Re: [PATCH v2 3/3] drm/xe: Change return type of detect_bar2_dgfx() from s64 to u64

[Rodrigo Vivi <rodrigo.vivi@intel.com>]

On Thu, Oct 09, 2025 at 11:02:30PM +0000, Shuicheng Lin wrote:
> The function never returns a negative value, and the return value is
> assigned to a u64 variable. Use u64 for better type correctness
> and clarity.
> 
> v2: add assert to catch theoretical negative or zero stolen size. (Rodrigo)

Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

pushing it to drm-xe-next now...

Thanks for the patches

> 
> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
> Signed-off-by: Shuicheng Lin <shuicheng.lin@intel.com>
> ---
>  drivers/gpu/drm/xe/xe_ttm_stolen_mgr.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_ttm_stolen_mgr.c b/drivers/gpu/drm/xe/xe_ttm_stolen_mgr.c
> index 9b00bdc8ef1a..e368b2a36bac 100644
> --- a/drivers/gpu/drm/xe/xe_ttm_stolen_mgr.c
> +++ b/drivers/gpu/drm/xe/xe_ttm_stolen_mgr.c
> @@ -81,7 +81,7 @@ static u32 get_wopcm_size(struct xe_device *xe)
>  	return wopcm_size;
>  }
>  
> -static s64 detect_bar2_dgfx(struct xe_device *xe, struct xe_ttm_stolen_mgr *mgr)
> +static u64 detect_bar2_dgfx(struct xe_device *xe, struct xe_ttm_stolen_mgr *mgr)
>  {
>  	struct xe_vram_region *tile_vram = xe_device_get_root_tile(xe)->mem.vram;
>  	resource_size_t tile_io_start = xe_vram_region_io_start(tile_vram);
> @@ -105,6 +105,8 @@ static s64 detect_bar2_dgfx(struct xe_device *xe, struct xe_ttm_stolen_mgr *mgr)
>  		return 0;
>  
>  	stolen_size = tile_size - mgr->stolen_base;
> +
> +	xe_assert(xe, stolen_size > wopcm_size);
>  	stolen_size -= wopcm_size;
>  
>  	/* Verify usage fits in the actual resource available */
> -- 
> 2.49.0
>