On Fri, 20 Mar 2020 11:16:12 +0000 "Ardelean, Alexandru" <alexandru.Ardelean@xxxxxxxxxx> wrote: > On Fri, 2020-03-20 at 11:55 +0100, Lars-Peter Clausen wrote: > > On 3/20/20 11:40 AM, Alexandru Ardelean wrote: > > > From: Lars-Peter Clausen <lars@xxxxxxxxxx> > > > > > > Before activating a buffer make sure that at least one channel is enabled. > > > Activating a buffer with 0 channels enabled doesn't make too much sense and > > > disallowing this case makes sure that individual driver don't have to add > > > special case code to handle it. > > > > > > Signed-off-by: Lars-Peter Clausen <lars@xxxxxxxxxx> > > > Signed-off-by: Alexandru Ardelean <alexandru.ardelean@xxxxxxxxxx> > > > --- > > > > > > * Found this relic-patch in our tree, from 6 years ago: > > > https://github.com/analogdevicesinc/linux/commit/6d680e49d459c > > > It got moved around a bit, and this is the current form in the ADI tree. > > > So, this is also a bit of an RFC, but if the idea is valid, maybe it's > > > worth considering upstream. I don't know of any arguments against it, > > > but I could be surprised. > > > > Hm, a bit weird that this one never made it upstream considering how > > simple it is. > > > > Did you check that the issue still occurs? I can't see anything in the > > code that prevents it, but who knows, maybe it was fixed by something else. > > i did not think to check behavior/issues; > i'll try to make some time for that; I can't immediately think of anything that would stop this case. However, good if you could confirm it. (I don't have a setup running right now to test against) > i caught this one while diff-ing the upstream & ADI trees, and i needed to dig a > bit more into the ADI git history on it; > > i was a bit puzzled for a while, because some rework patches were upstreamed > without this patch: > > https://lore.kernel.org/linux-iio/55585CAA.6000506@xxxxxxxxxx/ > https://lore.kernel.org/linux-iio/5560685A.5060504@xxxxxxxxxx/ > > i also did not find any discussions/upstream attempt for this patch particularly > > so, it was easier for me just to RFC this > > > > > > drivers/iio/industrialio-buffer.c | 6 ++++++ > > > 1 file changed, 6 insertions(+) > > > > > > diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio- > > > buffer.c > > > index 4ada5592aa2b..f222a118d0d3 100644 > > > --- a/drivers/iio/industrialio-buffer.c > > > +++ b/drivers/iio/industrialio-buffer.c > > > @@ -1031,6 +1031,12 @@ static int __iio_update_buffers(struct iio_dev > > > *indio_dev, > > > return ret; > > > > > > if (insert_buffer) { > > > + if (bitmap_empty(insert_buffer->scan_mask, > > > + indio_dev->masklength)) { > > > + ret = -EINVAL; > > > + goto err_free_config; > > > + } > > > > Since the check is so simple it might make sense to do it as the very > > first thing before iio_verify_update(). > > works for me; > > > > > > + > > > ret = iio_buffer_request_update(indio_dev, insert_buffer); > > > if (ret) > > > goto err_free_config; > > >
