[Intel-gfx] [PATCH] drm/i914/guc: Fix resume on platforms w/o GuC submission but enabled

[Daniele Ceraolo Spurio]

On 10/24/19 9:29 AM, don.hiatt at intel.com wrote:
> From: Don Hiatt <don.hiatt at intel.com>
> 
> Check to see if GuC submission is enabled before requesting the
> EXIT_S_STATE action.
> 

You're only skipping the resume, but does it make any sense to do the 
suspend action if we're not going to call the resume one? Does guc do 
anything in the suspend action that we still require? I thought it only 
saved the submission status, which we don't care about if guc submission 
is disabled.

Daniele

> On some platforms (e.g. KBL) that do not support GuC submission, but
> the user enabled the GuC communication (e.g for HuC authentication)
> calling the GuC EXIT_S_STATE action results in lose of ability to
> enter RC6. Guard against this by only requesting the GuC action on
> platforms that support GuC submission.
> 
> I've verfied that intel_guc_resume() only gets called when driver
> is loaded with: guc_enable={1,2,3}, all other cases (no args,
> guc_enable={0,-1} the intel_guc_resume() is not called.
> 
> Signed-off-by: Don Hiatt <don.hiatt at intel.com>
> ---
>   drivers/gpu/drm/i915/gt/uc/intel_guc.c | 5 ++++-
>   1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc.c b/drivers/gpu/drm/i915/gt/uc/intel_guc.c
> index 37f7bcbf7dac..33318ed135c0 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc.c
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc.c
> @@ -565,7 +565,10 @@ int intel_guc_resume(struct intel_guc *guc)
>   		GUC_POWER_D0,
>   	};
>   
> -	return intel_guc_send(guc, action, ARRAY_SIZE(action));
> +	if (guc->submission_supported)
> +		return intel_guc_send(guc, action, ARRAY_SIZE(action));
> +
> +	return 0;
>   }
>   
>   /**
>