Re: select() to /dev/rtc0 to wait for clock tick timed out

[Xiangfu Liu <xiangfu@openmobilefree.net>]

Hi John

Thanks for reply. the patch is not working. I found a work around.
checkout this patch:
  http://projects.qi-hardware.com/index.php/p/openwrt-xburst/source/tree/5a49fe26a5cefe0b1f8dcff1315cf3f2e12bc8f6/target/linux/xburst/patches-3.2/0029-rtc-jz4740-fix-hwclock-give-time-out.patch

after apply this patch. the hwclock worksf ine again. but it is may not a good patch.

Please take a look give me some advice. Thanks John
Xiangfu

On 03/17/2012 09:10 AM, John Stultz wrote:
> On 12/30/2011 12:31 AM, Xiangfu Liu wrote:
>> I meet the same problem on MIPS jz4740, here is the step I try to find out the problem:
>>
>> 1. when I direct run 'hwclock' it will give
>> "select() to /dev/rtc0 to wait for clock tick timed out"
>> attachment 'hwclock.time.out' is the strace log
>>
>> 2. run 'rtctest' program. it works fine. the output is here[1]
>>
>> 3. after 'rtctest', run 'hwclock' again. then it works fine
>> attachment 'hwclock.wors' is the strace log
>>
>> without 'rtctest' run first. 'hwclock' never works.
>> the hwclock works fine in 2.6.27.6, failed under '3.0.0'
>>
>> Please give me some tips how to fix this problem. shoule I modify the driver code
>> or is that relate to 'CONFIG_RTC_INTF_DEV_UIE_EMUL'?
>
> Sorry I missed this email originally, and thank you for pinging me.
>
> Is CONFIG_RTC_INTF_DEV_UIE_EMUL set in the config you're seeing this with? Does disabling it change the behavior?
>
> Just a shot in the dark, but does the following help at all?
> thanks
> -john
>
> Signed-off-by: John Stultz<john.stultz@linaro.org>
>
> diff --git a/drivers/rtc/rtc-jz4740.c b/drivers/rtc/rtc-jz4740.c
>
> index 05ab227..c6c81ba 100644
>
> --- a/drivers/rtc/rtc-jz4740.c
>
> +++ b/drivers/rtc/rtc-jz4740.c
>
> @@ -171,7 +171,8 @@ static int jz4740_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
>
> static int jz4740_rtc_alarm_irq_enable(struct device *dev, unsigned int enable)
>
> {
>
> struct jz4740_rtc *rtc = dev_get_drvdata(dev);
>
> - return jz4740_rtc_ctrl_set_bits(rtc, JZ_RTC_CTRL_AF_IRQ, enable);
>
> + return jz4740_rtc_ctrl_set_bits(rtc,
>
> + JZ_RTC_CTRL_AE |JZ_RTC_CTRL_AF_IRQ, enable);
>
> }
>
>
>
> static struct rtc_class_ops jz4740_rtc_ops = {
>
>
>
>