On Wed, Mar 09, 2022 at 06:49:44PM +0200, Ville Syrjala wrote:
> From: Ville Syrjälä
>
> If the mailbox returns an exceesively large SAGV block time let's just
> reject it. This avoids having to worry about overflows when we add the
> SAGV block time to the wm0 latency.
>
> We shall put the limit arbitrarily at U16_MAX. >65msec latency
> doesn't really make sense to me in any case.
>
> Signed-off-by: Ville Syrjälä
Reviewed-by: Stanislav Lisovskiy
> ---
> drivers/gpu/drm/i915/intel_pm.c | 6 ++
> 1 file changed, 6 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index 36f5bccabf64..166246fa27e4 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -3716,6 +3716,12 @@ static void intel_sagv_init(struct drm_i915_private
> *i915)
> drm_dbg_kms(>drm, "SAGV supported: %s, original SAGV block time:
> %u us\n",
> str_yes_no(intel_has_sagv(i915)), i915->sagv_block_time_us);
>
> + /* avoid overflow when adding with wm0 latency/etc. */
> + if (drm_WARN(>drm, i915->sagv_block_time_us > U16_MAX,
> + "Excessive SAGV block time %u, ignoring\n",
> + i915->sagv_block_time_us))
> + i915->sagv_block_time_us = 0;
> +
> if (!intel_has_sagv(i915))
> i915->sagv_block_time_us = 0;
> }
> --
> 2.34.1
>
