Re: usb: host: Reduce xhci_handshake timeout in xhci_reset

On Mon, Jun 28, 2021 at 08:53:02AM +0200, Greg Kroah-Hartman wrote:

On Mon, Jun 28, 2021 at 11:25:48AM +0900, Jung Daehwan wrote:

quoted

On Tue, Jun 22, 2021 at 09:56:20PM +0200, Greg Kroah-Hartman wrote:

quoted

On Tue, Jun 22, 2021 at 08:24:56PM +0900, Daehwan Jung wrote:

quoted

It seems 10 secs timeout is too long in general case. A core would wait for
10 secs without doing other task and it can be happended on every device.

Only if the handshake does not come back sooner, right?

Yes, right.

quoted

What is causing your device to timeout here?

Host Controller doesn't respond handshake. I don't know why and I ask HW team
to debug it.

Please work to fix your hardware, that feels like the root of the
problem here.  If you require the timeout for xhci_reset() to happen,
then how do you know that the hardware really did reset properly in the
reduced amount of time you just provided?

I continue fixing this issue with hardware engineer, but currently just
host controller can crash whole system and that's why I want to fix it.
How about adding some error logs in this situation for recognizing this issue?
We can add error log in xhci_stop as xhci_reset can returns error like below.

static void xhci_stop(struct usb_hcd *hcd)
{
        u32 temp;
        struct xhci_hcd *xhci = hcd_to_xhci(hcd);
+       int ret;

        mutex_lock(&xhci->mutex);

@@ -733,6 +734,9 @@ static void xhci_stop(struct usb_hcd *hcd)
        xhci->cmd_ring_state = CMD_RING_STATE_STOPPED;
        xhci_halt(xhci);
        xhci_reset(xhci);
+       if (ret)
+               xhci_err(xhci, "%s: Error while reset xhci Host controller - ret = %d\n"
+                       , __func__, ret);
        spin_unlock_irq(&xhci->lock);

thanks,

greg k-h