Re: [PATCH 2/2] drm/i915/panel: Split range scaling calculation for readiblity

[Jani Nikula <jani.nikula@linux.intel.com>]

On Wed, 14 Feb 2018, Chris Wilson <chris@chris-wilson.co.uk> wrote:
> Split the 64b multiplication from the division so that it doesn't sprawl
> across a couple of lines and use mul_u32_u32() instead of open-coding
> the 64b conversion.
>
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

Reviewed-by: Jani Nikula <jani.nikula@intel.com>


> ---
>  drivers/gpu/drm/i915/intel_panel.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c
> index 41296935ef11..41d00b1603e3 100644
> --- a/drivers/gpu/drm/i915/intel_panel.c
> +++ b/drivers/gpu/drm/i915/intel_panel.c
> @@ -419,8 +419,9 @@ static uint32_t scale(uint32_t source_val,
>  	source_val = clamp(source_val, source_min, source_max);
>  
>  	/* avoid overflows */
> -	target_val = DIV_ROUND_CLOSEST_ULL((uint64_t)(source_val - source_min) *
> -			(target_max - target_min), source_max - source_min);
> +	target_val = mul_u32_u32(source_val - source_min,
> +				 target_max - target_min);
> +	target_val = DIV_ROUND_CLOSEST_ULL(target_val, source_max - source_min);
>  	target_val += target_min;
>  
>  	return target_val;

-- 
Jani Nikula, Intel Open Source Technology Center
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