[Intel-gfx] [PATCH 2/2] drm/i915: Sanitize enable_guc properly on non-guc platforms

[Michal Wajdeczko]

On Tue, 17 Jul 2018 14:53:20 +0200, Ville Syrjala  
<ville.syrjala at linux.intel.com> wrote:

> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
>
> If there's no guc don't try to initialize it even if the user asked for
> it.
>
> Cc: Michal Wajdeczko <michal.wajdeczko at intel.com>
> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> ---
>  drivers/gpu/drm/i915/intel_uc.c | 5 +++++
>  1 file changed, 5 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/intel_uc.c  
> b/drivers/gpu/drm/i915/intel_uc.c
> index 7c95697e1a35..2765808b01e0 100644
> --- a/drivers/gpu/drm/i915/intel_uc.c
> +++ b/drivers/gpu/drm/i915/intel_uc.c
> @@ -106,6 +106,11 @@ static void sanitize_options_early(struct  
> drm_i915_private *i915)
>  	struct intel_uc_fw *guc_fw = &i915->guc.fw;
>  	struct intel_uc_fw *huc_fw = &i915->huc.fw;
> +	if (!HAS_GUC(i915)) {
> +		i915_modparams.enable_guc = 0;
> +		return;
> +	}
> +

This will silently switch from user requested GuC-submission to
execlist-mode which we wanted to stop.

If user don't know what is available on given platform then auto(-1)
mode should be used instead. If user has decided to explicitly specify
invalid enable_guc !0 mode on non-GuC platform why do we want to ignore
that and continue as nothing happened?

Michal

ps. what is your expectation if there is GuC HW but no FW was defined?

>  	/* A negative value means "use platform default" */
>  	if (i915_modparams.enable_guc < 0)
>  		i915_modparams.enable_guc = __get_platform_enable_guc(i915);