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clk: rockchip: Make calculations use rounding

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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>
This commit is contained in:
Douglas Anderson 2015-09-30 16:07:38 +02:00 committed by Ulf Hansson
parent f0232063fb
commit 4351f19a33
1 changed files with 7 additions and 6 deletions
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13
drivers/clk/rockchip/clk-mmc-phase.c
View file

@ -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;