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

On Thu, Jul 02, 2015 at 10:17:00AM +0300, Tomi Valkeinen wrote:

On 02/07/15 10:03, Uwe Kleine-König wrote:

quoted

Hello Boris,

On Wed, Jul 01, 2015 at 10:21:46AM +0200, Boris Brezillon wrote:

quoted

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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