clk: rockchip: Make calculations use rounding
From: Douglas Anderson <dianders@...> Date: Mon, 31 Aug 2015 20:24:00 +0200
Commit-Message
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@...> Signed-off-by: Heiko Stuebner <heiko@...>
Patch-Comment
drivers/clk/rockchip/clk-mmc-phase.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-)
Statistics
- 7 lines added
- 6 lines removed
Changes
--------------------- drivers/clk/rockchip/clk-mmc-phase.c ---------------------
index a797d86..bc24e5a 100644
@@ -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 += 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;
+ 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 = 10000000; /* PSECS_PER_SEC / 10000 / 10 */
delay *= remainder;
+ delay = DIV_ROUND_CLOSEST(delay,
+ (rate / 1000) * 36 *
+ (ROCKCHIP_MMC_DELAY_ELEMENT_PSEC / 10));
+ 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;