Hi Alim, On Tuesday 05 July 2016 02:26 PM, Krzysztof Kozlowski wrote: > On 07/05/2016 10:52 AM, Alim Akhtar wrote: >> >> >> On 07/05/2016 01:46 PM, Krzysztof Kozlowski wrote: >>> On 07/04/2016 01:03 PM, Alim Akhtar wrote: >>>> As per code flow it is possible that s3c_rtc_setfreq() might get called >>>> with rtc clock disabled and in set_freq we perform h/w registers >>>> read/write, >>>> which might results in a kernel crash while probing rtc driver. >>>> Below is one such case: >>>> s3c_rtc_probe() >>>> clk_prepare_enable(info->rtc_clk) // rtc clock enabled >>>> s3c_rtc_gettime() // will enable clk if not done, and disable >>>> it upon exit >>>> s3c_rtc_setfreq() //then this will be called with clk disabled >>> >>> The indentation suggests levels of calls (chain) not sequence. This >>> should be: >>> s3c_rtc_probe() >>> clk_prepare_enable(info->rtc_clk) // rtc clock enabled >>> s3c_rtc_gettime() // will enable clk if not done, and disable it >>> upon exit >>> s3c_rtc_setfreq() //then this will be called with clk disabled >>> >>>> >>>> This patch take cares of such issue by adding >>>> s3c_rtc_{enable/disable}_clk in >>>> s3c_rtc_setfreq(). >>> >>> What I don't get is that you wrote "it is *possible* that >>> s3c_rtc_setfreq() *might* get called". From my understanding this will >>> happen always because src_rtc_gettime() always disables the clocks. >>> >>> Why it does not happen always? >>> >> >> Yes, you are right, it is always disabled when reaches s3c_rtc_setfreq(). >> And I observed a kernel crash while testing on exynos7 platform in >> s3c_rtc_setfreq() because clock was always disabled at this point. And >> this patches fixes this issue. > > Ok, thanks! Could you adjust the commit message mentioning that it > always causes crash on Exynos 7 platform and adding: > > Fixes: 24e1455493da ("drivers/rtc/rtc-s3c.c: delete duplicate clock > control") > Cc: <sta...@vger.kernel.org> > > Reviewed-by: Krzysztof Kozlowski <k.kozlow...@samsung.com> >
After addressing Krzysztof's review comments, Please feel free to add Reviewed-by: Pankaj Dubey <pankaj.du...@samsung.com> For testing on Exynos7420 Tested-by: Pankaj Dubey <pankaj.du...@samsung.com> Thanks, Pankaj Dubey > Best regards, > Krzysztof > > -- You received this message because you are subscribed to "rtc-linux". Membership options at http://groups.google.com/group/rtc-linux . Please read http://groups.google.com/group/rtc-linux/web/checklist before submitting a driver. --- You received this message because you are subscribed to the Google Groups "rtc-linux" group. To unsubscribe from this group and stop receiving emails from it, send an email to rtc-linux+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.