Re: [PATCH v2] drm/dsc: Return unsigned long on compute offset

[Jani Nikula <jani.nikula-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>]

On Fri, 22 Nov 2019, <mikita.lipski@amd.com> wrote:
> From: Mikita Lipski <mikita.lipski@amd.com>
>
> We shouldn't compare int with unsigned long to find the max value
> and since we are not expecting negative value returned from
> compute_offset we should make this function return unsigned long
> so we can compare the values when computing rc parameters.
>
> v2: Modified function parameters to unsigned type for type
> consistency

I don't think that really addresses the review.

But all the same, current drm-tip does not have a compute_offset()
function, and the only reference to it in my email are your patches, so
this is completely unactionable anyway.

In any case I think the root cause for your issues is the unfounded use
of unsigned longs in drm_dsc_compute_rc_parameters(). Fix that and many
of your problems go away.

BR,
Jani.

>
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Cc: Nikola Cornij <nikola.cornij@amd.com>
> Cc: Harry Wentland <harry.wentland@amd.com>
> Signed-off-by: Mikita Lipski <mikita.lipski@amd.com>
> ---
>  drivers/gpu/drm/drm_dsc.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_dsc.c b/drivers/gpu/drm/drm_dsc.c
> index 74f3527f567d..ccce0297da64 100644
> --- a/drivers/gpu/drm/drm_dsc.c
> +++ b/drivers/gpu/drm/drm_dsc.c
> @@ -245,11 +245,11 @@ void drm_dsc_pps_payload_pack(struct drm_dsc_picture_parameter_set *pps_payload,
>  }
>  EXPORT_SYMBOL(drm_dsc_pps_payload_pack);
>  
> -static int compute_offset(struct drm_dsc_config *vdsc_cfg, int pixels_per_group,
> -				int groups_per_line, int grpcnt)
> +static unsigned long compute_offset(struct drm_dsc_config *vdsc_cfg, unsigned int pixels_per_group,
> +				unsigned long groups_per_line, unsigned long grpcnt)
>  {
> -	int offset = 0;
> -	int grpcnt_id = DIV_ROUND_UP(vdsc_cfg->initial_xmit_delay, pixels_per_group);
> +	unsigned long offset = 0;
> +	unsigned long grpcnt_id = DIV_ROUND_UP(vdsc_cfg->initial_xmit_delay, pixels_per_group);
>  
>  	if (grpcnt <= grpcnt_id)
>  		offset = DIV_ROUND_UP(grpcnt * pixels_per_group * vdsc_cfg->bits_per_pixel, 16);

-- 
Jani Nikula, Intel Open Source Graphics Center
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