# \[PATCH 4/4\] pwm: omap-dmtimer: add dev\_dbg() message for effective period and duty cycle

- From: Thierry Reding \<hidden\>
- Date: 2016-02-02 16:23:30 
- List: linux-arm-kernel
- Page: https://ratatoskr.run/linux-arm-kernel/2016/02/8728715
- Thread: https://ratatoskr.run/linux-arm-kernel/2016/01/8728537/t.md

```text
On Mon, Feb 01, 2016 at 10:59:52AM -0800, Tony Lindgren wrote:
> Hi,
> 
> * David Rivshin (Allworx) [ref] [160201 10:23]:
> > On Sat, 30 Jan 2016 15:51:06 +0100
> > Neil Armstrong [ref] wrote:
> > 
> > > 2016-01-30 5:26 GMT+01:00 David Rivshin (Allworx)
> > > [ref]:
> > > > From: David Rivshin <redacted>
> > > >
> > > > After going through the math and constraints checking to compute
> > > > load and match values, it is helpful to know what the resultant
> > > > period and duty cycle are.
> > > >
> > > > Signed-off-by: David Rivshin <redacted>
> > > > ---
> > > >
> > > > I found this helpful while testing the other changes, so I included
> > > > it in case it may be of use to someone in the future. I would have
> > > > no issues with dropping this if it's not considered worthwhile.  
> > > 
> > > It's useful, but converting it as a sysfs attribute would be great !
> > 
> > Hrm, yes that is an interesting thought. I imagine that many PWM 
> > devices have similar constraints, so perhaps that would be best 
> > handled generically in the pwm core? Maybe as new optional get_*() 
> > ops, a modification to the config() op to add output params, or just 
> > updating new fields in the struct pwm directly?
> 
> Yeah for /sys entry it should be Linux generic. The other option
> is to use debugfs for driver specific things.

Let's go with debugfs for this one. This is used for diagnostic purposes
and not typically needed when configuring a PWM. While other drivers may
compute similar hardware-specific values, there's nothing generic to
them. The period and duty cycle are the generic input values and those
are already exposed via sysfs.

Thierry
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