Re: [PATCH v7 1/6] drm/panthor: Expose GPU page sizes to UM

Steven Price
2026-04-15T15:19:43Z

On 15/04/2026 12:28, Adrián Larumbe wrote:
> In future commits that will implement repeated mappings, only repeat
> values multiple of GPU page sizes will be tolerated. That means these
> values must be made known to UM. Do it through a queriable GPU info
> value.
>
> Signed-off-by: Adrián Larumbe <adrian.larumbe@collabora.com>

Reviewed-by: Steven Price <steven.price@arm.com>

> ---
> drivers/gpu/drm/panthor/panthor_device.h | 3 +++
> drivers/gpu/drm/panthor/panthor_drv.c | 8 ++++++++
> drivers/gpu/drm/panthor/panthor_mmu.c | 9 ++++++++-
> include/uapi/drm/panthor_drm.h | 13 +++++++++++++
> 4 files changed, 32 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/panthor/panthor_device.h b/drivers/gpu/drm/panthor/panthor_device.h
> index 5cba272f9b4d..d856a4fe1d61 100644
> --- a/drivers/gpu/drm/panthor/panthor_device.h
> +++ b/drivers/gpu/drm/panthor/panthor_device.h
> @@ -158,6 +158,9 @@ struct panthor_device {
> /** @csif_info: Command stream interface information. */
> struct drm_panthor_csif_info csif_info;
>
> + /** @mmu_info: MMU info */
> + struct drm_panthor_mmu_info mmu_info;
> +
> /** @hw: GPU-specific data. */
> struct panthor_hw *hw;
>
> diff --git a/drivers/gpu/drm/panthor/panthor_drv.c b/drivers/gpu/drm/panthor/panthor_drv.c
> index 73fc983dc9b4..a8090bc4e33c 100644
> --- a/drivers/gpu/drm/panthor/panthor_drv.c
> +++ b/drivers/gpu/drm/panthor/panthor_drv.c
> @@ -175,6 +175,7 @@ panthor_get_uobj_array(const struct drm_panthor_obj_array *in, u32 min_stride,
> _Generic(_obj_name, \
> PANTHOR_UOBJ_DECL(struct drm_panthor_gpu_info, tiler_present), \
> PANTHOR_UOBJ_DECL(struct drm_panthor_csif_info, pad), \
> + PANTHOR_UOBJ_DECL(struct drm_panthor_mmu_info, page_size_bitmap), \
> PANTHOR_UOBJ_DECL(struct drm_panthor_timestamp_info, current_timestamp), \
> PANTHOR_UOBJ_DECL(struct drm_panthor_group_priorities_info, pad), \
> PANTHOR_UOBJ_DECL(struct drm_panthor_sync_op, timeline_value), \
> @@ -946,6 +947,10 @@ static int panthor_ioctl_dev_query(struct drm_device *ddev, void *data, struct d
> args->size = sizeof(ptdev->csif_info);
> return 0;
>
> + case DRM_PANTHOR_DEV_QUERY_MMU_INFO:
> + args->size = sizeof(ptdev->mmu_info);
> + return 0;
> +
> case DRM_PANTHOR_DEV_QUERY_TIMESTAMP_INFO:
> args->size = sizeof(timestamp_info);
> return 0;
> @@ -966,6 +971,9 @@ static int panthor_ioctl_dev_query(struct drm_device *ddev, void *data, struct d
> case DRM_PANTHOR_DEV_QUERY_CSIF_INFO:
> return PANTHOR_UOBJ_SET(args->pointer, args->size, ptdev->csif_info);
>
> + case DRM_PANTHOR_DEV_QUERY_MMU_INFO:
> + return PANTHOR_UOBJ_SET(args->pointer, args->size, ptdev->mmu_info);
> +
> case DRM_PANTHOR_DEV_QUERY_TIMESTAMP_INFO:
> ret = copy_struct_from_user(&timestamp_info,
> sizeof(timestamp_info),
> diff --git a/drivers/gpu/drm/panthor/panthor_mmu.c b/drivers/gpu/drm/panthor/panthor_mmu.c
> index bd41c892beb7..01577be88933 100644
> --- a/drivers/gpu/drm/panthor/panthor_mmu.c
> +++ b/drivers/gpu/drm/panthor/panthor_mmu.c
> @@ -2769,7 +2769,7 @@ panthor_vm_create(struct panthor_device *ptdev, bool for_mcu,
> refcount_set(&vm->as.active_cnt, 0);
>
> pgtbl_cfg = (struct io_pgtable_cfg) {
> - .pgsize_bitmap = SZ_4K | SZ_2M,
> + .pgsize_bitmap = ptdev->mmu_info.page_size_bitmap,
> .ias = va_bits,
> .oas = pa_bits,
> .coherent_walk = ptdev->coherent,
> @@ -3214,6 +3214,11 @@ static void panthor_mmu_release_wq(struct drm_device *ddev, void *res)
> destroy_workqueue(res);
> }
>
> +static void panthor_mmu_info_init(struct panthor_device *ptdev)
> +{
> + ptdev->mmu_info.page_size_bitmap = SZ_4K | SZ_2M;
> +}
> +
> /**
> * panthor_mmu_init() - Initialize the MMU logic.
> * @ptdev: Device.
> @@ -3226,6 +3231,8 @@ int panthor_mmu_init(struct panthor_device *ptdev)
> struct panthor_mmu *mmu;
> int ret, irq;
>
> + panthor_mmu_info_init(ptdev);
> +
> mmu = drmm_kzalloc(&ptdev->base, sizeof(*mmu), GFP_KERNEL);
> if (!mmu)
> return -ENOMEM;
> diff --git a/include/uapi/drm/panthor_drm.h b/include/uapi/drm/panthor_drm.h
> index 0e455d91e77d..dc2704fc2829 100644
> --- a/include/uapi/drm/panthor_drm.h
> +++ b/include/uapi/drm/panthor_drm.h
> @@ -246,6 +246,9 @@ enum drm_panthor_dev_query_type {
> /** @DRM_PANTHOR_DEV_QUERY_CSIF_INFO: Query command-stream interface information. */
> DRM_PANTHOR_DEV_QUERY_CSIF_INFO,
>
> + /** @DRM_PANTHOR_DEV_QUERY_MMU_INFO: Query MMU information. */
> + DRM_PANTHOR_DEV_QUERY_MMU_INFO,
> +
> /** @DRM_PANTHOR_DEV_QUERY_TIMESTAMP_INFO: Query timestamp information. */
> DRM_PANTHOR_DEV_QUERY_TIMESTAMP_INFO,
>
> @@ -487,6 +490,16 @@ struct drm_panthor_timestamp_info {
> __u64 cpu_timestamp_nsec;
> };
>
> +/**
> + * struct drm_panthor_mmu_info - MMU information
> + *
> + * Structure grouping all queryable information relating to the MMU.
> + */
> +struct drm_panthor_mmu_info {
> + /** @page_size_bitmap: Allowed page sizes */
> + __u64 page_size_bitmap;
> +};
> +
> /**
> * struct drm_panthor_group_priorities_info - Group priorities information
> *