Re: [PATCH] drm/panthor: use defines for sync flags

[Mihail Atanassov <mihail.atanassov@xxxxxxx>]

Hi Erik,

On 29/10/2024 09:46, Erik Faye-Lund wrote:
> Enums are always signed, and assigning 1u << 31 to it invokes
> implementation defined behavior. It's not a great idea to depend on this
> in the UAPI, and it turns out no other UAPI does either.
>
> So let's do what other UAPI does, and use defines instead. This way we
> won't get unexpected issues if compiling user-space with a compiler with
> a different implementation-defined behavior here.
> ---
>   include/uapi/drm/panthor_drm.h | 44 +++++++++++++++++++++-------------
>   1 file changed, 28 insertions(+), 16 deletions(-)
>
> diff --git a/include/uapi/drm/panthor_drm.h b/include/uapi/drm/panthor_drm.h
> index 87c9cb555dd1d..a2e348f901376 100644
> --- a/include/uapi/drm/panthor_drm.h
> +++ b/include/uapi/drm/panthor_drm.h
> @@ -209,27 +209,39 @@ struct drm_panthor_obj_array {
>   	{ .stride = sizeof((ptr)[0]), .count = (cnt), .array = (__u64)(uintptr_t)(ptr) }
>   
>   /**
> - * enum drm_panthor_sync_op_flags - Synchronization operation flags.
> + * DRM_PANTHOR_SYNC_OP_HANDLE_TYPE_MASK
> + *
> + * Synchronization handle type mask.
>    */
> -enum drm_panthor_sync_op_flags {
> -	/** @DRM_PANTHOR_SYNC_OP_HANDLE_TYPE_MASK: Synchronization handle type mask. */
> -	DRM_PANTHOR_SYNC_OP_HANDLE_TYPE_MASK = 0xff,
> +#define DRM_PANTHOR_SYNC_OP_HANDLE_TYPE_MASK              0xff
>   
> -	/** @DRM_PANTHOR_SYNC_OP_HANDLE_TYPE_SYNCOBJ: Synchronization object type. */
> -	DRM_PANTHOR_SYNC_OP_HANDLE_TYPE_SYNCOBJ = 0,
> +/**
> + * DRM_PANTHOR_SYNC_OP_HANDLE_TYPE_SYNCOBJ
> + *
> + * Synchronization object type.
> + */
> +#define DRM_PANTHOR_SYNC_OP_HANDLE_TYPE_SYNCOBJ           0
>   
> -	/**
> -	 * @DRM_PANTHOR_SYNC_OP_HANDLE_TYPE_TIMELINE_SYNCOBJ: Timeline synchronization
> -	 * object type.
> -	 */
> -	DRM_PANTHOR_SYNC_OP_HANDLE_TYPE_TIMELINE_SYNCOBJ = 1,
> +/**
> + * DRM_PANTHOR_SYNC_OP_HANDLE_TYPE_TIMELINE_SYNCOBJ
> + *
> + * Timeline synchronization object type.
> + */
> +#define DRM_PANTHOR_SYNC_OP_HANDLE_TYPE_TIMELINE_SYNCOBJ  1
>   
> -	/** @DRM_PANTHOR_SYNC_OP_WAIT: Wait operation. */
> -	DRM_PANTHOR_SYNC_OP_WAIT = 0 << 31,
> +/**
> + * DRM_PANTHOR_SYNC_OP_WAIT
> + *
> + * Wait operation.
> + */
> +#define DRM_PANTHOR_SYNC_OP_WAIT    (0 << 31)

[nit] 0u << 31, to have the same signedness as SYNC_OP_SIGNAL.

>   
> -	/** @DRM_PANTHOR_SYNC_OP_SIGNAL: Signal operation. */
> -	DRM_PANTHOR_SYNC_OP_SIGNAL = (int)(1u << 31),
> -};
> +/**
> + * DRM_PANTHOR_SYNC_OP_SIGNAL
> + *
> + * Signal operation.
> + */
> +#define DRM_PANTHOR_SYNC_OP_SIGNAL  (1u << 31)
>   
>   /**
>    * struct drm_panthor_sync_op - Synchronization operation.

--
Mihail Atanassov <mihail.atanassov@xxxxxxx>