Re: [Intel-gfx] [PATCH v2] drm/i915/irq: Clear GFX_MSTR_IRQ as part of IRQ reset

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Wed, Sep 20, 2023 at 04:53:52PM -0300, Gustavo Sousa wrote:
> Starting with Xe_LP+, GFX_MSTR_IRQ contains status bits that have W1C
> behavior. If we do not properly reset them, we would miss delivery of
> interrupts if a pending bit is set when enabling IRQs.
> 
> As an example, the display part of our probe routine contains paths
> where we wait for vblank interrupts. If a display interrupt was already
> pending when enabling IRQs, we would time out waiting for the vblank.
> 
> Avoid the potential issue by clearing GFX_MSTR_IRQ as part of the IRQ
> reset.
> 
> v2:
>   - Move logic from gen11_gt_irq_reset() to dg1_irq_reset(). (Matt)
> 
> BSpec: 50875, 54028
> Cc: Matt Roper <matthew.d.roper@intel.com>
> Signed-off-by: Gustavo Sousa <gustavo.sousa@intel.com>
> ---
>  drivers/gpu/drm/i915/i915_irq.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
> index 1bfcfbe6e30b..8130f043693b 100644
> --- a/drivers/gpu/drm/i915/i915_irq.c
> +++ b/drivers/gpu/drm/i915/i915_irq.c
> @@ -751,6 +751,8 @@ static void dg1_irq_reset(struct drm_i915_private *dev_priv)
>  
>  	GEN3_IRQ_RESET(uncore, GEN11_GU_MISC_);
>  	GEN3_IRQ_RESET(uncore, GEN8_PCU_);
> +
> +	intel_uncore_write(uncore, GEN11_GFX_MSTR_IRQ, ~0);

Did you confirm that it's not double buffered?

>  }
>  
>  static void cherryview_irq_reset(struct drm_i915_private *dev_priv)
> -- 
> 2.42.0

-- 
Ville Syrjälä
Intel