Re: [RFC PATCH 00/15] pwm: add support for atomic update

Uwe Kleine-König
2015-07-02T07:42:43Z

On Thu, Jul 02, 2015 at 10:17:00AM +0300, Tomi Valkeinen wrote:
>
>
> On 02/07/15 10:03, Uwe Kleine-König wrote:
> > Hello Boris,
> >
> > On Wed, Jul 01, 2015 at 10:21:46AM +0200, Boris Brezillon wrote:
> >> This series adds support for atomic PWM update, or ITO, the capability
> >> to update all the parameters of a PWM device (enabled/disabled, period,
> >> duty and polarity) in one go.
> > on first reading the subject of your series I thought it was about
> > asserting that the newly set config is active before the call to
> > pwm_config (et al) returns. That's a problem I addressed a few times in
> > the past. I wonder if it's only me or if a different wording should be
> > used for "update all parameters with a single function call".
>
> In my vocabulary "blocking" means that the work is done before the
> function returns, and "atomic" means the work is done in one step.
blocking is IMHO something slightly different, maybe "synchronous" is a
good term for "done when the call returns".

For write(2) I'd say
- blocking means to only return when the write request has reached the
kernel, but not necessarily the medium. I.e. the caller doesn't need
to care further; and
- atomic means that the contents of two concurrent writers don't mix in
the resulting file content; and
- synchronous means that once write() returns the data is on the
medium.

So atomic seems to be fine to use here.

Best regards
Uwe

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