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>
diff --git a/arch/arm/mach-mxs/clock-mx28.c b/arch/arm/mach-mxs/clock-mx28.c
index 1ad97fe..5dcc59d 100644
--- a/arch/arm/mach-mxs/clock-mx28.c
+++ b/arch/arm/mach-mxs/clock-mx28.c
@@ -295,11 +295,11 @@
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 @@
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; \