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Re: [PATCH 3/4] watchdog: sa11x0/pxa: get rid of get_clock_tick_rate

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Guenter Roeck <linux@roeck-us.net> writes:

> On 09/19/2016 03:36 PM, Russell King - ARM Linux wrote:
>> On Mon, Sep 19, 2016 at 01:08:16PM -0700, Guenter Roeck wrote:
>>> On Mon, Sep 19, 2016 at 09:12:14PM +0200, Robert Jarzmik wrote:
>>>> The OS timer rate used for the watchdog can now be fetched from the
>>>> standard clock API. This will remove the last user of
>>>> get_clock_tick_rate() in both pxa and sa11x0 architectures.
>>>>
>>>> Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
>>>
>>> Did you test this ? Potential problem, if built into the kernel, could be that
>>> the clocks might not be ready by the time the driver is instantiated. Unless
>>> this is converted to a platform driver, it won't be able to handle a
>>> -EPROBE_DEFER from the clock subsystem.
>>
>> Really not a problem at all.  The OSTIMER0 is required for the system
>> tick, and if that's not present, the kernel will be without any kind
>> of time keeping, so a missing watchdog driver is the least of the
>> problems.
>>
>> Therefore, both PXA and SA11x0 register their clocks really early to
>> ensure that OSTIMER0 is available by the time_init() stage, which is
>> way before driver probe time.
>>
>
> You are right. And, at least in qemu, it actually works.
Hi Guenter,

Yes, it was tested on pxa25x (lubbock) and pxa27x (mainstone).

Cheers.

-- 
Robert

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Thread

[PATCH 0/4] kill get_clock_tick_rate() Robert Jarzmik <robert.jarzmik@free.fr> - 2016-09-19 21:20 +0200
  [PATCH 2/4] ARM: sa11x0/pxa: acquire timer rate from the clock rate Robert Jarzmik <robert.jarzmik@free.fr> - 2016-09-19 21:20 +0200
    Re: [PATCH 2/4] ARM: sa11x0/pxa: acquire timer rate from the clock  rate Daniel Lezcano <daniel.lezcano@linaro.org> - 2016-09-19 21:50 +0200
  [PATCH 1/4] clk: pxa25x: OSTIMER0 clocks from the main oscillator Robert Jarzmik <robert.jarzmik@free.fr> - 2016-09-19 21:20 +0200
    Re: [PATCH 1/4] clk: pxa25x: OSTIMER0 clocks from the main oscillator Stephen Boyd <sboyd@codeaurora.org> - 2016-09-19 21:30 +0200
  [PATCH 3/4] watchdog: sa11x0/pxa: get rid of get_clock_tick_rate Robert Jarzmik <robert.jarzmik@free.fr> - 2016-09-19 21:30 +0200
    Re: [PATCH 3/4] watchdog: sa11x0/pxa: get rid of get_clock_tick_rate Guenter Roeck <linux@roeck-us.net> - 2016-09-19 22:10 +0200
      Re: [PATCH 3/4] watchdog: sa11x0/pxa: get rid of get_clock_tick_rate Russell King - ARM Linux <linux@armlinux.org.uk> - 2016-09-20 00:40 +0200
        Re: [PATCH 3/4] watchdog: sa11x0/pxa: get rid of get_clock_tick_rate Guenter Roeck <linux@roeck-us.net> - 2016-09-20 06:40 +0200
          Re: [PATCH 3/4] watchdog: sa11x0/pxa: get rid of get_clock_tick_rate Robert Jarzmik <robert.jarzmik@free.fr> - 2016-09-20 08:20 +0200
    Re: [PATCH 3/4] watchdog: sa11x0/pxa: get rid of get_clock_tick_rate Guenter Roeck <linux@roeck-us.net> - 2016-09-20 06:40 +0200
  [PATCH 4/4] ARM: sa11x0/pxa: get rid of get_clock_tick_rate Robert Jarzmik <robert.jarzmik@free.fr> - 2016-09-19 21:30 +0200
    Re: [PATCH 4/4] ARM: sa11x0/pxa: get rid of get_clock_tick_rate Daniel Lezcano <daniel.lezcano@linaro.org> - 2016-09-19 22:00 +0200

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