[LinuxPPS] select() on /dev/pps

[Rodolfo Giometti]

On Thu, Jul 30, 2015 at 09:39:27AM +0200, Xavier Bestel wrote:
> Hi,
> 
> for an application of mine I would need to be able to wait for
> events on a char device and on a PPS device; on the char device the
> select() call is the obvious candidate, but it doesn't seem to work
> on the PPS device. That is, select() always returns immediately
> telling some data is available, and a PPS_FETCH either returns
> immediately if flags=0 or waits for 1s if flags=PPS_TIME_INVALID;
> 
> That looks wrong to me. IMHO select() should wait for 1s and
> PPS_FETCH should "consume" the data without waiting.
> If it should work, could you tell me where is my code wrong ?

If I well remember the current implementation of the RFC2783 does not
require to use select() to block until the next timestamp is captured
(see section 3.4.3 - New functions: access to PPS timestamps).

Of course you can feel free to modify the current select() behaviour
and propose a patch! :-)

Ciao,

Rodolfo

-- 

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