mirror of https://gitee.com/openkylin/linux.git
5053037816
m8xx_setup.c says:
/* Force all 8xx processors to use divide by 16 processor clock. */
And at the same time it is using bus-frequency for calculating
timebase. It is okay for most setups because bus-frequency is
equal to clock-frequency.
The problem emerges when cpu frequency is > 66MHz, quoting
u-boot/cpu/mpc8xx/speed.c:
if (gd->cpu_clk <= 66000000) {
sccr_reg |= SCCR_EBDF00; /* bus division factor = 1 */
gd->bus_clk = gd->cpu_clk;
} else {
sccr_reg |= SCCR_EBDF01; /* bus division factor = 2 */
gd->bus_clk = gd->cpu_clk / 2;
}
So in case of cpu clock > 66MHz, bus_clk = cpu_clk / 2. An then, from
Linux, we calculate timebase frequency as tb_freq = bus_clk / 16,
that is cpu_clk / 2 / 16, which is wrong.
This fixes the system time drifting problem on the EP885C board
running at 133MHz.
Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
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| .. | ||
| 8xx | ||
| 40x | ||
| 44x | ||
| 52xx | ||
| 82xx | ||
| 83xx | ||
| 85xx | ||
| 86xx | ||
| 512x | ||
| cell | ||
| celleb | ||
| chrp | ||
| embedded6xx | ||
| iseries | ||
| maple | ||
| pasemi | ||
| powermac | ||
| prep | ||
| ps3 | ||
| pseries | ||
| Kconfig | ||
| Kconfig.cputype | ||
| Makefile | ||
| fsl_uli1575.c | ||