drm/panthor: Make sure the tiler initial/max chunks are consistent

It doesn't make sense to have a maximum number of chunks smaller than
the initial number of chunks attached to the context.

Fix the uAPI header to reflect the new constraint, and mention the
undocumented "initial_chunk_count > 0" constraint while at it.

v3:
- Add R-b

v2:
- Fix the check

Fixes: 9cca48fa4f89 ("drm/panthor: Add the heap logical block")
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Liviu Dudau <liviu.dudau@arm.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240502165158.1458959-3-boris.brezillon@collabora.com

diff --git a/drivers/gpu/drm/panthor/panthor_heap.c b/drivers/gpu/drm/panthor/panthor_heap.c
index c3c0ba744937da9e7f08ff69732e63ecb7314f3f..3be86ec383d6b68fc7f9c4a742bd897537938a2f 100644 (file)
--- a/drivers/gpu/drm/panthor/panthor_heap.c
+++ b/drivers/gpu/drm/panthor/panthor_heap.c
@@ -281,6 +281,9 @@ int panthor_heap_create(struct panthor_heap_pool *pool,
        if (initial_chunk_count == 0)
                return -EINVAL;
 
+       if (initial_chunk_count > max_chunks)
+               return -EINVAL;
+
        if (hweight32(chunk_size) != 1 ||
            chunk_size < SZ_256K || chunk_size > SZ_2M)
                return -EINVAL;

diff --git a/include/uapi/drm/panthor_drm.h b/include/uapi/drm/panthor_drm.h
index dadb05ab1235839cc828c94a73614d9a76a4be25..5db80a0682d5c86c793d9a384db08b2985a1b795 100644 (file)
--- a/include/uapi/drm/panthor_drm.h
+++ b/include/uapi/drm/panthor_drm.h
@@ -895,13 +895,17 @@ struct drm_panthor_tiler_heap_create {
        /** @vm_id: VM ID the tiler heap should be mapped to */
        __u32 vm_id;
 
-       /** @initial_chunk_count: Initial number of chunks to allocate. */
+       /** @initial_chunk_count: Initial number of chunks to allocate. Must be at least one. */
        __u32 initial_chunk_count;
 
        /** @chunk_size: Chunk size. Must be a power of two at least 256KB large. */
        __u32 chunk_size;
 
-       /** @max_chunks: Maximum number of chunks that can be allocated. */
+       /**
+        * @max_chunks: Maximum number of chunks that can be allocated.
+        *
+        * Must be at least @initial_chunk_count.
+        */
        __u32 max_chunks;
 
        /**