Re: [PATCH] drm/amd/display: Correctly initialize some memory in get_available_dsc_slices()

[Hamza Mahfooz]

On 4/25/23 03:53, Christophe JAILLET wrote:
> The intent here is to clear the 'available_slices' buffer before setting
> some values in it.
>
> This is an array of int, so in order to fully initialize it, we must clear
> MIN_AVAILABLE_SLICES_SIZE * sizeof(int) bytes.
>
> Compute the right length of the buffer when calling memset().
>
> Fixes: 97bda0322b8a ("drm/amd/display: Add DSC support for Navi (v2)")
> Signed-off-by: Christophe JAILLET <christophe.jaillet@xxxxxxxxxx>
> ---
> NOT even compile-tested.
>
> make -j7  drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.o
>
> on my setup, it fails with:
>    CC      drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.o
> drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.c:27:10: fatal error: dc_hw_types.h: Aucun fichier ou dossier de ce type
>     27 | #include "dc_hw_types.h"
>        |          ^~~~~~~~~~~~~~~
>
> I've not investigated why.
> ---
>   drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.c b/drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.c
> index b9a05bb025db..1d7384b2be28 100644
> --- a/drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.c
> +++ b/drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.c
> @@ -645,7 +645,7 @@ static int get_available_dsc_slices(union dsc_enc_slice_caps slice_caps, int *av
>   {
>   	int idx = 0;
>   
> -	memset(available_slices, -1, MIN_AVAILABLE_SLICES_SIZE);
> +	memset(available_slices, -1, MIN_AVAILABLE_SLICES_SIZE * sizeof(*available_slices));

Actually, I believe we can drop this memset(). Since,
get_available_dsc_slices() returns the number of indices set, and all of
the users of get_available_dsc_slices() don't cross that bound.

>   
>   	if (slice_caps.bits.NUM_SLICES_1)
>   		available_slices[idx++] = 1;
--
Hamza