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authorDouglas Anderson <dianders@chromium.org>2015-09-30 16:07:38 +0200
committerUlf Hansson <ulf.hansson@linaro.org>2015-10-26 16:00:07 +0100
commit4351f19a337d48a780762d076408ebe9b0c1f945 (patch)
tree903abc321be44907394e9d399066126c2f0db5de /drivers/clk
parentf0232063fb64fc79bfb7b6b35d611b2e4a79ffe6 (diff)
downloadlinux-4351f19a337d48a780762d076408ebe9b0c1f945.tar.bz2
clk: rockchip: Make calculations use rounding
Let's use DIV_ROUND_CLOSEST for rounding, not just truncating division. This lets us get closer to the right rate. Before this: set_phase(86) delay_nums=26 reg[0xf000420c]=0x468 actual_degrees=83 set_phase(89) delay_nums=27 reg[0xf000420c]=0x46c actual_degrees=86 After this: set_phase(86) delay_nums=27 reg[0xf000420c]=0x46c actual_degrees=86 set_phase(89) delay_nums=28 reg[0xf000420c]=0x470 actual_degrees=90 Signed-off-by: Douglas Anderson <dianders@chromium.org> Signed-off-by: Heiko Stuebner <heiko@sntech.de> Acked-by: Stephen Boyd <sboyd@codeaurora.org> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Diffstat (limited to 'drivers/clk')
-rw-r--r--drivers/clk/rockchip/clk-mmc-phase.c13
1 files changed, 7 insertions, 6 deletions
diff --git a/drivers/clk/rockchip/clk-mmc-phase.c b/drivers/clk/rockchip/clk-mmc-phase.c
index a797d8625f6d..bc24e5a002e7 100644
--- a/drivers/clk/rockchip/clk-mmc-phase.c
+++ b/drivers/clk/rockchip/clk-mmc-phase.c
@@ -69,7 +69,7 @@ static int rockchip_mmc_get_phase(struct clk_hw *hw)
delay_num = (raw_value & ROCKCHIP_MMC_DELAYNUM_MASK);
delay_num >>= ROCKCHIP_MMC_DELAYNUM_OFFSET;
- degrees += delay_num * factor / 10000;
+ degrees += DIV_ROUND_CLOSEST(delay_num * factor, 10000);
}
return degrees % 360;
@@ -82,7 +82,7 @@ static int rockchip_mmc_set_phase(struct clk_hw *hw, int degrees)
u8 nineties, remainder;
u8 delay_num;
u32 raw_value;
- u64 delay;
+ u32 delay;
nineties = degrees / 90;
remainder = (degrees % 90);
@@ -110,12 +110,13 @@ static int rockchip_mmc_set_phase(struct clk_hw *hw, int degrees)
* Convert to delay; do a little extra work to make sure we
* don't overflow 32-bit / 64-bit numbers.
*/
- delay = PSECS_PER_SEC;
+ delay = 10000000; /* PSECS_PER_SEC / 10000 / 10 */
delay *= remainder;
- do_div(delay, 10000);
- do_div(delay, (rate / 1000) * 36 * ROCKCHIP_MMC_DELAY_ELEMENT_PSEC);
+ delay = DIV_ROUND_CLOSEST(delay,
+ (rate / 1000) * 36 *
+ (ROCKCHIP_MMC_DELAY_ELEMENT_PSEC / 10));
- delay_num = (u8) min(delay, 255ULL);
+ delay_num = (u8) min_t(u32, delay, 255);
raw_value = delay_num ? ROCKCHIP_MMC_DELAY_SEL : 0;
raw_value |= delay_num << ROCKCHIP_MMC_DELAYNUM_OFFSET;