Re: [PATCH 1/2] drm/i915/display_wa: Add helpers to check wa

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

On Wed, Jul 02, 2025 at 02:16:18PM +0530, Ankit Nautiyal wrote:
> Introduce a generic helper to check display workarounds using an enum.
> 
> Convert Wa_16023588340 to use the new interface, simplifying WA checks
> and making future additions easier.
> 
> v2: Use drm_WARN instead of MISSING_CASE and simplify intel_display_wa
> macro. (Jani)
> 
> Suggested-by: Jani Nikula <jani.nikula@intel.com>
> Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_display_wa.c | 15 +++++++++++++++
>  drivers/gpu/drm/i915/display/intel_display_wa.h |  9 +++++++++
>  drivers/gpu/drm/i915/display/intel_fbc.c        |  2 +-
>  3 files changed, 25 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_display_wa.c b/drivers/gpu/drm/i915/display/intel_display_wa.c
> index f57280e9d041..f5e8d58d9a68 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_wa.c
> +++ b/drivers/gpu/drm/i915/display/intel_display_wa.c
> @@ -3,6 +3,8 @@
>   * Copyright © 2023 Intel Corporation
>   */
>  
> +#include "drm/drm_print.h"
> +
>  #include "i915_reg.h"
>  #include "intel_de.h"
>  #include "intel_display_core.h"
> @@ -39,3 +41,16 @@ void intel_display_wa_apply(struct intel_display *display)
>  	else if (DISPLAY_VER(display) == 11)
>  		gen11_display_wa_apply(display);
>  }
> +
> +bool __intel_display_wa(struct intel_display *display, enum intel_display_wa wa)
> +{
> +	switch (wa) {
> +	case INTEL_DISPLAY_WA_16023588340:
> +		return intel_display_needs_wa_16023588340(display);
> +	default:
> +		drm_WARN(display->drm, 1, "Missing Wa number: %d\n", wa);
> +		break;
> +	}
> +
> +	return false;
> +}
> diff --git a/drivers/gpu/drm/i915/display/intel_display_wa.h b/drivers/gpu/drm/i915/display/intel_display_wa.h
> index babd9d16603d..146ee70d66f7 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_wa.h
> +++ b/drivers/gpu/drm/i915/display/intel_display_wa.h
> @@ -21,4 +21,13 @@ static inline bool intel_display_needs_wa_16023588340(struct intel_display *disp
>  bool intel_display_needs_wa_16023588340(struct intel_display *display);
>  #endif
>  
> +enum intel_display_wa {
> +	INTEL_DISPLAY_WA_16023588340,

How is anyone supposed to keep track of these random numbers
and what they mean?

The only time I want to see these numbers is if I really have to
open the spec/hsd for it to double check some details. Othwerwise
it just seems like pointless noise that makes it harder to follow
the code/figure out what the heck is going on.

> +};
> +
> +bool __intel_display_wa(struct intel_display *display, enum intel_display_wa wa);
> +
> +#define intel_display_wa(__display, __wa) \
> +	__intel_display_wa((__display), INTEL_DISPLAY_WA_##__wa)
> +
>  #endif
> diff --git a/drivers/gpu/drm/i915/display/intel_fbc.c b/drivers/gpu/drm/i915/display/intel_fbc.c
> index 6e26cb4c5724..e2e03af520b2 100644
> --- a/drivers/gpu/drm/i915/display/intel_fbc.c
> +++ b/drivers/gpu/drm/i915/display/intel_fbc.c
> @@ -1464,7 +1464,7 @@ static int intel_fbc_check_plane(struct intel_atomic_state *state,
>  		return 0;
>  	}
>  
> -	if (intel_display_needs_wa_16023588340(display)) {
> +	if (intel_display_wa(display, 16023588340)) {
>  		plane_state->no_fbc_reason = "Wa_16023588340";

This here for instance is completely useless. I have no idea what that
w/a is about or why it requires FBC to be disabled. And if I jump into
intel_display_needs_wa_16023588340() I am none the wiser.

>  		return 0;
>  	}
> -- 
> 2.45.2

-- 
Ville Syrjälä
Intel