Re: [PATCH v3 20/21] drm/i915/display: perform transient flush

[Nirmoy Das <nirmoy.das@linux.intel.com>]

Hi Matt,

On 4/15/2024 7:07 PM, Matt Roper wrote:
> On Mon, Apr 15, 2024 at 01:44:22PM +0530, Balasubramani Vivekanandan wrote:
>> From: Matthew Auld <matthew.auld@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@xe-pat@display-vs-wb-transient
> Has the IGT patch for this been sent yet?

Yes, the test seems to be available 
https://gitlab.freedesktop.org/drm/igt-gpu-tools/-/blob/master/tests/intel/xe_pat.c#L728 



Regards,

Nirmoy

>    If not, we should probably
> make sure that happens soon, and then use the CI Test-with: thing if
> there winds up being another revision of this series so that this will
> be included in the CI results.
>
> Anyway, the changes here look good to me,
>
> Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
>
>> Signed-off-by: Matthew Auld <matthew.auld@intel.com>
>> Signed-off-by: Balasubramani Vivekanandan <balasubramani.vivekanandan@intel.com>
>> Acked-by: Nirmoy Das <nirmoy.das@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 67697d9a559c..4fc46edcb4ad 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"
>> @@ -7242,6 +7243,8 @@ 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 6015c9e41f24..97a8674cdd76 100644
>> --- a/drivers/gpu/drm/xe/Makefile
>> +++ b/drivers/gpu/drm/xe/Makefile
>> @@ -198,7 +198,8 @@ 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);
>> +}
>> -- 
>> 2.25.1
>>