RE: [PATCH 1/3] pwm: Add count attribute in sysfs for Intel Keem Bay

["G Jaya Kumaran, Vineetha" <vineetha.g.jaya.kumaran@intel.com>]

> -----Original Message-----
> From: linux-pwm-owner@vger.kernel.org <linux-pwm-owner@vger.kernel.org>
> On Behalf Of Uwe Kleine-König
> Sent: Sunday, May 24, 2020 5:05 AM
> To: G Jaya Kumaran, Vineetha <vineetha.g.jaya.kumaran@intel.com>
> Cc: thierry.reding@gmail.com; robh+dt@kernel.org; linux-
> pwm@vger.kernel.org; devicetree@vger.kernel.org; Wan Mohamad, Wan
> Ahmad Zainie <wan.ahmad.zainie.wan.mohamad@intel.com>; Shevchenko,
> Andriy <andriy.shevchenko@intel.com>
> Subject: Re: [PATCH 1/3] pwm: Add count attribute in sysfs for Intel Keem Bay
> 
> On Sun, May 17, 2020 at 09:52:38PM +0800,
> vineetha.g.jaya.kumaran@intel.com wrote:
> > From: "Lai, Poey Seng" <poey.seng.lai@intel.com>
> >
> > In Keem Bay, the number of repetitions for the period/waveform can be
> > configured from userspace. This requires addition of a sysfs attribute
> > to get/set the repetition count. Setting this value to 0 will result
> > in continuous repetition of the waveform until the channel is disabled
> > or reconfigured.
> 
> There is nothing specific for Keem Bay in this patch, the only special thing here is
> that this driver is the first implementor.
> 
> IMHO all drivers that don't support count should be changed to fail if a count > 0
> is passed and introducing support in the sysfs interface should be a separate
> change.
> 
> Having said that I'm not convinced this is a good idea given that only very few
> driver can support this interface. Also this needs documentation, e.g. what is
> expected from .get_state().
> 
> You should also motivate what this functionality is used for in the commit log
> and I'd prefer to see an in-tree user (apart from sysfs which I don't count as
> such).
> 

Agreed, the wording used here is not accurate as this is not specific for Keem Bay.
Before submitting v2, I will cross-check about the use-case for this functionality, and if it 
can be implemented in some other less intrusive way to the framework (perhaps via a DT property?)

> Best regards
> Uwe
> 
> --
> Pengutronix e.K.                           | Uwe Kleine-König            |
> Industrial Linux Solutions                 | https://www.pengutronix.de/ |