Hi, On Wed, Feb 15, 2012 at 1:11 PM, Tomi Valkeinen <tomi.valkeinen@xxxxxx> wrote: > On Wed, 2012-02-15 at 11:20 +0530, mythripk@xxxxxx wrote: >> From: Mythri P K <mythripk@xxxxxx> >> >> Add M2 divider in the equation to calculate regm and regmf. >> Formula for calculating: >> Output clock on digital core domain: >> CLKOUT = (M / (N+1))*CLKINP*(1/M2) >> Internal oscillator output clock on internal LDO domain: >> CLKDCOLDO = (M / (N+1))*CLKINP >> The current code when allows variable M2 values as input >> ignores using M2 divider values in calculation of regm and regmf. >> so fix it by using M2 in calculation although the default value for >> M2 is 1. >> >> Signed-off-by: Mythri P K <mythripk@xxxxxx> >> --- >> drivers/video/omap2/dss/hdmi.c | 16 ++++++++-------- >> 1 files changed, 8 insertions(+), 8 deletions(-) >> >> diff --git a/drivers/video/omap2/dss/hdmi.c b/drivers/video/omap2/dss/hdmi.c >> index 92a6679..9185630 100644 >> --- a/drivers/video/omap2/dss/hdmi.c >> +++ b/drivers/video/omap2/dss/hdmi.c >> @@ -256,24 +256,24 @@ static void hdmi_compute_pll(struct omap_dss_device *dssdev, int phy, >> >> refclk = clkin / pi->regn; >> >> - /* >> - * multiplier is pixel_clk/ref_clk >> - * Multiplying by 100 to avoid fractional part removal >> - */ >> - pi->regm = (phy * 100 / (refclk)) / 100; >> - >> if (dssdev->clocks.hdmi.regm2 == 0) >> pi->regm2 = HDMI_DEFAULT_REGM2; >> else >> pi->regm2 = dssdev->clocks.hdmi.regm2; >> >> /* >> + * multiplier is pixel_clk/ref_clk >> + * Multiplying by 100 to avoid fractional part removal >> + */ >> + pi->regm = (phy * 100 * pi->regm2 / (refclk)) / 100; > > No need for parenthesis around refclk. Well this is just a copy of old code will change. > >> + >> + /* >> * fractional multiplier is remainder of the difference between >> * multiplier and actual phy(required pixel clock thus should be >> * multiplied by 2^18(262144) divided by the reference clock >> */ >> - mf = (phy - pi->regm * refclk) * 262144; >> - pi->regmf = mf / (refclk); >> + mf = (phy - pi->regm / pi->regm2 * refclk) * 262144; > > What kind of values does regm have? If the regm2 is something else than > 1, and regm is relatively small value, it's quite easy to lose precision > there. Would it be better to have: Normally regm values are much higher compared to regm2 , regm2 is normally 1 or 2. also given that regm2 is a multiplier factor in calculating regm there should not be any precision factor what do you think ? Thanks and regards, Mythri. > > pi->regm * refclk / pi->regm2 > > Tomi > -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
