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    SubjectRe: [PATCH] usb: dwc3: be more verbose on ERRATIC_ERROR interrupt
    On Wed, Oct 15, 2014 at 10:01:45AM -0700, David Cohen wrote:
    > On Wed, Oct 15, 2014 at 09:57:18AM -0700, David Cohen wrote:
    > > On Wed, Oct 15, 2014 at 12:00:22AM -0500, Felipe Balbi wrote:
    > > > Hi,
    > > >
    > > > On Tue, Oct 14, 2014 at 01:15:05PM -0700, David Cohen wrote:
    > > > > ERRATIC_ERROR interrupt is an event that needs more attention from
    > > > > developers than currently implemented, since this indicates a serious
    > > > > stability issue. The only way to get warned about it is by selecting the
    > > > > maximum driver's verbosity.
    > > > >
    > > > > This patch increases a bit the error's verbosity.
    > > > >
    > > > > Signed-off-by: David Cohen <david.a.cohen@linux.intel.com>
    > > > > ---
    > > > > drivers/usb/dwc3/gadget.c | 3 ++-
    > > > > 1 file changed, 2 insertions(+), 1 deletion(-)
    > > > >
    > > > > diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
    > > > > index 3818b26bfc05..132e761d62e4 100644
    > > > > --- a/drivers/usb/dwc3/gadget.c
    > > > > +++ b/drivers/usb/dwc3/gadget.c
    > > > > @@ -2484,7 +2484,8 @@ static void dwc3_gadget_interrupt(struct dwc3 *dwc,
    > > > > dev_vdbg(dwc->dev, "Start of Periodic Frame\n");
    > > > > break;
    > > > > case DWC3_DEVICE_EVENT_ERRATIC_ERROR:
    > > > > - dev_vdbg(dwc->dev, "Erratic Error\n");
    > > > > + WARN_ON_ONCE(1);
    > > > > + dev_dbg(dwc->dev, "Erratic Error\n");
    > > >
    > > > how about:
    > > > WARN_ONCE(true, "Erratic Error\n");
    > > >
    > > > instead ?
    > >
    > > When erratic error event happens, in my experience it is usually
    > > followed but many of them in a row. It may end up too verbose.
    >
    > Oops, sorry for my confusion. I read WARN(), not WARN_ONCE() when I read
    > for the first time :)
    >
    > I let the dev_dbg() because it may be useful to get all the occurrences
    > in case debug is enabled. But WARN_ONCE() is fine too if you prefer.

    We might WARN_ONCE() and forcibly disconnect from host as the platform
    worn't work anymore after Erratic Error happens. Then just make that
    clear with "Erratic Error: disconnecting from host\n" or something like
    that.

    The only way to fix erratic error (by fixing code - probably PHY driver)
    will require rebooting the platform anyway. At a minimum, you'd have to
    unload and reload dwc3.ko, just make sure (if you can reproduce erratic
    error easily) modprobe -r dwc3 && modprobe dwc3 still causes dwc3 to
    reconnect to host.

    cheers

    --
    balbi
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