From: Chen-Yu Tsai Date: Thu, 15 Sep 2016 15:14:02 +0000 (+0800) Subject: drm/sun4i: dotclock: Round to closest clock rate X-Git-Tag: v4.9.8~1110^2~18^2~3 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=ac412c3d4ff216cb7315cd695be0956ca948aae6;p=platform%2Fkernel%2Flinux-rpi3.git 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 Signed-off-by: Maxime Ripard --- diff --git a/drivers/gpu/drm/sun4i/sun4i_dotclock.c b/drivers/gpu/drm/sun4i/sun4i_dotclock.c index 3eb9978..d401156 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; }