From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michael Turquette Subject: Re: [PATCH v2 2/8] clk: rockchip: Make calculations use rounding Date: Thu, 22 Oct 2015 05:04:00 -0700 Message-ID: <20151022120400.20687.61566@quantum> References: <1443622064-14362-1-git-send-email-heiko@sntech.de> <1443622064-14362-3-git-send-email-heiko@sntech.de> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8BIT Return-path: Received: from mail-pa0-f49.google.com ([209.85.220.49]:34577 "EHLO mail-pa0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756803AbbJVMEG convert rfc822-to-8bit (ORCPT ); Thu, 22 Oct 2015 08:04:06 -0400 Received: by padhk11 with SMTP id hk11so85610139pad.1 for ; Thu, 22 Oct 2015 05:04:05 -0700 (PDT) In-Reply-To: <1443622064-14362-3-git-send-email-heiko@sntech.de> Sender: linux-mmc-owner@vger.kernel.org List-Id: linux-mmc@vger.kernel.org To: ulf.hansson@linaro.org, sboyd@codeaurora.org, tgih.jun@samsung.com, jh80.chung@samsung.com Cc: linux-mmc@vger.kernel.org, linux-clk@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-rockchip@lists.infradead.org, dianders@chromium.org, amstan@chromium.org, Heiko Stuebner Quoting Heiko Stuebner (2015-09-30 07:07:38) > 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 Looks good to me. What tree do you want this to go through? Regards, Mike > --- > 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; > -- > 2.5.1 >