On Mon, 8 Mar 2021 10:07:05 +0000 "Sa, Nuno" <Nuno.Sa@xxxxxxxxxx> wrote: > > -----Original Message----- > > From: Jonathan Cameron <jic23@xxxxxxxxxx> > > Sent: Saturday, March 6, 2021 6:35 PM > > To: Hennerich, Michael <Michael.Hennerich@xxxxxxxxxx> > > Cc: zzzzArdelean, zzzzAlexandru <alexandru.Ardelean@xxxxxxxxxx>; > > linux-kernel@xxxxxxxxxxxxxxx; linux-iio@xxxxxxxxxxxxxxx; > > lars@xxxxxxxxxx; Sa, Nuno <Nuno.Sa@xxxxxxxxxx>; Bogdan, Dragos > > <Dragos.Bogdan@xxxxxxxxxx> > > Subject: Re: [PATCH v3 0/6] iio: Add output buffer support > > > > On Fri, 5 Mar 2021 08:57:08 +0000 > > "Hennerich, Michael" <Michael.Hennerich@xxxxxxxxxx> wrote: > > > > > Hi Jonathan and others, > > > > > > With output/dac buffer support the semantics of the scan_element > > type may change. > > > > > > Today the Format is [be|le]:[s|u]bits/storagebitsXrepeat[>>shift]. > > > > > > While shift (if specified) is the shift that needs to be applied prior to > > masking out unused bits. > > > > > > So far so good and it sounds universal. > > > > > > However, we use the right shift (operator) for that, which makes > > sense for capture devices. > > > For output devices the more logical operator would be the left shift. > > > > > > I'm not proposing a new Format here. I just want to get some > > agreement that for an output device > > > > > > le:s12/16>>4 > > > > > > is understood as a left shift of 4, since the unused bits are then on > > the LSB. > > > > Good question. Guess I wasn't thinking ahead when I came up with > > that :) > > > > I'm not sure I'd mind if we did decide to define a new format for > > output > > buffers. Feels like it should be easy to do. > > > > What do others think? > > > > I guess the most straight forward thing would be just to add a 'shift_l' variable > to 'struct scan_type'' and make sure either 'shift_l' or 'shift' is defined and then > properly export either ">>" or "<<" to userspace? Given we already know it's an output channel, can we not just use that to make the decision? Jonathan > > - Nuno Sá >
