[Intel-gfx] [PATCH] drm/i915: Only allocate preempt context when required

[Daniele Ceraolo Spurio]

<snip>

> @@ -979,17 +979,19 @@ static int guc_clients_create(struct intel_guc *guc)
>   	}
>   	guc->execbuf_client = client;
>   
> -	client = guc_client_alloc(dev_priv,
> -				  INTEL_INFO(dev_priv)->ring_mask,
> -				  GUC_CLIENT_PRIORITY_KMD_HIGH,
> -				  dev_priv->preempt_context);
> -	if (IS_ERR(client)) {
> -		DRM_ERROR("Failed to create GuC client for preemption!\n");
> -		guc_client_free(guc->execbuf_client);
> -		guc->execbuf_client = NULL;
> -		return PTR_ERR(client);
> +	if (dev_priv->preempt_context) {
> +		client = guc_client_alloc(dev_priv,
> +					  INTEL_INFO(dev_priv)->ring_mask,
> +					  GUC_CLIENT_PRIORITY_KMD_HIGH,
> +					  dev_priv->preempt_context);
> +		if (IS_ERR(client)) {
> +			DRM_ERROR("Failed to create GuC client for preemption!\n");
> +			guc_client_free(guc->execbuf_client);
> +			guc->execbuf_client = NULL;
> +			return PTR_ERR(client);
> +		}
> +		guc->preempt_client = client;
>   	}

I was having another look at this patch while rebasing my patches on top 
of it and I noticed that although guc->preempt_client is now not always 
created other code still assumes that it is always there. All platforms 
with GuC also have preemption, so i think the only case in which we can 
have issues is when we fail to create the preempt context and keep going 
with the driver loading assuming preemption disabled.

Daniele