On Tue, Mar 24, 2015 at 11:52:04AM -0500, Liu, Bin wrote:
> Felipe,
>
> > -----Original Message-----
> > From: Balbi, Felipe
> > Sent: Tuesday, March 24, 2015 11:31 AM
> > To: Liu, Bin
> > Cc: linux-usb@xxxxxxxxxxxxxxx; 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-liu@xxxxxx>
> > > ---
> > > 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;
> }
> }
USB2 spec says you *must* go through a bus reset in order to get out of
testmode. So if you want to change test_j to test_k, you must first bus
reset.
--
balbi
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