Re: [PATCH] clk: Add PWM clock driver

Re: [PATCH] clk: Add PWM clock driver

[Janusz Użycki]

Hi,

http://patchwork.ozlabs.org/patch/359069/
https://lkml.org/lkml/2014/6/12/186

Will the patch ever included to linux-next?

pwm_config()  API could be extended to support
not only period [ns] and duty [ns] time
but also frequency [Hz] and duty cycle fraction [1/1000?]
(instead of time in ns) as parameters.
Then  ns (rounded by pwm) to freq. conversion problem
inclk_pwm_recalc_rate() usingpwm_get_period()
could be avoided.
To extend the API pwm_config() can support
new flags forduty_ns and period_ns,
eg. PWM_DUTY_PERCENT and PWM_PERIOD_HZ.


best regards
Janusz

Re: [PATCH] clk: Add PWM clock driver

[Thierry Reding]

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On Wed, Sep 10, 2014 at 10:05:17PM +0200, Janusz Użycki wrote:
> Hi,
> 
> http://patchwork.ozlabs.org/patch/359069/
> https://lkml.org/lkml/2014/6/12/186
> 
> Will the patch ever included to linux-next?

I've never seen this patch before. From a quick look it doesn't seem
like it would work as is, but the idea is certainly interesting. If
somebody decides to continue work on it, please Cc me and the linux-pwm
mailing list.

> pwm_config()  API could be extended to support
> not only period [ns] and duty [ns] time
> but also frequency [Hz] and duty cycle fraction [1/1000?]
> (instead of time in ns) as parameters.
> Then  ns (rounded by pwm) to freq. conversion problem
> inclk_pwm_recalc_rate() usingpwm_get_period()
> could be avoided.
> To extend the API pwm_config() can support
> new flags forduty_ns and period_ns,
> eg. PWM_DUTY_PERCENT and PWM_PERIOD_HZ.

Is that rounding really a problem? Also the PWM chips will most likely
use the concept of period and duty-cycle internally anyway, so it will
convert back from Hz/percentage to nanoseconds and fall victim to
similar rounding effects.

Thierry

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Re: [PATCH] clk: Add PWM clock driver

[Mike Turquette]

Quoting Thierry Reding (2014-09-23 01:51:31)
> On Wed, Sep 10, 2014 at 10:05:17PM +0200, Janusz Użycki wrote:
> > Hi,
> > 
> > http://patchwork.ozlabs.org/patch/359069/
> > https://lkml.org/lkml/2014/6/12/186
> > 
> > Will the patch ever included to linux-next?
> 
> I've never seen this patch before. From a quick look it doesn't seem
> like it would work as is, but the idea is certainly interesting. If
> somebody decides to continue work on it, please Cc me and the linux-pwm
> mailing list.

I just merged a gpio-controlled clock gate and I'm fine with a PWM clock
output.

Janusz, how are you testing the clock driver?

Regards,
Mike

> 
> > pwm_config()  API could be extended to support
> > not only period [ns] and duty [ns] time
> > but also frequency [Hz] and duty cycle fraction [1/1000?]
> > (instead of time in ns) as parameters.
> > Then  ns (rounded by pwm) to freq. conversion problem
> > inclk_pwm_recalc_rate() usingpwm_get_period()
> > could be avoided.
> > To extend the API pwm_config() can support
> > new flags forduty_ns and period_ns,
> > eg. PWM_DUTY_PERCENT and PWM_PERIOD_HZ.
> 
> Is that rounding really a problem? Also the PWM chips will most likely
> use the concept of period and duty-cycle internally anyway, so it will
> convert back from Hz/percentage to nanoseconds and fall victim to
> similar rounding effects.
> 
> Thierry

Re: [PATCH] clk: Add PWM clock driver

[Janusz Użycki]

W dniu 2014-09-27 o 22:01, Mike Turquette pisze:
> Quoting Thierry Reding (2014-09-23 01:51:31)
>> On Wed, Sep 10, 2014 at 10:05:17PM +0200, Janusz Użycki wrote:
>>> Hi,
>>>
>>> http://patchwork.ozlabs.org/patch/359069/
>>> https://lkml.org/lkml/2014/6/12/186
>>>
>>> Will the patch ever included to linux-next?
>> I've never seen this patch before. From a quick look it doesn't seem
>> like it would work as is, but the idea is certainly interesting. If
>> somebody decides to continue work on it, please Cc me and the linux-pwm
>> mailing list.
> I just merged a gpio-controlled clock gate and I'm fine with a PWM clock
> output.
>
> Janusz, how are you testing the clock driver?

Sorry, I didn't noticed the email.
I didn't test the patch yet. However I plan to check it this year.

best regards
Janusz

>
> Regards,
> Mike
>
>>> pwm_config()  API could be extended to support
>>> not only period [ns] and duty [ns] time
>>> but also frequency [Hz] and duty cycle fraction [1/1000?]
>>> (instead of time in ns) as parameters.
>>> Then  ns (rounded by pwm) to freq. conversion problem
>>> inclk_pwm_recalc_rate() usingpwm_get_period()
>>> could be avoided.
>>> To extend the API pwm_config() can support
>>> new flags forduty_ns and period_ns,
>>> eg. PWM_DUTY_PERCENT and PWM_PERIOD_HZ.
>> Is that rounding really a problem? Also the PWM chips will most likely
>> use the concept of period and duty-cycle internally anyway, so it will
>> convert back from Hz/percentage to nanoseconds and fall victim to
>> similar rounding effects.
>>
>> Thierry
>

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Re: [PATCH] clk: Add PWM clock driver

[Philipp Zabel]

Am Samstag, den 27.09.2014, 13:01 -0700 schrieb Mike Turquette:
> Quoting Thierry Reding (2014-09-23 01:51:31)
> > On Wed, Sep 10, 2014 at 10:05:17PM +0200, Janusz Użycki wrote:
> > > Hi,
> > > 
> > > http://patchwork.ozlabs.org/patch/359069/
> > > https://lkml.org/lkml/2014/6/12/186
> > > 
> > > Will the patch ever included to linux-next?
> > 
> > I've never seen this patch before. From a quick look it doesn't seem
> > like it would work as is, but the idea is certainly interesting. If
> > somebody decides to continue work on it, please Cc me and the linux-pwm
> > mailing list.
> 
> I just merged a gpio-controlled clock gate and I'm fine with a PWM clock
> output.
> 
> Janusz, how are you testing the clock driver?

On the BoundaryDevices Nitrogen6X board, the master clock to the OV5640
MIPI CSI-2 sensor module has to be provided by a PWM.

regards
Philipp