On Thu, Sep 03, 2020 at 09:55:22AM +0200, Bartosz Golaszewski wrote: > On Mon, Aug 31, 2020 at 5:22 AM Kent Gibson <warthog...@gmail.com> wrote: > > > > Add support for edge detection to lines requested using > > GPIO_V2_GET_LINE_IOCTL. > > > > The edge_detector implementation is based on the v1 lineevent > > implementation. > >
[snip] > > + * close in time as possible to the actual event. > > + */ > > + line->timestamp = ktime_get_ns(); > > + > > + if (lr->num_lines != 1) > > + line->req_seqno = atomic_inc_return(&lr->seqno); > > Do we never increase req_seqno for a single line? > For a single line we just use line_seqno for both to avoid the atomic_inc here and so reduce the time spent in the ISR and any SMP sync overheads. As per the comment in struct linereq: * @seqno: the sequence number for edge events generated on all lines in * this line request. Note that this is not used when @num_lines is 1, as * the line_seqno is then the same and is cheaper to calculate. Cheers, Kent.
