Commit ea78ec98 authored by Boris Brezillon's avatar Boris Brezillon
Browse files

drm/panthor: Expose the selected coherency protocol to the UMD 



If we want to be able to skip CPU cache maintenance operations on
CPU-cached mappings, the UMD needs to know the kind of coherency
in place. Add a field to drm_panthor_gpu_info to do that. We can re-use
a padding field for that since this object is write-only from the
KMD perspective, and the UMD should just ignore it.

v2:
- New commit

v3:
- Make coherency protocol a real enum, not a bitmask
- Add BUILD_BUG_ON()s to make sure the values in panthor_regs.h and
  those exposed through the uAPI match

v4:
- Add Steve's R-b

v5:
- No changes

v6:
- No changes

v7:
- Fix kernel doc

v8:
- No changes

Reviewed-by: default avatarSteven Price <steven.price@arm.com>
Reviewed-by: default avatarKarunika Choo <karunika.choo@arm.com>
Link: https://patch.msgid.link/20251208100841.730527-4-boris.brezillon@collabora.com


Signed-off-by: default avatarBoris Brezillon <boris.brezillon@collabora.com>
parent 9beb8dca

drivers/gpu/drm/panthor/panthor_device.c

+9 −1
Original line number Diff line number Diff line
@@ -28,6 +28,12 @@ 


static int panthor_gpu_coherency_init(struct panthor_device *ptdev)

{

	BUILD_BUG_ON(GPU_COHERENCY_NONE != DRM_PANTHOR_GPU_COHERENCY_NONE);

	BUILD_BUG_ON(GPU_COHERENCY_ACE_LITE != DRM_PANTHOR_GPU_COHERENCY_ACE_LITE);

	BUILD_BUG_ON(GPU_COHERENCY_ACE != DRM_PANTHOR_GPU_COHERENCY_ACE);



	/* Start with no coherency, and update it if the device is flagged coherent. */

	ptdev->gpu_info.selected_coherency = GPU_COHERENCY_NONE;

	ptdev->coherent = device_get_dma_attr(ptdev->base.dev) == DEV_DMA_COHERENT;



	if (!ptdev->coherent)
@@ -37,8 +43,10 @@ static int panthor_gpu_coherency_init(struct panthor_device *ptdev) 
	 * ACE protocol has never been supported for command stream frontend GPUs.

	 */

	if ((gpu_read(ptdev, GPU_COHERENCY_FEATURES) &

		      GPU_COHERENCY_PROT_BIT(ACE_LITE)))

		      GPU_COHERENCY_PROT_BIT(ACE_LITE))) {

		ptdev->gpu_info.selected_coherency = GPU_COHERENCY_ACE_LITE;

		return 0;

	}



	drm_err(&ptdev->base, "Coherency not supported by the device");

	return -ENOTSUPP;

drivers/gpu/drm/panthor/panthor_gpu.c

+1 −1
Original line number Diff line number Diff line
@@ -51,7 +51,7 @@ struct panthor_gpu { 
static void panthor_gpu_coherency_set(struct panthor_device *ptdev)

{

	gpu_write(ptdev, GPU_COHERENCY_PROTOCOL,

		  ptdev->coherent ? GPU_COHERENCY_ACE_LITE : GPU_COHERENCY_NONE);

		  ptdev->gpu_info.selected_coherency);

}



static void panthor_gpu_l2_config_set(struct panthor_device *ptdev)

include/uapi/drm/panthor_drm.h

+36 −3
Original line number Diff line number Diff line
@@ -245,6 +245,26 @@ enum drm_panthor_dev_query_type { 
	DRM_PANTHOR_DEV_QUERY_GROUP_PRIORITIES_INFO,

};



/**

 * enum drm_panthor_gpu_coherency: Type of GPU coherency

 */

enum drm_panthor_gpu_coherency {

	/**

	 * @DRM_PANTHOR_GPU_COHERENCY_ACE_LITE: ACE Lite coherency.

	 */

	DRM_PANTHOR_GPU_COHERENCY_ACE_LITE = 0,



	/**

	 * @DRM_PANTHOR_GPU_COHERENCY_ACE: ACE coherency.

	 */

	DRM_PANTHOR_GPU_COHERENCY_ACE = 1,



	/**

	 * @DRM_PANTHOR_GPU_COHERENCY_NONE: No coherency.

	 */

	DRM_PANTHOR_GPU_COHERENCY_NONE = 31,

};



/**

 * struct drm_panthor_gpu_info - GPU information

 *
@@ -301,7 +321,16 @@ struct drm_panthor_gpu_info { 
	 */

	__u32 thread_max_barrier_size;



	/** @coherency_features: Coherency features. */

	/**

	 * @coherency_features: Coherency features.

	 *

	 * Combination of drm_panthor_gpu_coherency flags.

	 *

	 * Note that this is just what the coherency protocols supported by the

	 * GPU, but the actual coherency in place depends on the SoC

	 * integration and is reflected by

	 * drm_panthor_gpu_info::selected_coherency.

	 */

	__u32 coherency_features;



	/** @texture_features: Texture features. */
@@ -310,8 +339,12 @@ struct drm_panthor_gpu_info { 
	/** @as_present: Bitmask encoding the number of address-space exposed by the MMU. */

	__u32 as_present;



	/** @pad0: MBZ. */

	__u32 pad0;

	/**

	 * @select_coherency: Coherency selected for this device.

	 *

	 * One of drm_panthor_gpu_coherency.

	 */

	__u32 selected_coherency;



	/** @shader_present: Bitmask encoding the shader cores exposed by the GPU. */

	__u64 shader_present;