[PATCH 2/6] ASoC: SOF: Introduce descriptors for SOF client

[gregkh at linuxfoundation.org]

On Mon, Oct 05, 2020 at 10:18:21AM -0500, Pierre-Louis Bossart wrote:
> 
> > > > > > > > As you are creating new sysfs directories, you should have
> > > > > > > > some
> > > > > > > > documentation for them :(
> > > > > > > Hi Greg,
> > > > > > > 
> > > > > > > We are not adding any sysfs entries in this series.
> > > > > > 
> > > > > > You added directories in sysfs, right?
> > > > > Hi Greg,
> > > > > 
> > > > > We are not adding any sysfs directories.
> > > > 
> > > > Really?  Then what does creating these new devices do in sysfs?  If
> > > > nothing, then why are they being used at all?  :)
> > > > 
> > > > > The only change in the /sys directory will be the new ancillary
> > > > > devices created in the /sys/bus/ancillary/devices directory ie
> > > > > snd_sof_client.ipc_test.0 and snd_sof_client.ipc_test.1.
> > > > 
> > > > That is what I was referring to.
> > > > 
> > > > > In the following patches, we're adding debugfs entries for the ipc
> > > > > test clients but no other sysfs changes.
> > > > > 
> > > > > Is it required to add documentation for these as well?
> > > > 
> > > > Why would you not document them?  If you don't do anything with these
> > > > devices, then why even use them?  debugfs does not require sysfs
> > > > entries, so I fail to see the need for using this api at all here...
> > > Hi Greg,
> > > 
> > > Pardon my ignorance here a bit. Typically, when registering platform
> > > devices, we've not added any documentation to highlight how they are
> > > used. Of course thats no excuse for not doing this right.
> > > 
> > > But just to clarify so that we can fix this properly in the next
> > > version, are we expected to add documentation for the directories added
> > > in the /sys/bus (ie /sys/bus/ancillary, /sys/bus/ancillary/devices,
> > > /sys/bus/ancillary/drivers etc) and also for the devices and drivers
> > > added by the SOF driver?
> > 
> > You are using a brand-new interface, which is designed to represent
> > things in the driver model and sysfs properly, and yet your usage
> > doesn't actually take advantage of the driver model or sysfs at all?
> > 
> > That implies to me that you are using this incorrectly.
> 
> We are taking advantage of 'standard' sysfs capabilities, e.g. we get a
> power/ directory and can disable pm_runtime if we chose to do so.
> 
> But the point is that for now we haven't added domain specific properties
> with attributes.
> 
> For example, I noodled with this code last week to replace the platform
> devices with ancillary devices in the Intel SoundWire code, and I get this
> in sysfs:
> 
> root at plb:/sys/bus/ancillary/devices/soundwire_intel.link.0# ls -l
> total 0
> lrwxrwxrwx 1 root root    0 Oct  2 15:48 driver ->
> ../../../../bus/ancillary/drivers/intel-sdw
> lrwxrwxrwx 1 root root    0 Oct  5 10:12 firmware_node ->
> ../../../LNXSYSTM:00/LNXSYBUS:00/PNP0A08:00/device:63/PRP00001:00
> drwxr-xr-x 2 root root    0 Oct  5 10:12 power
> drwxr-xr-x 5 root root    0 Oct  2 15:48 sdw-master-0
> lrwxrwxrwx 1 root root    0 Oct  2 15:48 subsystem ->
> ../../../../bus/ancillary
> -rw-r--r-- 1 root root 4096 Oct  2 15:48 uevent
> 
> What would you want us to document here?

What you think should be in the documentation to help people out with
these devices...

Anyway, this thread is long-dead due to it being only on alsa-devel, I'm
not going to respond anymore here, thanks.

greg k-h