On Sun, Nov 06, 2022 at 09:47:05PM +0900, Vincent MAILHOL wrote: > On Sun. 6 Nov. 2022 at 20:25, Greg Kroah-Hartman > <gregkh@xxxxxxxxxxxxxxxxxxx> wrote: > > 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? > > OK for me. Will do that and remove the kernel log spam and replace it > by a sysfs entry. > > I have two questions: > > 1/ Can I still export and use usb_cache_string()? In other terms, does > the first patch of this series still apply? This looks like the most > convenient function to retrieve that custom string to me. Everyone seems to just use the usb_string() function, will that not work for you? > 2/ Is it a no-go to also populate ethtool_drvinfo::fw_version? Some > users might look for the value in sysfs, while some might use ethtool. > If the info is not available in ethtool, people might simply assume it > is not available at all. So, I would like to provide both. That's up to the network developers/maintainers. I don't know if that's a required or common api for network devices to have. thanks, greg k-h
