Hi, > On 22/06/2020 07:26:56-0700, Guenter Roeck wrote: > > On Mon, Jun 22, 2020 at 12:14:13PM +0100, Lee Jones wrote: > > > On Mon, 22 Jun 2020, Johnson CH Chen (陳昭勳) wrote: > > > > > > > Dallas/Maxim DS1374 is a counter designed to continuously count > > > > time in seconds. It provides an I2C interface to the host to > > > > access RTC clock or Alarm/Watchdog timer. > > > > > > > > Add MFD Core driver, supporting the I2C communication to RTC and > > > > Watchdog devices. > > > > > > > > Signed-off-by: Johnson Chen <johnsonch.chen@xxxxxxxx> > > > > --- > > > > drivers/mfd/Kconfig | 11 +++++ > > > > drivers/mfd/Makefile | 2 + > > > > drivers/mfd/ds1374.c | 101 > > > > +++++++++++++++++++++++++++++++++++++++++++ > > > > 3 files changed, 114 insertions(+) create mode 100644 > > > > drivers/mfd/ds1374.c > > > > > > Not sure I see the point of this driver. > > > > > > > Not entirely sure either. Seems to me the idea is to use the watchdog > > subsystem for watchdog functionality, but that is just a guess and not > > really necessary (the conversion could be done in the rtc driver). > > I don't think the code as written works - the rtc code uses a mutex > > which the watchdog driver obviously isn't aware of. The mutex would > > have to be moved into the mfd code, with respective access functions. > > > > Overall this adds a lot of complexity, and it seems the > > interdependencies between rtc and watchdog functionality are not well > > understood. Plus, other watchdog drivers have recently been added to > > other rtc clock chips, so this adds some inconsistencies in the rtc > > subsystem. Are we going to see this change for all those combined > rtc/watchdog drivers ? > > If so, it might make sense to communicate that now to ensure consistency. > > > > I read the datasheet again and I agree the watchdog part can live in the rtc > driver. As only the RTC alarm and the watchdog are mutually exclusive. I don't > think an MFD driver is necessary. Converting the current driver to the > watchdog subsystem seems to be the correct way forward. > Thanks for your good thinking. If we want to add watchdog function such as "nowayout" to the driver, it's good to try to upstream this in rtc-ds1374.c in rtc subsystem? It seems like more complexity if we want to separate rtc and watchdog for one chip supports. For one chip which supports rtc/alarm and watchdog, can we upstream rtc/alarm and watchdog functions to these driver no matter where it's in rtc or watchdog subsystem? > -- > Alexandre Belloni, Bootlin > Embedded Linux and Kernel engineering > https://bootlin.com Best regards, Johnson
