Re: [PATCH 1/8] drm/i915: move SKL clock gating init to display

[Jani Nikula <jani.nikula@linux.intel.com>]

On Tue, 24 Mar 2026, Luca Coelho <luciano.coelho@intel.com> wrote:
> Move the SKL-specific display clock gating programming into a new file
> inside display.
>
> This removes dependency from intel_clock_gating.c to the display's
> intel_pch.h file, so we can remove the include statement.
>
> Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
> ---
>  drivers/gpu/drm/i915/Makefile                 |  1 +
>  .../i915/display/intel_display_clock_gating.c | 19 +++++++++++++++++++
>  .../i915/display/intel_display_clock_gating.h | 17 +++++++++++++++++
>  drivers/gpu/drm/i915/intel_clock_gating.c     |  8 ++------
>  4 files changed, 39 insertions(+), 6 deletions(-)
>  create mode 100644 drivers/gpu/drm/i915/display/intel_display_clock_gating.c
>  create mode 100644 drivers/gpu/drm/i915/display/intel_display_clock_gating.h
>
> diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
> index be976a90c5a6..89232873d4b7 100644
> --- a/drivers/gpu/drm/i915/Makefile
> +++ b/drivers/gpu/drm/i915/Makefile
> @@ -254,6 +254,7 @@ i915-y += \
>  	display/intel_crtc_state_dump.o \
>  	display/intel_cursor.o \
>  	display/intel_dbuf_bw.o \
> +	display/intel_display_clock_gating.o \
>  	display/intel_display.o \
>  	display/intel_display_conversion.o \
>  	display/intel_display_driver.o \
> diff --git a/drivers/gpu/drm/i915/display/intel_display_clock_gating.c b/drivers/gpu/drm/i915/display/intel_display_clock_gating.c
> new file mode 100644
> index 000000000000..4a94593335e0
> --- /dev/null
> +++ b/drivers/gpu/drm/i915/display/intel_display_clock_gating.c
> @@ -0,0 +1,19 @@
> +// SPDX-License-Identifier: MIT
> +/*
> + * Copyright 2026 Intel Corporation
> + */
> +
> +#include <drm/intel/intel_gmd_misc_regs.h>
> +
> +#include "intel_de.h"
> +#include "intel_display_clock_gating.h"
> +#include "intel_display_regs.h"
> +
> +void intel_display_skl_init_clock_gating(struct intel_display *display)
> +{
> +	/*
> +	 * WaFbcTurnOffFbcWatermark:skl
> +	 * Display WA #0562: skl
> +	 */
> +	intel_de_rmw(display, DISP_ARB_CTL, 0, DISP_FBC_WM_DIS);
> +}
> diff --git a/drivers/gpu/drm/i915/display/intel_display_clock_gating.h b/drivers/gpu/drm/i915/display/intel_display_clock_gating.h
> new file mode 100644
> index 000000000000..c93997417dcb
> --- /dev/null
> +++ b/drivers/gpu/drm/i915/display/intel_display_clock_gating.h
> @@ -0,0 +1,17 @@
> +/* SPDX-License-Identifier: MIT */
> +/*
> + * Copyright 2026 Intel Corporation
> + */
> +
> +#ifndef __INTEL_DISPLAY_CLOCK_GATING_H__
> +#define __INTEL_DISPLAY_CLOCK_GATING_H__
> +
> +struct intel_display;
> +
> +#ifdef I915
> +void intel_display_skl_init_clock_gating(struct intel_display *display);
> +#else
> +static inline void intel_display_skl_init_clock_gating(struct intel_display *display) {}
> +#endif

I don't think we should add any of this #ifdef I915 stuff, because the
next step will be to remove all of them anyway.

Currently they'll only get called for i915, but their existence in xe
doesn't matter. And eventually they'll be part of the display module.

BR,
Jani.


> +
> +#endif /* __INTEL_DISPLAY_CLOCK_GATING_H__ */
> diff --git a/drivers/gpu/drm/i915/intel_clock_gating.c b/drivers/gpu/drm/i915/intel_clock_gating.c
> index ee2489a2fbe7..454334fef5e7 100644
> --- a/drivers/gpu/drm/i915/intel_clock_gating.c
> +++ b/drivers/gpu/drm/i915/intel_clock_gating.c
> @@ -31,9 +31,9 @@
>  
>  #include "display/i9xx_plane_regs.h"
>  #include "display/intel_display.h"
> +#include "display/intel_display_clock_gating.h"
>  #include "display/intel_display_core.h"
>  #include "display/intel_display_regs.h"
> -#include "display/intel_pch.h"
>  #include "gt/intel_engine_regs.h"
>  #include "gt/intel_gt.h"
>  #include "gt/intel_gt_mcr.h"
> @@ -349,11 +349,7 @@ static void skl_init_clock_gating(struct drm_i915_private *i915)
>  	/* WAC6entrylatency:skl */
>  	intel_uncore_rmw(&i915->uncore, FBC_LLC_READ_CTRL, 0, FBC_LLC_FULLY_OPEN);
>  
> -	/*
> -	 * WaFbcTurnOffFbcWatermark:skl
> -	 * Display WA #0562: skl
> -	 */
> -	intel_uncore_rmw(&i915->uncore, DISP_ARB_CTL, 0, DISP_FBC_WM_DIS);
> +	intel_display_skl_init_clock_gating(i915->display);
>  }
>  
>  static void bdw_init_clock_gating(struct drm_i915_private *i915)

-- 
Jani Nikula, Intel