Re: [PATCH v2] drm/i915/guc: Allow preempt-client to be NULL

[Mika Kuoppala <mika.kuoppala@linux.intel.com>]

Chris Wilson <chris@chris-wilson.co.uk> writes:

> In the next patch, we may only conditionally allocate the preempt-client
> if there is a global preempt context and so we need to be prepared in
> case the preempt-client itself is NULL.
>
> v2: Grep for more preempt_client.
>
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Michal Winiarski <michal.winiarski@intel.com>
> Cc: Arkadiusz Hiler <arkadiusz.hiler@intel.com>
> Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
> Cc: Michel Thierry <michel.thierry@intel.com>
> Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>

Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>

> ---
>  drivers/gpu/drm/i915/i915_debugfs.c         |  8 +++++---
>  drivers/gpu/drm/i915/intel_guc_submission.c | 27 +++++++++++++++++----------
>  drivers/gpu/drm/i915/selftests/intel_guc.c  | 20 +++++++++++---------
>  3 files changed, 33 insertions(+), 22 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
> index 3849ded354e3..9e44adef30f0 100644
> --- a/drivers/gpu/drm/i915/i915_debugfs.c
> +++ b/drivers/gpu/drm/i915/i915_debugfs.c
> @@ -2338,7 +2338,6 @@ static int i915_guc_info(struct seq_file *m, void *data)
>  		return -ENODEV;
>  
>  	GEM_BUG_ON(!guc->execbuf_client);
> -	GEM_BUG_ON(!guc->preempt_client);
>  
>  	seq_printf(m, "Doorbell map:\n");
>  	seq_printf(m, "\t%*pb\n", GUC_NUM_DOORBELLS, guc->doorbell_bitmap);
> @@ -2346,8 +2345,11 @@ static int i915_guc_info(struct seq_file *m, void *data)
>  
>  	seq_printf(m, "\nGuC execbuf client @ %p:\n", guc->execbuf_client);
>  	i915_guc_client_info(m, dev_priv, guc->execbuf_client);
> -	seq_printf(m, "\nGuC preempt client @ %p:\n", guc->preempt_client);
> -	i915_guc_client_info(m, dev_priv, guc->preempt_client);
> +	if (guc->preempt_client) {
> +		seq_printf(m, "\nGuC preempt client @ %p:\n",
> +			   guc->preempt_client);
> +		i915_guc_client_info(m, dev_priv, guc->preempt_client);
> +	}
>  
>  	i915_guc_log_info(m, dev_priv);
>  
> diff --git a/drivers/gpu/drm/i915/intel_guc_submission.c b/drivers/gpu/drm/i915/intel_guc_submission.c
> index 1f3a8786bbdc..4ea65df05e02 100644
> --- a/drivers/gpu/drm/i915/intel_guc_submission.c
> +++ b/drivers/gpu/drm/i915/intel_guc_submission.c
> @@ -832,10 +832,12 @@ static int guc_clients_doorbell_init(struct intel_guc *guc)
>  	if (ret)
>  		return ret;
>  
> -	ret = create_doorbell(guc->preempt_client);
> -	if (ret) {
> -		destroy_doorbell(guc->execbuf_client);
> -		return ret;
> +	if (guc->preempt_client) {
> +		ret = create_doorbell(guc->preempt_client);
> +		if (ret) {
> +			destroy_doorbell(guc->execbuf_client);
> +			return ret;
> +		}
>  	}
>  
>  	return 0;
> @@ -848,8 +850,11 @@ static void guc_clients_doorbell_fini(struct intel_guc *guc)
>  	 * Instead of trying (in vain) to communicate with it, let's just
>  	 * cleanup the doorbell HW and our internal state.
>  	 */
> -	__destroy_doorbell(guc->preempt_client);
> -	__update_doorbell_desc(guc->preempt_client, GUC_DOORBELL_INVALID);
> +	if (guc->preempt_client) {
> +		__destroy_doorbell(guc->preempt_client);
> +		__update_doorbell_desc(guc->preempt_client,
> +				       GUC_DOORBELL_INVALID);
> +	}
>  	__destroy_doorbell(guc->execbuf_client);
>  	__update_doorbell_desc(guc->execbuf_client, GUC_DOORBELL_INVALID);
>  }
> @@ -998,10 +1003,11 @@ static void guc_clients_destroy(struct intel_guc *guc)
>  {
>  	struct intel_guc_client *client;
>  
> -	client = fetch_and_zero(&guc->execbuf_client);
> -	guc_client_free(client);
> -
>  	client = fetch_and_zero(&guc->preempt_client);
> +	if (client)
> +		guc_client_free(client);
> +
> +	client = fetch_and_zero(&guc->execbuf_client);
>  	guc_client_free(client);
>  }
>  
> @@ -1160,7 +1166,8 @@ int intel_guc_submission_enable(struct intel_guc *guc)
>  	GEM_BUG_ON(!guc->execbuf_client);
>  
>  	guc_reset_wq(guc->execbuf_client);
> -	guc_reset_wq(guc->preempt_client);
> +	if (guc->preempt_client)
> +		guc_reset_wq(guc->preempt_client);
>  
>  	err = intel_guc_sample_forcewake(guc);
>  	if (err)
> diff --git a/drivers/gpu/drm/i915/selftests/intel_guc.c b/drivers/gpu/drm/i915/selftests/intel_guc.c
> index 3f9016466dea..fb74e2cf8a0a 100644
> --- a/drivers/gpu/drm/i915/selftests/intel_guc.c
> +++ b/drivers/gpu/drm/i915/selftests/intel_guc.c
> @@ -87,7 +87,7 @@ static int validate_client(struct intel_guc_client *client,
>  
>  static bool client_doorbell_in_sync(struct intel_guc_client *client)
>  {
> -	return doorbell_ok(client->guc, client->doorbell_id);
> +	return !client || doorbell_ok(client->guc, client->doorbell_id);
>  }
>  
>  /*
> @@ -137,7 +137,6 @@ static int igt_guc_clients(void *args)
>  		goto unlock;
>  	}
>  	GEM_BUG_ON(!guc->execbuf_client);
> -	GEM_BUG_ON(!guc->preempt_client);
>  
>  	err = validate_client(guc->execbuf_client,
>  			      GUC_CLIENT_PRIORITY_KMD_NORMAL, false);
> @@ -146,16 +145,18 @@ static int igt_guc_clients(void *args)
>  		goto out;
>  	}
>  
> -	err = validate_client(guc->preempt_client,
> -			      GUC_CLIENT_PRIORITY_KMD_HIGH, true);
> -	if (err) {
> -		pr_err("preempt client validation failed\n");
> -		goto out;
> +	if (guc->preempt_client) {
> +		err = validate_client(guc->preempt_client,
> +				      GUC_CLIENT_PRIORITY_KMD_HIGH, true);
> +		if (err) {
> +			pr_err("preempt client validation failed\n");
> +			goto out;
> +		}
>  	}
>  
>  	/* each client should now have reserved a doorbell */
>  	if (!has_doorbell(guc->execbuf_client) ||
> -	    !has_doorbell(guc->preempt_client)) {
> +	    (guc->preempt_client && !has_doorbell(guc->preempt_client))) {
>  		pr_err("guc_clients_create didn't reserve doorbells\n");
>  		err = -EINVAL;
>  		goto out;
> @@ -224,7 +225,8 @@ static int igt_guc_clients(void *args)
>  	 * clients during unload.
>  	 */
>  	destroy_doorbell(guc->execbuf_client);
> -	destroy_doorbell(guc->preempt_client);
> +	if (guc->preempt_client)
> +		destroy_doorbell(guc->preempt_client);
>  	guc_clients_destroy(guc);
>  	guc_clients_create(guc);
>  	guc_clients_doorbell_init(guc);
> -- 
> 2.15.1
>
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