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authorChen-Yu Tsai <wens@csie.org>2016-09-15 18:14:02 +0300
committerMaxime Ripard <maxime.ripard@free-electrons.com>2016-09-20 10:19:31 +0300
commitac412c3d4ff216cb7315cd695be0956ca948aae6 (patch)
tree59fc213ae99c9e6e68e10b356d95bbd88ca5916f /drivers/gpu/drm/sun4i/sun4i_dotclock.c
parent15ae0ea4bf4395c5ba7a3242138a528bd3dfbb14 (diff)
downloadlinux-ac412c3d4ff216cb7315cd695be0956ca948aae6.tar.xz
drm/sun4i: dotclock: Round to closest clock rate
With display pixel clocks we want to have the closest possible clock rate, to minimize timing and refresh rate skews. Whether the actual clock rate is higher or lower than the requested rate is less important. Also check candidates against the requested rate, rather than the ideal parent rate, the varying dividers also influence the difference between the requested rate and the rounded rate. Signed-off-by: Chen-Yu Tsai <wens@csie.org> Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Diffstat (limited to 'drivers/gpu/drm/sun4i/sun4i_dotclock.c')
-rw-r--r--drivers/gpu/drm/sun4i/sun4i_dotclock.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/gpu/drm/sun4i/sun4i_dotclock.c b/drivers/gpu/drm/sun4i/sun4i_dotclock.c
index 3eb99784f371..d401156490f3 100644
--- a/drivers/gpu/drm/sun4i/sun4i_dotclock.c
+++ b/drivers/gpu/drm/sun4i/sun4i_dotclock.c
@@ -90,7 +90,8 @@ static long sun4i_dclk_round_rate(struct clk_hw *hw, unsigned long rate,
goto out;
}
- if ((rounded < ideal) && (rounded > best_parent)) {
+ if (abs(rate - rounded / i) <
+ abs(rate - best_parent / best_div)) {
best_parent = rounded;
best_div = i;
}