> -----Original Message----- > From: Felipe Balbi [mailto:balbi@xxxxxx] > Sent: Tuesday, January 27, 2015 7:45 PM > To: Krzysztof Opasiak > Cc: balbi@xxxxxx; linux-usb@xxxxxxxxxxxxxxx; > gregkh@xxxxxxxxxxxxxxxxxxx; bigeasy@xxxxxxxxxxxxx; > s.wadas@xxxxxxxxxxx; k.lewandowsk@xxxxxxxxxxx; > m.szyprowski@xxxxxxxxxxx; andrzej.p@xxxxxxxxxxx > Subject: Re: [PATCH] usb: gadget: composite: Provide list of > registered functions > > Hi, > > On Tue, Jan 27, 2015 at 06:24:42PM +0100, Krzysztof Opasiak wrote: > > > > So I must have misunderstood something. > > > > > > > > I'm not sure if this is a good idea. > > > > Some userspace depends on assumption that sys/kernel/config > > > directory > > > > is empty and it's default place for mounting configfs. > > > > > > and that's fine, they can certainly assume that. Once configfs > is > > > mounted, we will have a new /sys/kernel/config/usb-functions > > > directory. > > > > > > Inside that directory we should have a file which contains your > list > > > of available functions :-) I don't see what the problem is with > that > > > :-s > > > > > > > Please hold done I don't get it. Let's clarify. > > _________________________________________ > / Hello! I'm a programmer cow who can \ > | explain ConfigFS-related questions much | better than Felipe > Balbi. > | What we need | > | in this case is just for the our USB | > | Gadget ConfigFS port to create the file | > | when that is mounted. Just have the | > | file come with /usb_gadget. Not ProcFS, | not SysFS, but with > ConfigFS > | and we're | > | good to go. Let me know if I can | > \ explain anything further / > ----------------------------------------- > \ ^__^ > \ (Oo)\_______ > (__)\ )\/\ > ||----w | > || || > > > Would you like to register a separate usb-functions subsystem in > > configfs only to expose there a list of available functions? As > far as > > I know it's the only way of creating anything in configfs root. > > > > So you would get: > > > > $ ls /sys/kernel/config > > usb-gadget usb-functions > > > > > > Or it is just a typo and you would like to place a usb-functions > > attribute in usb-gadget directory? > > In this option we will get: > > > > $ ls /sys/kernel/config > > usb-gadget > > $ ls /sys/kernel/config/usb-gadget > > usb-function > > $ cat usb-function > > acm > > ecm > > ... > > ______________________________________ > / Hello again. This is exactly what I \ > | have in mind. Thank you. Let's just | call it a more descriptive > name > | like | > \ 'available_functions' / > -------------------------------------- > \ ^__^ > \ (Oo)\_______ > (__)\ )\/\ > ||----w | > || || > I have written this few times in previous emails but our new friend could miss those emails so once again esp. for beautiful cow from a rubber duck: IMPORTANT______________________________________________ / \ | Adding a file to usb_gadget directory is an *ABI break*.| \_________________ _____________________________________ / // // ..---..// .' _ `. __..' (o) : `..__ ; `. / ; `..---...___ .' `~-. .-') . ' _.' : : \ ' + J `._ _.' `~--....___...---~' mh Currently each valid file name is also suitable for gadget. There is no additional restrictions. No matter what name we will give to this new file this name could be used previously by someone in userspace. His program could be broken after kernel upgrade. Moreover some broken userspace programs may relay on fact that usb-gadget directory contains only gadget dirs. And some other things there is a lot of possible breaks in userspace. Best regards, -- Krzysztof Opasiak Samsung R&D Institute Poland Samsung Electronics k.opasiak@xxxxxxxxxxx -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
