Re: [PATCH] usb: misc: cypress_cy7c63: check control transfer status

[Greg KH]

On Fri, Jul 10, 2026 at 11:53:31AM +0200, Oliver Neukum wrote:
> On 10.07.26 01:30, Keshav Verma wrote:
> > read_port() currently ignores errors from vendor_command() and always
> > returns the cached port value. This can report stale data when the USB
> > control transfer fails or returns a short response.
> > 
> > Convert vendor_command() to usb_control_msg_recv(), which returns 0 on
> > success and a negative errno on failure, and propagate transport errors
> > from read_port() instead of returning cached data.
> 
> Hi,
> 
> Thank you for making a patch for this issue.
> I am sorry, but this approach mixes issues that are real with something
> that is not a problem.
> > Fixes: 9189bfc2df0f ("[PATCH] USB: rename Cypress CY7C63xxx driver to
> > proper name and fix up some tiny things")
> > Signed-off-by: Keshav Verma <iganschel@xxxxxxxxx>
> > ---
> > v2:
> 
> > -       retval = usb_control_msg(dev->udev, pipe, request,
> > -                                USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_OTHER,
> > -                                address, data, iobuf, CYPRESS_MAX_REQSIZE,
> > -                                USB_CTRL_GET_TIMEOUT);
> 
> This does return errors.

Yes, but they are not checked properly, as your patch showed.

> > -       /* we must not process garbage */
> > -       if (retval < 2)
> > +       dev_dbg(&dev->udev->dev, "Sending usb_control_msg_recv (data:
> > %d)\n", data);
> > +
> > +       retval = usb_control_msg_recv(dev->udev, 0, request,
> 
> There is no point in this change. You just allocate yet another
> buffer for no gain.

That's not an issue, we should be moving all drivers away from
usb_control_msg() as it's used wrong so many times (like this one.)

So I think this is the correct thing to be doing here.

thanks,

greg k-h