RE: [PATCH v2] usb: gadget: f_mass_storage: Make CD-ROM emulation works with Windows OS

From: Neal Liu
Date: Sun Jun 26 2022 - 22:31:14 EST


> On Fri, Jun 24, 2022 at 10:19:16AM +0800, Neal Liu wrote:
> > Add read TOC with format 1 to support CD-ROM emulation with
>
> What is "TOC"? What is "format 1"?
>
> > Windows OS.
>
> Which versions of Windows support this?
>
> > This patch is tested on Windows OS Server 2019.
>
> Does this fix a regression where we used to support this? Or is this a new
> feature of Windows?

We used to support this. I should add "Fixes" for the information.

>
>
> >
> > Signed-off-by: Neal Liu <neal_liu@xxxxxxxxxxxxxx>
> > ---
> > drivers/usb/gadget/function/f_mass_storage.c | 5 +++--
> > 1 file changed, 3 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/usb/gadget/function/f_mass_storage.c
> > b/drivers/usb/gadget/function/f_mass_storage.c
> > index 3a77bca0ebe1..9edf76c22605 100644
> > --- a/drivers/usb/gadget/function/f_mass_storage.c
> > +++ b/drivers/usb/gadget/function/f_mass_storage.c
> > @@ -1209,7 +1209,8 @@ static int do_read_toc(struct fsg_common
> > *common, struct fsg_buffhd *bh)
> >
> > switch (format) {
> > case 0:
> > - /* Formatted TOC */
> > + case 1:
> > + /* Formatted TOC, Session info */
> > len = 4 + 2*8; /* 4 byte header + 2 descriptors */
> > memset(buf, 0, len);
> > buf[1] = len - 2; /* TOC Length excludes length field */
> > @@ -1250,7 +1251,7 @@ static int do_read_toc(struct fsg_common
> *common, struct fsg_buffhd *bh)
> > return len;
> >
> > default:
> > - /* Multi-session, PMA, ATIP, CD-TEXT not supported/required */
> > + /* PMA, ATIP, CD-TEXT not supported/required */
>
> So case 1 is "multi-session"? Please document this properly.
>

Okay, I'll revise it properly.