MyungJoo Ham wrote: > > On Wed, Oct 27, 2010 at 4:58 PM, Kukjin Kim <kgene.kim@xxxxxxxxxxx> wrote: > > MyungJoo Ham wrote: > >> > >> On Fri, Oct 8, 2010 at 8:41 AM, Kukjin Kim <kgene.kim@xxxxxxxxxxx> wrote: > >> > From: Changhwan Youn <chaos.youn@xxxxxxxxxxx> > >> > > >> > S3C2410_RTCCON of TYPE_S3C64XX RTC should be read/written by > >> > readw and writew, because TYPE_S3C64XX RTC uses bit 8 and 9. > >> > And TYPE_S3C2410 RTC also can access it by readw and writew. > >> > > >> > Signed-off-by: Changhwan Youn <chaos.youn@xxxxxxxxxxx> > >> > [atul.dahiya@xxxxxxxxxxx: tested on smdk2416] > >> > Tested-by: Atul Dahiya <atul.dahiya@xxxxxxxxxxx> > >> > Signed-off-by: Kukjin Kim <kgene.kim@xxxxxxxxxxx> > >> > Cc: Ben Dooks <ben-linux@xxxxxxxxx> > >> > --- > >> > drivers/rtc/rtc-s3c.c | 36 ++++++++++++++++++------------------ > >> > 1 files changed, 18 insertions(+), 18 deletions(-) > >> > >> Hello, > >> > > Hi, > >> > >> Sorry for a late reply... > >> > > Yeah, too late :-( > > > >> Anyway, I have a small question in this rtc-s3c.c driver. > >> > >> Is there any reason to use read/write b/w to access registers of rtc-s3c? > >> > > See the git comment. > > > >> Why don't we use readl/writel when accessing registers in this drivers > > > > I don't know why we should use readl/writel for all case... > > even though we can use just word or byte access. > > > >> and just forget which registers require at least 8 or 16 or 32 bits? > >> > >> In fact, it appears that readw/writew accesses 16bits, not 32bits in > > > > Yes... > > > >> ARM machines, which may incur problems with TICCNT(S3C2410_TICNT in the > code)/CURTICCNT > >> registers. > >> > > I can't get your comment... > > It is because TICCNT and CURTICCNT RTC registers of S5PC210 require > 32bit access according to the manual while this patch still uses 16bit > accesses for them. > > Besides, ALMYEAR/BCDYEAR(S3C2410_RTCYEAR) requires at least 16bit access. > > > This issue was found today while testing suspend-to-mem with s5pc210 > and rtc-wakeup loop. My guess is that saving and restoring only 8 bits > of TICNT at suspend/resume function incurred the instable > suspend-to-mem (kernel hangs with about 1/100 probability) Using > readl/writel for TICNT solved the kernel hang issue. > I got it. You mean need to fix readb(TICNT) of s3c_rtc_suspend() and s3c_rtc_resume()... Ok...but it's different some kind of bug fix with this patch. And...need to check side effect to all of Samsung SoCs. Hmm...and first of all, not supported S5PV310/S5PC210 PM in mainline now. Anyway if any bug, we can fix it during -rc. I always welcome to bug fix to our codes. :-) Thanks. Best regards, Kgene. -- Kukjin Kim <kgene.kim@xxxxxxxxxxx>, Senior Engineer, SW Solution Development Team, Samsung Electronics Co., Ltd. -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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