Re: [Intel-gfx] [PATCH v2 3/8] drm/i915: Probe whether SAGV works on pre-icl

["Lisovskiy, Stanislav" <stanislav.lisovskiy@intel.com>]

On Wed, Mar 09, 2022 at 06:49:43PM +0200, Ville Syrjala wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> 
> Instead of leaving the SAGV enable/disable to the first commit
> let's try to disable it first thing to see if we can do it or
> not (disabling SAGV is a safe thing to at any time). This avoids
> running the code in this funny intermediate state where we don't
> know if SAGV is available or not.
> 
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

Reviewed-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>

> ---
>  drivers/gpu/drm/i915/intel_pm.c | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index 906501d6b298..36f5bccabf64 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -57,6 +57,8 @@
>  #include "vlv_sideband.h"
>  #include "../../../platform/x86/intel_ips.h"
>  
> +static int intel_disable_sagv(struct drm_i915_private *dev_priv);
> +
>  struct drm_i915_clock_gating_funcs {
>  	void (*init_clock_gating)(struct drm_i915_private *i915);
>  };
> @@ -3697,6 +3699,18 @@ intel_sagv_block_time(struct drm_i915_private *dev_priv)
>  
>  static void intel_sagv_init(struct drm_i915_private *i915)
>  {
> +	if (!intel_has_sagv(i915))
> +		i915->sagv_status = I915_SAGV_NOT_CONTROLLED;
> +
> +	/*
> +	 * Probe to see if we have working SAGV control.
> +	 * For icl+ this was already determined by intel_bw_init_hw().
> +	 */
> +	if (DISPLAY_VER(i915) < 11)
> +		intel_disable_sagv(i915);
> +
> +	drm_WARN_ON(&i915->drm, i915->sagv_status == I915_SAGV_UNKNOWN);
> +
>  	i915->sagv_block_time_us = intel_sagv_block_time(i915);
>  
>  	drm_dbg_kms(&i915->drm, "SAGV supported: %s, original SAGV block time: %u us\n",
> -- 
> 2.34.1
>