RE: [EXT] Re: [PATCH 1/1] usb: gadget: call usb_gadget_check_config() to verify UDC capability

[Frank Li]

> -----Original Message-----
> From: Roger Quadros <rogerq@xxxxxxxxxx>
> Sent: Wednesday, June 28, 2023 10:23 PM
> To: Frank Li <frank.li@xxxxxxx>; r-gunasekaran@xxxxxx; imx@xxxxxxxxxxxxxxx;
> Jun Li <jun.li@xxxxxxx>; Greg Kroah-Hartman
> <gregkh@xxxxxxxxxxxxxxxxxxx>; Elson Roy Serrao
> <quic_eserrao@xxxxxxxxxxx>; Thinh Nguyen
> <Thinh.Nguyen@xxxxxxxxxxxx>; Andy Shevchenko
> <andriy.shevchenko@xxxxxxxxxxxxxxx>; Jó Ágila Bitsch <jgilab@xxxxxxxxx>;
> Prashanth K <quic_prashk@xxxxxxxxxxx>; Peter Chen
> <peter.chen@xxxxxxxxxx>; open list:USB SUBSYSTEM <linux-
> usb@xxxxxxxxxxxxxxx>; open list <linux-kernel@xxxxxxxxxxxxxxx>
> Subject: [EXT] Re: [PATCH 1/1] usb: gadget: call usb_gadget_check_config()
> to verify UDC capability
> 
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> 
> On 29/06/2023 03:54, Frank Li wrote:
> > The legacy gadget driver omitted calling usb_gadget_check_config()
> > to ensure that the USB device controller (UDC) has adequate resources,
> > including sufficient endpoint numbers and types, to support the given
> > configuration.
> >
> > Previously, usb_add_config() was solely invoked by the legacy gadget
> > driver. Adds the necessary usb_gadget_check_config() after the bind()
> > operation to fix the issue.
> 
> You have only fixed composite.c. Not all gadget drivers use composite.c
> so it will be still broken for them.
> 
> Please also add default sane configuration in CDNS3 so it works even
> if usb_gadget_check_config() is not invoked.

Which one was not call usb_add_config()?
DWC3 also use
 .check_config		= dwc3_gadget_check_config, 
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/usb/dwc3/gadget.c 

I think it is not correct by assume UDC can support specific config
at gadget function driver. 
Add default value of CDNS3 actually hidden potential problem. 

I don't suggest it before fixed hidden potential problem. 

Frank  

> 
> >
> > Fixes: dce49449e04f ("usb: cdns3: allocate TX FIFO size according to
> composite EP number")
> > Reported-by: Ravi Gunasekaran <r-gunasekaran@xxxxxx>
> > Signed-off-by: Frank Li <Frank.Li@xxxxxxx>
> > ---
> >  drivers/usb/gadget/composite.c | 4 ++++
> >  1 file changed, 4 insertions(+)
> >
> > diff --git a/drivers/usb/gadget/composite.c
> b/drivers/usb/gadget/composite.c
> > index 1b3489149e5e..dd9b90481b4c 100644
> > --- a/drivers/usb/gadget/composite.c
> > +++ b/drivers/usb/gadget/composite.c
> > @@ -1125,6 +1125,10 @@ int usb_add_config(struct usb_composite_dev
> *cdev,
> >               goto done;
> >
> >       status = bind(config);
> > +
> > +     if (status == 0)
> > +             status = usb_gadget_check_config(cdev->gadget);
> > +
> >       if (status < 0) {
> >               while (!list_empty(&config->functions)) {
> >                       struct usb_function             *f;
> 
> --
> cheers,
> -roger