Re: [PATCH v3 1/1] usb: gadget: f_fs: Support zerocopy transfers via mmap.

[Greg KH <gregkh@linuxfoundation.org>]

On Fri, Feb 11, 2022 at 08:47:01PM +0100, Ingo.Rohloff@lauterbach.com wrote:
> Hello Greg,
> 
> On Friday, 11 February, 2022 12:02 CET, Greg KH <gregkh@linuxfoundation.org> wrote:
> 
> > On Wed, Feb 09, 2022 at 06:25:07PM +0100, Ingo Rohloff wrote:
> > > This patch implements the same functionality for FunctionFS as
> > > commit f7d34b445abc00e979b7 ("USB: Add support for usbfs zerocopy.")
> > > did for USB host devio.c
> > > ...
> >
> > No documentation of the new mount option here?
> > It should go somewhere, right?
> 
> You are of course right :-).
> But: Do you have any suggestions where to put it?

Where are other filesystem mount options listed?

> I just searched the "Documentation/" directory, but so far I haven't found
> any  description about the mount options available for FunctionFS
> (including the not so obvious "no_disconnect" option).

What about in Documentation/usb/functionfs.rst?

> Of course I can put some minimal description of the mount option
> in the commit message itself; but I think that's not really useful?

It is better than nothing :)

> So maybe it makes more sense to in general write more about FunctionFS.
> The whole mmap mechanism also might need a description somewhere.
> I have some test code here:
>   https://github.com/trace32/test_usb_ffs
> I can also provide that as a patch (with sign-off) , for example under 
>   tools/usb/ffs-aio-example
> (there already is some test code there).

Yes, test code would be great, can you add it to the self-test
framework?

> Would this make sense to you?  I guess that would make more sense as an
> extra patch; at least as an extra commit?

Yes, a patch series would be good.

thanks,

greg k-h