Felipe,

> -----Original Message-----
> From: Balbi, Felipe
> Sent: Tuesday, March 24, 2015 11:31 AM
> To: Liu, Bin
> Cc: linux-usb@vger.kernel.org; Balbi, Felipe
> Subject: Re: [PATCH] usb: musb: only set test mode once
> 
> On Fri, Mar 20, 2015 at 04:49:58PM -0500, Bin Liu wrote:
> > The MUSB test mode register can only be set once, otherwise the result
> > is undefined.
> >
> > This prevents the debugfs testmode entry to set the register more than
> > once which causes test failure.
> >
> > Signed-off-by: Bin Liu <b-...@ti.com>
> > ---
> >  drivers/usb/musb/musb_debugfs.c | 6 ++++++
> >  1 file changed, 6 insertions(+)
> >
> > diff --git a/drivers/usb/musb/musb_debugfs.c
> > b/drivers/usb/musb/musb_debugfs.c index 78a283e..cd0c381 100644
> > --- a/drivers/usb/musb/musb_debugfs.c
> > +++ b/drivers/usb/musb/musb_debugfs.c
> > @@ -194,6 +194,12 @@ static ssize_t musb_test_mode_write(struct file *file,
> >     u8                      test = 0;
> >     char                    buf[18];
> >
> > +   test = musb_readb(musb->mregs, MUSB_TESTMODE);
> > +   if (test) {
> > +           dev_err(musb->controller, "Error: test mode is running\n");
> 
> with this message, user doesn't really know exactly what to do. Perhaps 
> mention
> that a USB Bus Reset is needed to get the thing out of test mode?

Ok, will change it. How about only print the error message when the new test 
mode is different from the running one, and silently do nothing if the new test 
mode is the same. Something like

if (test) {
    if (new test is different) {
        dev_err(...);
        return -EINVAL;
    } else {
        return 0;
    }
}

Regards,
-Bin.

> 
> --
> balbi
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