Re: [PATCH 1/2] lib/intel_blt: BB index should be incremented in dwords

["Dixit, Ashutosh" <ashutosh.dixit@intel.com>]

On Mon, 10 Nov 2025 05:58:06 -0800, Balasubramani Vivekanandan wrote:
>
> Size in bytes in used to increment the BB index, which is incorrect.
> Convert bytes to number of dwords.
>
> Signed-off-by: Balasubramani Vivekanandan <balasubramani.vivekanandan@intel.com>
> ---
>  lib/intel_blt.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/lib/intel_blt.c b/lib/intel_blt.c
> index 7f7f5485e..9a0bcb96b 100644
> --- a/lib/intel_blt.c
> +++ b/lib/intel_blt.c
> @@ -1714,7 +1714,7 @@ uint64_t emit_blt_fast_copy(int fd,
>
>	igt_assert(bb_pos + sizeof(data) < blt->bb.size);
>	memcpy(bb + bb_pos, &data, sizeof(data));

What about here?


> -	bb_pos += sizeof(data);
> +	bb_pos += DIV_ROUND_UP(sizeof(data), sizeof(*bb));
>
>	if (emit_bbe) {
>		igt_assert(bb_pos + sizeof(uint32_t) < blt->bb.size);

Here also has:

	bb_pos += sizeof(uint32_t);

And the function is returning bb_pos and can be called multiple times with
the returned bb_pos.

> --
> 2.43.0
>

So there are multiple places where bb_pos is being added to bb. Maybe the
fix should be to just make bb a uint8_t * rather than uint32 * ?