[Intel-gfx] [PATCH v5 21/35] drm/i915: Added a module parameter to allow the scheduler to be disabled

[Jesse Barnes]

On 02/18/2016 06:27 AM, John.C.Harrison at Intel.com wrote:
> From: John Harrison <John.C.Harrison at Intel.com>
> 
> It can be useful to be able to disable the GPU scheduler via a module
> parameter for debugging purposes.
> 
> v5: Converted from a multi-feature 'overrides' mask to a single
> 'enable' boolean. Further features (e.g. pre-emption) will now be
> separate 'enable' booleans added later. [Chris Wilson]
> 
> For: VIZ-1587
> Signed-off-by: John Harrison <John.C.Harrison at Intel.com>
> ---
>  drivers/gpu/drm/i915/i915_params.c    | 4 ++++
>  drivers/gpu/drm/i915/i915_params.h    | 1 +
>  drivers/gpu/drm/i915/i915_scheduler.c | 5 ++++-
>  3 files changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_params.c b/drivers/gpu/drm/i915/i915_params.c
> index d0eba58..0ef3159 100644
> --- a/drivers/gpu/drm/i915/i915_params.c
> +++ b/drivers/gpu/drm/i915/i915_params.c
> @@ -57,6 +57,7 @@ struct i915_params i915 __read_mostly = {
>  	.edp_vswing = 0,
>  	.enable_guc_submission = true,
>  	.guc_log_level = -1,
> +	.enable_scheduler = 0,
>  };
>  
>  module_param_named(modeset, i915.modeset, int, 0400);
> @@ -203,3 +204,6 @@ MODULE_PARM_DESC(enable_guc_submission, "Enable GuC submission (default:false)")
>  module_param_named(guc_log_level, i915.guc_log_level, int, 0400);
>  MODULE_PARM_DESC(guc_log_level,
>  	"GuC firmware logging level (-1:disabled (default), 0-3:enabled)");
> +
> +module_param_named_unsafe(enable_scheduler, i915.enable_scheduler, int, 0600);
> +MODULE_PARM_DESC(enable_scheduler, "Enable scheduler (0 = disable [default], 1 = enable)");
> diff --git a/drivers/gpu/drm/i915/i915_params.h b/drivers/gpu/drm/i915/i915_params.h
> index 5299290..f855c86 100644
> --- a/drivers/gpu/drm/i915/i915_params.h
> +++ b/drivers/gpu/drm/i915/i915_params.h
> @@ -60,6 +60,7 @@ struct i915_params {
>  	bool enable_guc_submission;
>  	bool verbose_state_checks;
>  	bool nuclear_pageflip;
> +	int enable_scheduler;
>  };
>  
>  extern struct i915_params i915 __read_mostly;
> diff --git a/drivers/gpu/drm/i915/i915_scheduler.c b/drivers/gpu/drm/i915/i915_scheduler.c
> index 4f25bf2..47d7de4 100644
> --- a/drivers/gpu/drm/i915/i915_scheduler.c
> +++ b/drivers/gpu/drm/i915/i915_scheduler.c
> @@ -34,6 +34,9 @@ bool i915_scheduler_is_enabled(struct drm_device *dev)
>  {
>  	struct drm_i915_private *dev_priv = dev->dev_private;
>  
> +	if (!i915.enable_scheduler)
> +		return false;
> +
>  	return dev_priv->scheduler != NULL;
>  }
>  
> @@ -548,7 +551,7 @@ int i915_scheduler_queue_execbuffer(struct i915_scheduler_queue_entry *qe)
>  
>  	WARN_ON(!scheduler);
>  
> -	if (1/*!i915.enable_scheduler*/)
> +	if (!i915.enable_scheduler)
>  		return i915_scheduler_queue_execbuffer_bypass(qe);
>  
>  	node = kmalloc(sizeof(*node), GFP_KERNEL);
> 

I did a double take here; maybe a comment along the lines of "if the scheduler is disabled, queue the buffer immediately" would help, and something similar for where the if (1) is added temporarily.

Doesn't matter too much though.

Reviewed-by: Jesse Barnes <jbarnes at virtuousgeek.org>

Thanks,
Jesse