On Fri, 22 Aug 2025 10:29:11 -0400
Faith Ekstrand <fa...@gfxstrand.net> wrote:
> From: Loïc Molinari <loic.molin...@collabora.com>
>
> Signed-off-by: Loïc Molinari <loic.molin...@collabora.com>
> Signed-off-by: Faith Ekstrand <faith.ekstr...@collabora.com>
> ---
> drivers/gpu/drm/panthor/panthor_drv.c | 7 ++++++-
> drivers/gpu/drm/panthor/panthor_gem.c | 3 +++
> include/uapi/drm/panthor_drm.h | 10 ++++++++++
> 3 files changed, 19 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/panthor/panthor_drv.c
> b/drivers/gpu/drm/panthor/panthor_drv.c
> index 1116f2d2826e..06ae6a2aeb16 100644
> --- a/drivers/gpu/drm/panthor/panthor_drv.c
> +++ b/drivers/gpu/drm/panthor/panthor_drv.c
> @@ -899,7 +899,8 @@ static int panthor_ioctl_vm_destroy(struct drm_device
> *ddev, void *data,
> return panthor_vm_pool_destroy_vm(pfile->vms, args->id);
> }
>
> -#define PANTHOR_BO_FLAGS DRM_PANTHOR_BO_NO_MMAP
> +#define PANTHOR_BO_FLAGS (DRM_PANTHOR_BO_NO_MMAP | \
> + DRM_PANTHOR_BO_WB_MMAP)
>
> static int panthor_ioctl_bo_create(struct drm_device *ddev, void *data,
> struct drm_file *file)
> @@ -918,6 +919,10 @@ static int panthor_ioctl_bo_create(struct drm_device
> *ddev, void *data,
> goto out_dev_exit;
> }
>
> + if ((args->flags & DRM_PANTHOR_BO_NO_MMAP) &&
> + (args->flags & DRM_PANTHOR_BO_WB_MMAP))
> + return -EINVAL;
I know it's obvious, but I'd still add a comment explaining why WB_MMAP
can't be set if NO_MMAP is.
> +
> if (args->exclusive_vm_id) {
> vm = panthor_vm_pool_get_vm(pfile->vms, args->exclusive_vm_id);
> if (!vm) {
> diff --git a/drivers/gpu/drm/panthor/panthor_gem.c
> b/drivers/gpu/drm/panthor/panthor_gem.c
> index a123bc740ba1..530bad12d545 100644
> --- a/drivers/gpu/drm/panthor/panthor_gem.c
> +++ b/drivers/gpu/drm/panthor/panthor_gem.c
> @@ -283,6 +283,9 @@ panthor_gem_create_with_handle(struct drm_file *file,
> bo = to_panthor_bo(&shmem->base);
> bo->flags = flags;
>
> + if (flags & DRM_PANTHOR_BO_WB_MMAP)
> + shmem->map_wc = false;
> +
> if (exclusive_vm) {
> bo->exclusive_vm_root_gem = panthor_vm_root_gem(exclusive_vm);
> drm_gem_object_get(bo->exclusive_vm_root_gem);
> diff --git a/include/uapi/drm/panthor_drm.h b/include/uapi/drm/panthor_drm.h
> index e1f43deb7eca..bf47369c0220 100644
> --- a/include/uapi/drm/panthor_drm.h
> +++ b/include/uapi/drm/panthor_drm.h
> @@ -635,6 +635,16 @@ struct drm_panthor_vm_get_state {
> enum drm_panthor_bo_flags {
> /** @DRM_PANTHOR_BO_NO_MMAP: The buffer object will never be CPU-mapped
> in userspace. */
> DRM_PANTHOR_BO_NO_MMAP = (1 << 0),
> +
> + /**
> + *@DRM_PANTHOR_BO_WB_MMAP: Force "Write-Back Cacheable" CPU mapping.
^ missing space after '*'
> + *
> + * CPU map the buffer object in userspace by forcing the "Write-Back
> + * Cacheable" cacheability attribute. The mapping otherwise uses the
> + * "Non-Cacheable" attribute if the ACE-Lite coherency protocol isn't
> + * supported by the GPU.
> + */
> + DRM_PANTHOR_BO_WB_MMAP = (1 << 1),
We probably want to expose the coherency caps before introducing this
flag (through some DEV_QUERY argument), so the UMD knows when it can
skip cache maintenance operations.
> };
>
> /**
