Re: [PATCH net-next 05/10] lan78xx: Disable USB3 link power state transitions

[Jakub Kicinski <kuba@kernel.org>]

On Tue, 24 Aug 2021 15:33:13 +0100 John Efstathiades wrote:
> > Do you expect the device-initiated transitions to always be causing
> > trouble or are there scenarios where they are useful?  
> 
> It's a particular problem on Android devices.
> 
> > Having to recompile the driver is a middle ground rarely chosen
> > upstream. If the code has very low chance of being useful - let's
> > remove it (git will hold it forever if needed); if there are reasonable
> > chances someone will find it useful it should be configurable from user
> > space, or preferably automatically enabled based on some device match
> > list.  
> 
> I like the sound of the device match list but I don't know what you mean.
> Is there a driver or other reference you could point me at that provides
> additional info?

Depends on what the discriminator is. If problems happen with 
a particular ASIC revisions driver needs to read the revision
out and make a match. If it's product by product you can use
struct usb_device_id :: driver_info to attach metadata per 
device ID. If it's related to the platform things like DMI
matching are sometimes used. I have very limited experience 
with Android / embedded ARM so not sure what would work there.