drm/i915: Simplify SWIDTHSW calculation
The formula in Bspec for computing the overlay SWIDTHSW is overly
obfuscated. Simplify the formula to something that's easily parsed by
humans.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1481131693-27993-8-git-send-email-ville.syrjala@linux.intel.com
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
diff --git a/drivers/gpu/drm/i915/intel_overlay.c b/drivers/gpu/drm/i915/intel_overlay.c
index 935e6bc..9be9522 100644
--- a/drivers/gpu/drm/i915/intel_overlay.c
+++ b/drivers/gpu/drm/i915/intel_overlay.c
@@ -567,19 +567,17 @@ static int uv_vsubsampling(u32 format)
static u32 calc_swidthsw(struct drm_i915_private *dev_priv, u32 offset, u32 width)
{
- u32 mask, shift, ret;
- if (IS_GEN2(dev_priv)) {
- mask = 0x1f;
- shift = 5;
- } else {
- mask = 0x3f;
- shift = 6;
- }
- ret = ((offset + width + mask) >> shift) - (offset >> shift);
- if (!IS_GEN2(dev_priv))
- ret <<= 1;
- ret -= 1;
- return ret << 2;
+ u32 sw;
+
+ if (IS_GEN2(dev_priv))
+ sw = ALIGN((offset & 31) + width, 32);
+ else
+ sw = ALIGN((offset & 63) + width, 64);
+
+ if (sw == 0)
+ return 0;
+
+ return (sw - 32) >> 3;
}
static const u16 y_static_hcoeffs[N_HORIZ_Y_TAPS * N_PHASES] = {