From 50086045bd07a9bc55c113f2b19a8f3746c9f9b0 Mon Sep 17 00:00:00 2001 From: Geert Uytterhoeven Date: Fri, 26 Mar 2021 13:00:58 +0100 Subject: [PATCH] clk: renesas: rcar-gen3: Increase Z clock accuracy Improve accuracy in the .determine_rate() callback for Z and Z2 clocks by using rounded divisions. This is similar to the calculation of rates and multipliers in the .recalc_rate() resp. set_rate() callbacks. Sample impact for a few requested clock rates: - R-Car H3: - Z 500 MHz: 468 MHz => 515 MHz - Z2 1000 MHz: 973 MHz => 1011 MHz - R-Car M3-W: - Z 500 MHz: 422 MHz => 516 MHz - Z2 800 MHz: 750 MHz => 788 MHz Signed-off-by: Geert Uytterhoeven Acked-by: Stephen Boyd Reviewed-by: Yoshihiro Shimoda Tested-by: Yoshihiro Shimoda Link: https://lore.kernel.org/r/20210326120100.1577596-6-geert+renesas@glider.be --- drivers/clk/renesas/rcar-gen3-cpg.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/clk/renesas/rcar-gen3-cpg.c b/drivers/clk/renesas/rcar-gen3-cpg.c index a241bf6e904f2..6b389c1caca76 100644 --- a/drivers/clk/renesas/rcar-gen3-cpg.c +++ b/drivers/clk/renesas/rcar-gen3-cpg.c @@ -83,10 +83,10 @@ static int cpg_z_clk_determine_rate(struct clk_hw *hw, if (max_mult < min_mult) return -EINVAL; - mult = div64_ul(req->rate * 32ULL, prate); + mult = DIV_ROUND_CLOSEST_ULL(req->rate * 32ULL, prate); mult = clamp(mult, min_mult, max_mult); - req->rate = div_u64((u64)prate * mult, 32); + req->rate = DIV_ROUND_CLOSEST_ULL((u64)prate * mult, 32); return 0; }