drm/i915/panel: Split range scaling calculation for readiblity

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>
Link: https://patchwork.freedesktop.org/patch/msgid/20180214091747.12753-2-chris@chris-wilson.co.uk

diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c
index 4129693..41d00b1 100644 (file)
--- 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;