> -- 
> 1.9.1
> 
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