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    SubjectRE: [PATCH V1 5/6] watchdog: da9062: DA9062 watchdog driver
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    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@diasemi.com>
    > > > >
    > > > > Add watchdog driver support for DA9062
    > > > >
    > > > > Signed-off-by: Steve Twiss <stwiss.opensource@diasemi.com>
    > > > >
    > > > 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.

    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.

    Regards,
    Steve


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