On Wed, May 06, 2015 at 04:30:50PM +0000, Opensource [Steve Twiss] wrote: > > On 06 May 2015 17:02 Guenter Roeck wrote: > > > On Wed, May 06, 2015 at 02:54:37PM +0000, Opensource [Steve Twiss] wrote: > > > On 18 April 2015 16:53 Guenter Roeck wrote: > > > > > > Hi Guenter, > > > > > > Thanks for your comments. > > > > > > > On 04/17/2015 07:23 AM, S Twiss wrote: > > > > > From: S Twiss <stwiss.opensource@xxxxxxxxxxx> > > > > > > > > > > Add watchdog driver support for DA9062 > > > > > > > > > > Signed-off-by: Steve Twiss <stwiss.opensource@xxxxxxxxxxx> > > > > > > > > > Hi Steve, > > > > > > > > Key question here is if the da9062 is really so much different to the da9062 > > > > that you can not use the same driver. > > > > > > The DA9062 watchdog driver does have some similarities with the DA9063 watchdog > > > base functionality -- however the watchdog component in the DA9062 chip has more > > > features yet to be added in software. I do intend to add these other features ... > > > however, if "not adding them here" is a problem I can drop the DA9062 watchdog > > > driver from this patch-set until I have time to write in the newer changes. > > > > > > > I am especially concerned about the added da9062_reset_watchdog_timer(), > > > > given the delay it introduces. > > > > > > After giving this some thought, I am going to remove this 300ms delay from the > > > reset_watchdog_timer() function for my next submission attempt. However > > > I am adding a 300ms delay into the stop() and update_timeout_register() functions > > > instead. > > > > > > The DA9062 watchdog ping (register CONTROL_F) is "windowed" for protection > > > against spurious writes -- i.e. the ping function cannot be called within a 250ms > > > time limit or the PMIC will reset. This windowing protection also extends to altering > > > the timeout scale in the CONTROL_D register -- in which case if the timeout > > > register is altered and the ping() function is called within the 250ms limit, the > > > PMIC will reset. The delay is there to stop that from happening. > > > > > > I realised my previous patch was over-sanitised: by putting the time delay into the > > > ping() function I was protecting CONTROL_D in stop() and update_timeout_register(), > > > but I was being too over-protective of the ping() function. Therefore if there was an > > > "incorrect trigger signal", the watchdog would not be allowed to fail because the > > > driver would have filtered out the errors. > > > > > Hi Steve, > > > > From your description, it sounds like the protection is only necessary if there > > was a previous write to the same register(s). If so, it might make sense to > > record the time of such writes, and only add the delay if necessary, and only > > for the remainder of the time. > > > > Would this be possible ? > > > > Hi Guenter, > > I think so -- sounds like it should be possible. > Internally, there are several places where the two registers are written in succession. > Also, I'll have to re-write my tests in several places. > > Probably the best solution would be to defer this watchdog driver for now, and I'll > re-submit it at a later date once the other parts of the DA9062 driver are [hopefully :)] > accepted. That way I can concentrate a solid block of time on the re-testing ... this > is the most time consuming. > Keeping track of the necessary timeout is not mandatory - that was just a thought. If that would hold you up, just ignore the above and keep going. > Is that acceptable to you? -- I don't want to lose your existing comments from your > previous posts, so I will keep track of those changes you have already requested. > Your call, really. I am fine either way. Guenter -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
