On Fri, Aug 16, 2019 at 3:05 AM Alexandre Belloni <alexandre.belloni@xxxxxxxxxxx> wrote: > > On 16/08/2019 10:46:36+0800, Biwen Li wrote: > > Issue: > > - # hwclock -w > > hwclock: RTC_SET_TIME: Invalid argument > > > > Why: > > - Relative patch: https://lkml.org/lkml/2019/4/3/55 , this patch > > will always check for unwritable registers, it will compare reg > > with max_register in regmap_writeable. > > > > - In drivers/rtc/rtc-pcf85363.c, CTRL_STOP_EN is 0x2e, but DT_100THS > > is 0, max_regiter is 0x2f, then reg will be equal to 0x30, > > '0x30 < 0x2f' is false,so regmap_writeable will return false. > > > > - Root cause: the buf[] was written to a wrong place in the file > > drivers/rtc/rtc-pcf85363.c > > > > This is not true, the RTC wraps the register accesses properly and this This performance hack probably deserve some explanation in the code comment. :) > is probably something that should be handled by regmap_writable. The address wrapping is specific to this RTC chip. Is it also commonly used by other I2C devices? I'm not sure if regmap_writable should handle the wrapping case if it is too special. Regards, Leo
