On 1/17/20 1:25 AM, Felipe Balbi wrote: > why? No behavior changed. Look at the very first commit on > f_hid.c. commit 71adf118946957839a13aa4d1094183e05c6c094 contains the > following: Oops. I missed that. Sorry for not being complete enough. My fault. > Now, if there's a real usecase for this. Something that can attract, as > per Dave B., 3 or more users, then we can consider adding it > upstream. Remember that if we add support for changing interface > strings, it has to be implemented for *all* functions and validated on > all functions, then properly documented as a configfs ABI which can > never change anymore. Erg. I did not realize that this was not going to be limited to just f_hid.c. That's ... ugly. Reeeally ugly. And a *LOT* of work. I can certainly see that "some devices do this" is nowhere close to enough justification for that. >> control board the ability to now also be accessed via ethernet or >> wireless (or even a better USB protocol) and thus now has an upgrade or >> higher performance path is a *really* useful thing. And the Beaglebone >> Black is a really good "protocol engine". Finally, after making the usb >> gadget emulation work, I can probably blow a bunch of Windows machines >> away completely since something like a Beaglebone Black is more than >> sufficient to handle the control without any outside intervention. > > You're getting to a point where things start to get interesting. What > exactly are you trying to do? I've got both a GPIB (with USB 1.0(!) only--as far as I can tell--talk about a relic) and an industrial controller (unknown protocol but USB tracing and a signal analyzer shows pretty much 1-1 so reverse engineering it doesn't seem problematic) currently sitting on my desk. I have one system which has enough USB devices in it that it won't work on a USB 3 system because the Intel USB 3 chipset allocates twice as many endpoints per device and hits an internal limit--they want a USB upgrade as an intermediate move to ethernet. I have a half-dozen other similar type requests queued behind these. People are finally reaching a critical point where they can't keep ancient hardware, ancient drivers, ancient Windows, and ancient computers all running anymore--even VM's are starting to fail as too many things have some level of timing baked into the driver (normally unintentionally). >> Anyhow, let me know whether I should attack the problem or not. At this point, I suspect that the correct answer is "Keep an eye on this while moving forward." If I stumble over more drivers that are trying to use iInterface for some reason, I will see if setting it to 0x00 makes things choose a different path. Simply changing the default to effectively 0x00-unused seems like a lot less work and might pick up 90% of the use cases. It also means the scope would be limited to f_hid.c. If I hit this a couple times, I'll have a lot more justification behind me. If I start seeing cases where I actually need to specify the iInterface stuff, I'll come back with data and we can revisit this again. I suspect that someone is eventually going to drop a CDC class device in front of me, and that will give me more data, too. If ever I reach the point where I have multiple devices working around this, hopefully you will find my arguments far more persuasive. :) > you could use dummy_hcd as well. Interesting. I did not know about this, but I will keep it in mind. Thanks for being so patient. Sorry for wasting your time only to come back to "do nothing". -a
