Re: [Intel-gfx] [PATCH 39/47] drm/i915/guc: Don't complain about reset races

[Matthew Brost <matthew.brost@intel.com>]

On Thu, Jun 24, 2021 at 12:05:08AM -0700, Matthew Brost wrote:
> From: John Harrison <John.C.Harrison@Intel.com>
> 
> It is impossible to seal all race conditions of resets occurring
> concurrent to other operations. At least, not without introducing
> excesive mutex locking. Instead, don't complain if it occurs. In
> particular, don't complain if trying to send a H2G during a reset.
> Whatever the H2G was about should get redone once the reset is over.
> 
> Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
> Signed-off-by: Matthew Brost <matthew.brost@intel.com>

Reviewed-by: Matthew Brost <matthew.brost@intel.com>

> ---
>  drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c | 5 ++++-
>  drivers/gpu/drm/i915/gt/uc/intel_uc.c     | 3 +++
>  drivers/gpu/drm/i915/gt/uc/intel_uc.h     | 2 ++
>  3 files changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c
> index dd6177c8d75c..3b32755f892e 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c
> @@ -727,7 +727,10 @@ int intel_guc_ct_send(struct intel_guc_ct *ct, const u32 *action, u32 len,
>  	int ret;
>  
>  	if (unlikely(!ct->enabled)) {
> -		WARN(1, "Unexpected send: action=%#x\n", *action);
> +		struct intel_guc *guc = ct_to_guc(ct);
> +		struct intel_uc *uc = container_of(guc, struct intel_uc, guc);
> +
> +		WARN(!uc->reset_in_progress, "Unexpected send: action=%#x\n", *action);
>  		return -ENODEV;
>  	}
>  
> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_uc.c b/drivers/gpu/drm/i915/gt/uc/intel_uc.c
> index b523a8521351..77c1fe2ed883 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_uc.c
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_uc.c
> @@ -550,6 +550,7 @@ void intel_uc_reset_prepare(struct intel_uc *uc)
>  {
>  	struct intel_guc *guc = &uc->guc;
>  
> +	uc->reset_in_progress = true;
>  
>  	/* Nothing to do if GuC isn't supported */
>  	if (!intel_uc_supports_guc(uc))
> @@ -579,6 +580,8 @@ void intel_uc_reset_finish(struct intel_uc *uc)
>  {
>  	struct intel_guc *guc = &uc->guc;
>  
> +	uc->reset_in_progress = false;
> +
>  	/* Firmware expected to be running when this function is called */
>  	if (intel_guc_is_fw_running(guc) && intel_uc_uses_guc_submission(uc))
>  		intel_guc_submission_reset_finish(guc);
> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_uc.h b/drivers/gpu/drm/i915/gt/uc/intel_uc.h
> index eaa3202192ac..91315e3f1c58 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_uc.h
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_uc.h
> @@ -30,6 +30,8 @@ struct intel_uc {
>  
>  	/* Snapshot of GuC log from last failed load */
>  	struct drm_i915_gem_object *load_err_log;
> +
> +	bool reset_in_progress;
>  };
>  
>  void intel_uc_init_early(struct intel_uc *uc);
> -- 
> 2.28.0
> 
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