On Sat, Nov 05, 2022 at 08:45:10PM -0400, Alan Stern wrote: > On Sat, Nov 05, 2022 at 06:38:35PM +0100, Greg Kroah-Hartman wrote: > > On Sun, Nov 06, 2022 at 02:21:11AM +0900, Vincent MAILHOL wrote: > > > On Sat. 5 Nov. 2022 at 18:27, Vincent MAILHOL > > > <mailhol.vincent@xxxxxxxxxx> wrote: > > > > On Sat. 5 Nov. 2022 at 17:36, Greg Kroah-Hartman > > > > <gregkh@xxxxxxxxxxxxxxxxxxx> wrote: > > It's late right now, and I can't remember the whole USB spec, but I > > think the device provides a list of the string ids that are valid for > > it. If so, we can add that to sysfs for any USB device out there, no > > matter the string descriptor number. > > No, there is no such list. Yeah, my fault, nevermind about that, sorry. > > If not, maybe we can just iterate the 255 values and populate sysfs > > files if they are present? I'll dig up the USB spec tomorrow... > > Yes, we could do that. But the filename would have to be the string > id, which is not meaningful. We wouldn't be able to have labels like > "product-info" unless somehow a driver could provide the label. We could have a directory of strings/ with the individual descriptors in there as files with the name being the string id. But that might take a long time to populate, as it can take a few tries to get the string from a device, and to do that 256 times might be noticable at device insertion time. > Also, there's the matter of language. Devices can have string > descriptors in multiple languages; which one should we show in sysfs? > All of them? Right now we use just the default language for the strings > that we put in sysfs. > > > I say do this at the USB core level, that way it works for any USB > > device, and you don't have a device-specific sysfs file and custom > > userspace code just for this. > > This is unavoidable to some extent. Without device-specific information > or userspace code, there is no way to know which string descriptor > contains the data you want. Agreed. Ok, for this specific instance, adding the "we know this string id should be here" as a device-specific sysfs file seems to be the easiest way forward. Vincent, want to try that instead? thanks, greg k-h
