From mboxrd@z Thu Jan 1 00:00:00 1970 From: heiko@sntech.de (Heiko Stuebner) Date: Mon, 31 Aug 2015 20:24:00 +0200 Subject: [PATCH 2/8] clk: rockchip: Make calculations use rounding In-Reply-To: <1441045446-30858-1-git-send-email-heiko@sntech.de> References: <1441045446-30858-1-git-send-email-heiko@sntech.de> Message-ID: <1441045446-30858-3-git-send-email-heiko@sntech.de> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org From: Douglas Anderson 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 Signed-off-by: Heiko Stuebner --- drivers/clk/rockchip/clk-mmc-phase.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/drivers/clk/rockchip/clk-mmc-phase.c b/drivers/clk/rockchip/clk-mmc-phase.c index a797d86..bc24e5a 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; -- 2.1.4