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| author | Uwe Kleine-König <u.kleine-koenig@pengutronix.de> | 2011-04-04 16:06:12 +0200 |
|---|---|---|
| committer | Sascha Hauer <s.hauer@pengutronix.de> | 2011-04-12 09:48:02 +0200 |
| commit | f61b9fc27e5b61dbc330696f040cc66ba1dbcbaa (patch) | |
| tree | 96ed9c645dd14f70548601c9717875d651bb27df /arch/arm/mach-mxs | |
| parent | 32a90b6e65792260d6212ac52e8f5be140b6f5be (diff) | |
| download | lwn-f61b9fc27e5b61dbc330696f040cc66ba1dbcbaa.tar.gz lwn-f61b9fc27e5b61dbc330696f040cc66ba1dbcbaa.zip | |
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 <shawn.guo@freescale.com>
LAKML-Reference: 20110225084950.GA13684@S2101-09.ap.freescale.net
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Diffstat (limited to 'arch/arm/mach-mxs')
| -rw-r--r-- | arch/arm/mach-mxs/clock-mx28.c | 7 |
1 files changed, 6 insertions, 1 deletions
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; \ |