[Intel-gfx] [PATCH 4/7] drm/i915/uc: Stop talking with GuC when resetting

[Chris Wilson]

Quoting Michal Wajdeczko (2019-05-17 17:22:24)
> Knowing that GuC will be reset soon, we may stop all communication
> immediately without doing graceful cleanup as it is not needed.
> 
> Signed-off-by: Michal Wajdeczko <michal.wajdeczko at intel.com>
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio at intel.com>
> ---
>  drivers/gpu/drm/i915/intel_guc_ct.h |  5 +++++
>  drivers/gpu/drm/i915/intel_uc.c     | 13 ++++++++++++-
>  2 files changed, 17 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_guc_ct.h b/drivers/gpu/drm/i915/intel_guc_ct.h
> index f5e7f0663304..41ba593a4df7 100644
> --- a/drivers/gpu/drm/i915/intel_guc_ct.h
> +++ b/drivers/gpu/drm/i915/intel_guc_ct.h
> @@ -96,4 +96,9 @@ void intel_guc_ct_fini(struct intel_guc_ct *ct);
>  int intel_guc_ct_enable(struct intel_guc_ct *ct);
>  void intel_guc_ct_disable(struct intel_guc_ct *ct);
>  
> +static inline void intel_guc_ct_stop(struct intel_guc_ct *ct)
> +{
> +       ct->host_channel.enabled = false;
> +}
> +
>  #endif /* _INTEL_GUC_CT_H_ */
> diff --git a/drivers/gpu/drm/i915/intel_uc.c b/drivers/gpu/drm/i915/intel_uc.c
> index 9d86cd831ea7..86edfa5ad72e 100644
> --- a/drivers/gpu/drm/i915/intel_uc.c
> +++ b/drivers/gpu/drm/i915/intel_uc.c
> @@ -224,6 +224,17 @@ static int guc_enable_communication(struct intel_guc *guc)
>         return 0;
>  }
>  
> +static void guc_stop_communication(struct intel_guc *guc)
> +{
> +       struct drm_i915_private *i915 = guc_to_i915(guc);
> +
> +       if (HAS_GUC_CT(i915))

Does this not fall out of some local knowledge? Though for the moment it
is harmless to stop a non-existent intel_guc_ct.

> +               intel_guc_ct_stop(&guc->ct);

Any serialisation required here? Or caveats for callers to observe?

> +       guc->send = intel_guc_send_nop;
> +       guc->handler = intel_guc_to_host_event_handler_nop;
> +}