On 29-07-22, 17:03, Greg Kroah-Hartman wrote:
> On Fri, Jul 29, 2022 at 09:57:52AM -0500, Pierre-Louis Bossart wrote:
> >
> >
> > On 7/29/22 09:52, Greg Kroah-Hartman wrote:
> > > On Fri, Jul 29, 2022 at 09:46:26AM -0500, Pierre-Louis Bossart wrote:
> > >>
> > >>
> > >> On 7/29/22 08:50, Greg Kroah-Hartman wrote:
> > >>> There's no need to special-case the dp0 sysfs attributes, the
> > >>> is_visible() callback in the attribute group can handle that for us, so
> > >>> add that and add it to the attribute group list making the logic simpler
> > >>> overall.
> > >>>
> > >>> This is a step on the way to moving all of the sysfs attribute handling
> > >>> into the default driver core attribute group logic so that the soundwire
> > >>> core does not have to do any of it manually.
> > >>>
> > >>> Cc: Vinod Koul <vkoul@xxxxxxxxxx>
> > >>> Cc: Bard Liao <yung-chuan.liao@xxxxxxxxxxxxxxx>
> > >>> Cc: Pierre-Louis Bossart <pierre-louis.bossart@xxxxxxxxxxxxxxx>
> > >>> Cc: Sanyog Kale <sanyog.r.kale@xxxxxxxxx>
> > >>> Cc: alsa-devel@xxxxxxxxxxxxxxxx
> > >>> Cc: linux-kernel@xxxxxxxxxxxxxxx
> > >>> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> > >>> ---
> > >>> drivers/soundwire/sysfs_slave.c | 18 ++++++++++++------
> > >>> 1 file changed, 12 insertions(+), 6 deletions(-)
> > >>>
> > >>> diff --git a/drivers/soundwire/sysfs_slave.c b/drivers/soundwire/sysfs_slave.c
> > >>> index 83e3f6cc3250..3723333a5c2b 100644
> > >>> --- a/drivers/soundwire/sysfs_slave.c
> > >>> +++ b/drivers/soundwire/sysfs_slave.c
> > >>> @@ -174,6 +174,16 @@ static ssize_t words_show(struct device *dev,
> > >>> }
> > >>> static DEVICE_ATTR_RO(words);
> > >>>
> > >>> +static umode_t dp0_is_visible(struct kobject *kobj, struct attribute *attr,
> > >>> + int n)
> > >>> +{
> > >>> + struct sdw_slave *slave = dev_to_sdw_dev(kobj_to_dev(kobj));
> > >>> +
> > >>> + if (slave->prop.dp0_prop)
> > >>> + return attr->mode;
> > >>> + return 0;
> > >>> +}
> > >>
> > >> This changes the results slightly by creating an empty 'dp0' directory
> > >> with no attributes inside.
> > >>
> > >> Before:
> > >>
> > >> [root@fedora ~]# cd /sys/bus/soundwire/devices/sdw:3:025d:0714:01
> > >> [root@fedora sdw:3:025d:0714:01]# ls dp0
> > >> ls: cannot access 'dp0': No such file or directory
> > >>
> > >> After:
> > >> [root@fedora sdw:3:025d:0714:01]# ls dp0
> > >
> > > That should be fine, tools should just be looking for the attributes,
> > > not the existance of a directory, right?
> >
> > The idea what that we would only expose ports that actually exist.
> > That's helpful information anyone with a basic knowledge of the
> > SoundWire specification would understand.
>
> Is "dp0" a port? If so, why isn't it a real device?
No they are not. It is a logical channel to send data to the device. The
device can have one or many data ports...
So the device logic or usb-endpoint style maynot look good here...
The change looks good though, dp0 maybe present and empty, we should
looks for attributes...
> > The attributes are really details that few people/applications would
> > understand, and unfortunately the information reported in DSDT is more
> > often than not complete garbage.
>
> I don't understand what DSDT is, or how it is relevant here :(
>
> thanks,
>
> greg k-h
--
~Vinod
