[PATCH v2 24/25] drm/i915/display: perform transient flush

[Nirmoy Das]

+Jouni

On 4/3/2024 1:22 PM, Balasubramani Vivekanandan wrote:
> From: Matthew Auld <matthew.auld at intel.com>
>
> Perform manual transient cache flush prior to flip and at the end of
> frontbuffer_flush. This is needed to ensure display engine doesn't see
> garbage if the surface is L3:XD dirty.
>
> Testcase: igt at xe-pat@display-vs-wb-transient
> Signed-off-by: Matthew Auld <matthew.auld at intel.com>
> Signed-off-by: Balasubramani Vivekanandan <balasubramani.vivekanandan at intel.com>
Acked-by: Nirmoy Das <nirmoy.das at intel.com>
> ---
>   drivers/gpu/drm/i915/display/intel_display.c  |  3 +++
>   .../gpu/drm/i915/display/intel_frontbuffer.c  |  2 ++
>   drivers/gpu/drm/i915/display/intel_tdf.h      | 25 +++++++++++++++++++
>   drivers/gpu/drm/xe/Makefile                   |  3 ++-
>   drivers/gpu/drm/xe/display/xe_tdf.c           | 13 ++++++++++
>   5 files changed, 45 insertions(+), 1 deletion(-)
>   create mode 100644 drivers/gpu/drm/i915/display/intel_tdf.h
>   create mode 100644 drivers/gpu/drm/xe/display/xe_tdf.c
>
> diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
> index aed25890b6f5..0a720e9d12a7 100644
> --- a/drivers/gpu/drm/i915/display/intel_display.c
> +++ b/drivers/gpu/drm/i915/display/intel_display.c
> @@ -110,6 +110,7 @@
>   #include "intel_sdvo.h"
>   #include "intel_snps_phy.h"
>   #include "intel_tc.h"
> +#include "intel_tdf.h"
>   #include "intel_tv.h"
>   #include "intel_vblank.h"
>   #include "intel_vdsc.h"
> @@ -7095,6 +7096,8 @@ static void intel_atomic_commit_tail(struct intel_atomic_state *state)
>   
>   	intel_atomic_commit_fence_wait(state);
>   
> +	intel_td_flush(dev_priv);
> +
>   	drm_atomic_helper_wait_for_dependencies(&state->base);
>   	drm_dp_mst_atomic_wait_for_dependencies(&state->base);
>   	intel_atomic_global_state_wait_for_dependencies(state);
> diff --git a/drivers/gpu/drm/i915/display/intel_frontbuffer.c b/drivers/gpu/drm/i915/display/intel_frontbuffer.c
> index 2ea37c0414a9..4923c340a0b6 100644
> --- a/drivers/gpu/drm/i915/display/intel_frontbuffer.c
> +++ b/drivers/gpu/drm/i915/display/intel_frontbuffer.c
> @@ -65,6 +65,7 @@
>   #include "intel_fbc.h"
>   #include "intel_frontbuffer.h"
>   #include "intel_psr.h"
> +#include "intel_tdf.h"
>   
>   /**
>    * frontbuffer_flush - flush frontbuffer
> @@ -93,6 +94,7 @@ static void frontbuffer_flush(struct drm_i915_private *i915,
>   	trace_intel_frontbuffer_flush(i915, frontbuffer_bits, origin);
>   
>   	might_sleep();
> +	intel_td_flush(i915);
>   	intel_drrs_flush(i915, frontbuffer_bits);
>   	intel_psr_flush(i915, frontbuffer_bits, origin);
>   	intel_fbc_flush(i915, frontbuffer_bits, origin);
> diff --git a/drivers/gpu/drm/i915/display/intel_tdf.h b/drivers/gpu/drm/i915/display/intel_tdf.h
> new file mode 100644
> index 000000000000..353cde21f6c2
> --- /dev/null
> +++ b/drivers/gpu/drm/i915/display/intel_tdf.h
> @@ -0,0 +1,25 @@
> +/* SPDX-License-Identifier: MIT */
> +/*
> + * Copyright © 2024 Intel Corporation
> + */
> +
> +#ifndef __INTEL_TDF_H__
> +#define __INTEL_TDF_H__
> +
> +/*
> + * TDF (Transient-Data-Flush) is needed for Xe2+ where special L3:XD caching can
> + * be enabled through various PAT index modes. Idea is to use this caching mode
> + * when for example rendering onto the display surface, with the promise that
> + * KMD will ensure transient cache entries are always flushed by the time we do
> + * the display flip, since display engine is never coherent with CPU/GPU caches.
> + */
> +
> +struct drm_i915_private;
> +
> +#ifdef I915
> +static inline void intel_td_flush(struct drm_i915_private *i915) {}
> +#else
> +void intel_td_flush(struct drm_i915_private *i915);
> +#endif
> +
> +#endif
> diff --git a/drivers/gpu/drm/xe/Makefile b/drivers/gpu/drm/xe/Makefile
> index e5b1715f721e..401a4492c625 100644
> --- a/drivers/gpu/drm/xe/Makefile
> +++ b/drivers/gpu/drm/xe/Makefile
> @@ -196,7 +196,8 @@ xe-$(CONFIG_DRM_XE_DISPLAY) += \
>   	display/xe_dsb_buffer.o \
>   	display/xe_fb_pin.o \
>   	display/xe_hdcp_gsc.o \
> -	display/xe_plane_initial.o
> +	display/xe_plane_initial.o \
> +	display/xe_tdf.o
>   
>   # SOC code shared with i915
>   xe-$(CONFIG_DRM_XE_DISPLAY) += \
> diff --git a/drivers/gpu/drm/xe/display/xe_tdf.c b/drivers/gpu/drm/xe/display/xe_tdf.c
> new file mode 100644
> index 000000000000..2c0d4e144e09
> --- /dev/null
> +++ b/drivers/gpu/drm/xe/display/xe_tdf.c
> @@ -0,0 +1,13 @@
> +// SPDX-License-Identifier: MIT
> +/*
> + * Copyright © 2024 Intel Corporation
> + */
> +
> +#include "xe_device.h"
> +#include "intel_display_types.h"
> +#include "intel_tdf.h"
> +
> +void intel_td_flush(struct drm_i915_private *i915)
> +{
> +	xe_device_td_flush(i915);
> +}