From: Uwe Kleine-König Date: Mon, 4 Apr 2011 14:06:12 +0000 (+0200) Subject: ARM: mxs/clock-mx28: fix up name##_set_rate X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=f61b9fc27e5b61dbc330696f040cc66ba1dbcbaa;p=linux-beck.git ARM: mxs/clock-mx28: fix up name##_set_rate For the lcdif clock get_rate looks as follows: read div from HW_CLKCTRL_DIS_LCDIF.DIV return clk_get_rate(clk->parent) / div with clk->parent being ref_pix_clk on my system. ref_pix_clk's rate depends on HW_CLKCTRL_FRAC1.PIXFRAC. The set_rate function for lcdif does: parent_rate = clk_get_rate(clk->parent); based on that calculate frac and div such that parent_rate * 18 / frac / div is near the requested rate. HW_CLKCTRL_FRAC1.PIXFRAC is updated with frac HW_CLKCTRL_DIS_LCDIF.DIV is updated with div For this calculation to be correct parent_rate needs to be initialized not with the clock rate of lcdif's parent (i.e. ref_pix) but that of its grandparent (i.e. ref_pix' parent == pll0_clk). The obvious downside of this patch is that now set_rate(lcdif) changes its parent's rate, too. Still this is better than a wrong rate. Acked-by: Shawn Guo LAKML-Reference: 20110225084950.GA13684@S2101-09.ap.freescale.net Signed-off-by: Uwe Kleine-König Signed-off-by: Sascha Hauer --- diff --git a/arch/arm/mach-mxs/clock-mx28.c b/arch/arm/mach-mxs/clock-mx28.c index 1ad97fed1e94..5dcc59d5b9ec 100644 --- a/arch/arm/mach-mxs/clock-mx28.c +++ b/arch/arm/mach-mxs/clock-mx28.c @@ -295,11 +295,11 @@ static int name##_set_rate(struct clk *clk, unsigned long rate) \ unsigned long diff, parent_rate, calc_rate; \ int i; \ \ - parent_rate = clk_get_rate(clk->parent); \ div_max = BM_CLKCTRL_##dr##_DIV >> BP_CLKCTRL_##dr##_DIV; \ bm_busy = BM_CLKCTRL_##dr##_BUSY; \ \ if (clk->parent == &ref_xtal_clk) { \ + parent_rate = clk_get_rate(clk->parent); \ div = DIV_ROUND_UP(parent_rate, rate); \ if (clk == &cpu_clk) { \ div_max = BM_CLKCTRL_CPU_DIV_XTAL >> \ @@ -309,6 +309,11 @@ static int name##_set_rate(struct clk *clk, unsigned long rate) \ if (div == 0 || div > div_max) \ return -EINVAL; \ } else { \ + /* \ + * hack alert: this block modifies clk->parent, too, \ + * so the base to use it the grand parent. \ + */ \ + parent_rate = clk_get_rate(clk->parent->parent); \ rate >>= PARENT_RATE_SHIFT; \ parent_rate >>= PARENT_RATE_SHIFT; \ diff = parent_rate; \