Re: [PATCH 2/5] drm/i915/irq: use a dedicated IMR cache for gen 5-7

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

On Thu, Sep 18, 2025 at 03:25:45PM +0300, Jani Nikula wrote:
> There are three groups of platforms using i915->irq_mask independently:
> gen 2-4, VLV/CHV, and gen 5-7.
> 
> The gen 5-7 usage is primarily limited to display. Move its irq_mask
> usage to struct intel_display as ilk_de_imr_mask for gen 5-7.
> 
> ilk_de_imr_mask could be put inside a union with with vlv_imr_mask and
> de_irq_mask[], but keep them separate to avoid accidental aliasing of
> the values.
> 
> With this, we can also drop the irq_mask member from struct xe_device.
> 
> Signed-off-by: Jani Nikula <jani.nikula@intel.com>

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

> ---
>  drivers/gpu/drm/i915/display/intel_display_core.h |  5 +++++
>  drivers/gpu/drm/i915/display/intel_display_irq.c  | 14 ++++++--------
>  drivers/gpu/drm/i915/i915_irq.c                   |  2 +-
>  drivers/gpu/drm/xe/xe_device_types.h              |  3 ---
>  4 files changed, 12 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_display_core.h b/drivers/gpu/drm/i915/display/intel_display_core.h
> index 48a707557c29..4a52bbe327b7 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_core.h
> +++ b/drivers/gpu/drm/i915/display/intel_display_core.h
> @@ -480,6 +480,11 @@ struct intel_display {
>  		 * bitfield.
>  		 */
>  		u32 vlv_imr_mask;
> +		/*
> +		 * Cached value of gen 5-7 DE IMR to avoid reads in updating the
> +		 * bitfield.
> +		 */
> +		u32 ilk_de_imr_mask;
>  		u32 de_irq_mask[I915_MAX_PIPES];
>  		u32 pipestat_irq_mask[I915_MAX_PIPES];
>  	} irq;
> diff --git a/drivers/gpu/drm/i915/display/intel_display_irq.c b/drivers/gpu/drm/i915/display/intel_display_irq.c
> index df718670546b..f4ba9b08e044 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_irq.c
> +++ b/drivers/gpu/drm/i915/display/intel_display_irq.c
> @@ -140,14 +140,14 @@ void ilk_update_display_irq(struct intel_display *display,
>  	lockdep_assert_held(&display->irq.lock);
>  	drm_WARN_ON(display->drm, enabled_irq_mask & ~interrupt_mask);
>  
> -	new_val = dev_priv->irq_mask;
> +	new_val = display->irq.ilk_de_imr_mask;
>  	new_val &= ~interrupt_mask;
>  	new_val |= (~enabled_irq_mask & interrupt_mask);
>  
> -	if (new_val != dev_priv->irq_mask &&
> +	if (new_val != display->irq.ilk_de_imr_mask &&
>  	    !drm_WARN_ON(display->drm, !intel_irqs_enabled(dev_priv))) {
> -		dev_priv->irq_mask = new_val;
> -		intel_de_write(display, DEIMR, dev_priv->irq_mask);
> +		display->irq.ilk_de_imr_mask = new_val;
> +		intel_de_write(display, DEIMR, display->irq.ilk_de_imr_mask);
>  		intel_de_posting_read(display, DEIMR);
>  	}
>  }
> @@ -2180,8 +2180,6 @@ void valleyview_disable_display_irqs(struct intel_display *display)
>  
>  void ilk_de_irq_postinstall(struct intel_display *display)
>  {
> -	struct drm_i915_private *i915 = to_i915(display->drm);
> -
>  	u32 display_mask, extra_mask;
>  
>  	if (DISPLAY_VER(display) >= 7) {
> @@ -2213,11 +2211,11 @@ void ilk_de_irq_postinstall(struct intel_display *display)
>  	if (display->platform.ironlake && display->platform.mobile)
>  		extra_mask |= DE_PCU_EVENT;
>  
> -	i915->irq_mask = ~display_mask;
> +	display->irq.ilk_de_imr_mask = ~display_mask;
>  
>  	ibx_irq_postinstall(display);
>  
> -	intel_display_irq_regs_init(display, DE_IRQ_REGS, i915->irq_mask,
> +	intel_display_irq_regs_init(display, DE_IRQ_REGS, display->irq.ilk_de_imr_mask,
>  				    display_mask | extra_mask);
>  }
>  
> diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
> index 8d5da222a187..e5fdfd51b549 100644
> --- a/drivers/gpu/drm/i915/i915_irq.c
> +++ b/drivers/gpu/drm/i915/i915_irq.c
> @@ -659,7 +659,7 @@ static void ilk_irq_reset(struct drm_i915_private *dev_priv)
>  	struct intel_uncore *uncore = &dev_priv->uncore;
>  
>  	gen2_irq_reset(uncore, DE_IRQ_REGS);
> -	dev_priv->irq_mask = ~0u;
> +	display->irq.ilk_de_imr_mask = ~0u;
>  
>  	if (GRAPHICS_VER(dev_priv) == 7)
>  		intel_uncore_write(uncore, GEN7_ERR_INT, 0xffffffff);
> diff --git a/drivers/gpu/drm/xe/xe_device_types.h b/drivers/gpu/drm/xe/xe_device_types.h
> index a05b453245cc..6cf2466348b4 100644
> --- a/drivers/gpu/drm/xe/xe_device_types.h
> +++ b/drivers/gpu/drm/xe/xe_device_types.h
> @@ -624,9 +624,6 @@ struct xe_device {
>  	/* To shut up runtime pm macros.. */
>  	struct xe_runtime_pm {} runtime_pm;
>  
> -	/* only to allow build, not used functionally */
> -	u32 irq_mask;
> -
>  	struct intel_uncore {
>  		spinlock_t lock;
>  	} uncore;
> -- 
> 2.47.3

-- 
Ville Syrjälä
Intel