On 28.6.2021 9.55, Jung Daehwan wrote:
> 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:
>>> On Tue, Jun 22, 2021 at 09:56:20PM +0200, Greg Kroah-Hartman wrote:
>>>> On Tue, Jun 22, 2021 at 08:24:56PM +0900, Daehwan Jung wrote:
>>>>> 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.
>>>
>>>> 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);
>
We can check the xhci_reset() return value here and print a message, makes sense.
The original reason for the 10 second timeout was because a host actually took 9 seconds:
commit 22ceac191211cf6688b1bf6ecd93c8b6bf80ed9b
xhci: Increase reset timeout for Renesas 720201 host.
The NEC/Renesas 720201 xHCI host controller does not complete its reset
within 250 milliseconds. In fact, it takes about 9 seconds to reset the
host controller, and 1 second for the host to be ready for doorbell
rings. Extend the reset and CNR polling timeout to 10 seconds each.
-Mathias
