On Thu, 2020-03-26 at 08:44 +0100, Lars-Peter Clausen wrote: > [External] > > On 3/26/20 8:42 AM, Ardelean, Alexandru wrote: > > On Wed, 2020-03-25 at 17:57 +0200, Andy Shevchenko wrote: > > > [External] > > > > > > On Wed, Mar 25, 2020 at 12:02 PM Alexandru Ardelean > > > <alexandru.ardelean@xxxxxxxxxx> 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. > > > > > > > > Currently, without this patch enabling a buffer is possible and no error > > > > is > > > > produced. With this patch -EINVAL is returned. > > > > > > > > An example of execution with this patch and some instrumented print- > > > > code: > > > > root@analog:~# cd /sys/bus/iio/devices/iio\:device3/buffer > > > > root@analog:/sys/bus/iio/devices/iio:device3/buffer# echo 1 > enable > > > > 0: iio_verify_update 748 indio_dev->masklength 2 *insert_buffer- > > > > > scan_mask 00000000 > > > > 1: iio_verify_update 753 > > > > 2:__iio_update_buffers 1115 ret -22 > > > > 3: iio_buffer_store_enable 1241 ret -22 > > > > -bash: echo: write error: Invalid argument > > > > 1, 2 & 3 are exit-error paths. 0 the first print in iio_verify_update() > > > > rergardless of error path. > > > > > > > > Without this patch (and same instrumented print-code): > > > > root@analog:~# cd /sys/bus/iio/devices/iio\:device3/buffer > > > > root@analog:/sys/bus/iio/devices/iio:device3/buffer# echo 1 > enable > > > > 0: iio_verify_update 748 indio_dev->masklength 2 *insert_buffer- > > > > > scan_mask 00000000 > > > > root@analog:/sys/bus/iio/devices/iio:device3/buffer# > > > > Buffer is enabled with no error. > > > > > > > > Signed-off-by: Lars-Peter Clausen <lars@xxxxxxxxxx> > > > > Signed-off-by: Alexandru Ardelean <alexandru.ardelean@xxxxxxxxxx> > > > > --- > > > > > > > > Changelog v1 -> v2: > > > > * moved check in iio_verify_update() > > > > * added dev_dbg() message; should help some folks understand the message > > > > * documented steps to reproduce > > > > * added Fixes tag; hopefully the tag is the good one; if needed, it can > > > > be > > > > dropped; this has been around for ~8 years; no idea if it's worth > > > > backporting > > > Where? > > stable/fixes/lts-kernels > > don't have a really good clue about where these things need backporting; > What Andy means is that there is no Fixes tag :) oh crap.... i added one but seem to have lost it when moving the patch to the server from where i do git-send i'll add one;
