On Wed, Nov 18, 2020 at 05:04:36PM +0800, liulongfang wrote:
> On 2020/11/18 15:02, Greg KH Wrote:
> > On Wed, Nov 18, 2020 at 11:36:13AM +0800, Longfang Liu wrote:
> >> The HCE(Host Controller Error) event has been defined in
> >> the XHCI driver but has not been used. If we want to use
> >> the HCE event to reset the controller, can we implement
> >> it in the interrupt function as follows:
> >>
> >> xhci_irq()
> >> |----xhci_halt()
> >> |----xhci_shutdown()
> >> |----xhci_start()
> >> |----xhci_run()
> >>
> >> Signed-off-by: Longfang Liu <liulongfang@xxxxxxxxxx>
> >> ---
> >> drivers/usb/host/xhci-ring.c | 10 ++++++++++
> >> 1 file changed, 10 insertions(+)
> >
> > $ ./scripts/get_maintainer.pl --file drivers/usb/host/xhci-ring.c
> > Mathias Nyman <mathias.nyman@xxxxxxxxx> (supporter:USB XHCI DRIVER)
> > Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> (supporter:USB SUBSYSTEM)
> > linux-usb@xxxxxxxxxxxxxxx (open list:USB XHCI DRIVER)
> > linux-kernel@xxxxxxxxxxxxxxx (open list)
> >
> > Any reason to not include the maintainer of the xhci driver here?
> OK, I will include the maintainer in the next patch.
> >
> >> diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
> >> index 2c255d0..87b3a40 100644
> >> --- a/drivers/usb/host/xhci-ring.c
> >> +++ b/drivers/usb/host/xhci-ring.c
> >> @@ -2857,6 +2857,16 @@ irqreturn_t xhci_irq(struct usb_hcd *hcd)
> >> goto out;
> >> }
> >>
> >> + if (status & STS_HCE) {
> >> + xhci_warn(xhci, "WARNING: Host Controller Error\n");
> >> + xhci_halt(xhci);
> >> + xhci_shutdown(hcd);
> >> + xhci_start(xhci);
> >> + xhci_run(hcd);
> >> + ret = IRQ_HANDLED;
> >> + goto out;
> >> + }
> >> +
> >
> > Does this fix a real problem for you? Are you sure we will not suddenly
> > start resetting devices that were working properly and sending this
> > error incorrectly? How did you test this?
> >
> > thanks,
> >
> > greg k-h
> > .
> >
> Yes, we want to add a RAS feature to the USB,
What is "RAS"?
> Use the HCE event to trigger the reset operation of the USB controller.
Is that allowed by the XHCI specification?
> By searching for the current xhci driver, the driver did not handle HCE event.
> In fact, I am not sure if other operations will cause HCE, The HCE event is
> used to reset the USB controller according to the definition of the event.
What generates that event? Do existing controllers do that today? What
causes it?
> I test this reset operation through the Sysfs file, but have not tested all usage scenarios.
What sysfs file?
thanks,
greg k-h
