Re: [PATCH 09/19] drm/i915/guc: Convert engine record to iosys_map

[Thomas Zimmermann <tzimmermann@suse.de>]

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Hi

Am 04.02.22 um 18:44 schrieb Lucas De Marchi:
> Use iosys_map to read fields from the dma_blob so access to IO and
> system memory is abstracted away.
> 
> Cc: Matt Roper <matthew.d.roper@intel.com>
> Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
> Cc: Daniel Vetter <daniel@ffwll.ch>
> Cc: John Harrison <John.C.Harrison@Intel.com>
> Cc: Matthew Brost <matthew.brost@intel.com>
> Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
> Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
> ---
>   drivers/gpu/drm/i915/gt/uc/intel_guc_ads.c      | 14 ++++++--------
>   drivers/gpu/drm/i915/gt/uc/intel_guc_ads.h      |  3 ++-
>   .../gpu/drm/i915/gt/uc/intel_guc_submission.c   | 17 ++++++++++-------
>   3 files changed, 18 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_ads.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_ads.c
> index 6311b9da87e4..1d21a2d457e0 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_ads.c
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_ads.c
> @@ -698,18 +698,16 @@ void intel_guc_ads_reset(struct intel_guc *guc)
>   
>   u32 intel_guc_engine_usage_offset(struct intel_guc *guc)
>   {
> -	struct __guc_ads_blob *blob = guc->ads_blob;
> -	u32 base = intel_guc_ggtt_offset(guc, guc->ads_vma);
> -	u32 offset = base + ptr_offset(blob, engine_usage);
> -
> -	return offset;
> +	return intel_guc_ggtt_offset(guc, guc->ads_vma) +
> +		offsetof(struct __guc_ads_blob, engine_usage);
>   }
>   
> -struct guc_engine_usage_record *intel_guc_engine_usage(struct intel_engine_cs *engine)
> +struct iosys_map intel_guc_engine_usage_record_map(struct intel_engine_cs *engine)
>   {
>   	struct intel_guc *guc = &engine->gt->uc.guc;
> -	struct __guc_ads_blob *blob = guc->ads_blob;
>   	u8 guc_class = engine_class_to_guc_class(engine->class);
> +	size_t offset = offsetof(struct __guc_ads_blob,
> +				 engine_usage.engines[guc_class][ilog2(engine->logical_mask)]);
>   
> -	return &blob->engine_usage.engines[guc_class][ilog2(engine->logical_mask)];
> +	return IOSYS_MAP_INIT_OFFSET(&guc->ads_map, offset);

Here's one of the few cases where you can legitimately make a copy of an 
iosys_map buffer and call iosys_map_incr() on it. Saves you the 
IOSYS_MAP_INIT_OFFSET().

Best regards
Thomas

>   }
> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_ads.h b/drivers/gpu/drm/i915/gt/uc/intel_guc_ads.h
> index e74c110facff..1c64f4d6ea21 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_ads.h
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_ads.h
> @@ -7,6 +7,7 @@
>   #define _INTEL_GUC_ADS_H_
>   
>   #include <linux/types.h>
> +#include <linux/iosys-map.h>
>   
>   struct intel_guc;
>   struct drm_printer;
> @@ -18,7 +19,7 @@ void intel_guc_ads_init_late(struct intel_guc *guc);
>   void intel_guc_ads_reset(struct intel_guc *guc);
>   void intel_guc_ads_print_policy_info(struct intel_guc *guc,
>   				     struct drm_printer *p);
> -struct guc_engine_usage_record *intel_guc_engine_usage(struct intel_engine_cs *engine);
> +struct iosys_map intel_guc_engine_usage_record_map(struct intel_engine_cs *engine);
>   u32 intel_guc_engine_usage_offset(struct intel_guc *guc);
>   
>   #endif
> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> index b3a429a92c0d..6d34842f68b4 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> @@ -1139,6 +1139,9 @@ __extend_last_switch(struct intel_guc *guc, u64 *prev_start, u32 new_start)
>   	*prev_start = ((u64)gt_stamp_hi << 32) | new_start;
>   }
>   
> +#define record_read(map_, field_) \
> +	iosys_map_rd_field(map_, struct guc_engine_usage_record, field_)
> +
>   /*
>    * GuC updates shared memory and KMD reads it. Since this is not synchronized,
>    * we run into a race where the value read is inconsistent. Sometimes the
> @@ -1153,17 +1156,17 @@ __extend_last_switch(struct intel_guc *guc, u64 *prev_start, u32 new_start)
>   static void __get_engine_usage_record(struct intel_engine_cs *engine,
>   				      u32 *last_in, u32 *id, u32 *total)
>   {
> -	struct guc_engine_usage_record *rec = intel_guc_engine_usage(engine);
> +	struct iosys_map rec_map = intel_guc_engine_usage_record_map(engine);
>   	int i = 0;
>   
>   	do {
> -		*last_in = READ_ONCE(rec->last_switch_in_stamp);
> -		*id = READ_ONCE(rec->current_context_index);
> -		*total = READ_ONCE(rec->total_runtime);
> +		*last_in = record_read(&rec_map, last_switch_in_stamp);
> +		*id = record_read(&rec_map, current_context_index);
> +		*total = record_read(&rec_map, total_runtime);
>   
> -		if (READ_ONCE(rec->last_switch_in_stamp) == *last_in &&
> -		    READ_ONCE(rec->current_context_index) == *id &&
> -		    READ_ONCE(rec->total_runtime) == *total)
> +		if (record_read(&rec_map, last_switch_in_stamp) == *last_in &&
> +		    record_read(&rec_map, current_context_index) == *id &&
> +		    record_read(&rec_map, total_runtime) == *total)
>   			break;
>   	} while (++i < 6);
>   }

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Ivo Totev

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