Re: [PATCH 2/4] xhci: turn off port power in shutdown

[Mathias Nyman <mathias.nyman@linux.intel.com>]

On 19.7.2022 16.42, Joey Corleone wrote:
> On 23.06.22 13:19, Mathias Nyman wrote:
>> If ports are not turned off in shutdown then runtime suspended
>> self-powered USB devices may survive in U3 link state over S5.
>>
>> During subsequent boot, if firmware sends an IPC command to program
>> the port in DISCONNECT state, it will time out, causing significant
>> delay in the boot time.
>>
>> Turning off roothub port power is also recommended in xhci
>> specification 4.19.4 "Port Power" in the additional note.
>>
>> Cc: stable@vger.kernel.org
>> Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
>> ---
>>   drivers/usb/host/xhci-hub.c |  2 +-
>>   drivers/usb/host/xhci.c     | 15 +++++++++++++--
>>   drivers/usb/host/xhci.h     |  2 ++
>>   3 files changed, 16 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/usb/host/xhci-hub.c b/drivers/usb/host/xhci-hub.c
>> index c54f2bc23d3f..0fdc014c9401 100644
>> --- a/drivers/usb/host/xhci-hub.c
>> +++ b/drivers/usb/host/xhci-hub.c
>> @@ -652,7 +652,7 @@ struct xhci_hub *xhci_get_rhub(struct usb_hcd *hcd)
>>    * It will release and re-aquire the lock while calling ACPI
>>    * method.
>>    */
>> -static void xhci_set_port_power(struct xhci_hcd *xhci, struct usb_hcd *hcd,
>> +void xhci_set_port_power(struct xhci_hcd *xhci, struct usb_hcd *hcd,
>>                   u16 index, bool on, unsigned long *flags)
>>       __must_hold(&xhci->lock)
>>   {
>> diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
>> index cb99bed5f755..65858f607437 100644
>> --- a/drivers/usb/host/xhci.c
>> +++ b/drivers/usb/host/xhci.c
>> @@ -791,6 +791,8 @@ static void xhci_stop(struct usb_hcd *hcd)
>>   void xhci_shutdown(struct usb_hcd *hcd)
>>   {
>>       struct xhci_hcd *xhci = hcd_to_xhci(hcd);
>> +    unsigned long flags;
>> +    int i;
>>       if (xhci->quirks & XHCI_SPURIOUS_REBOOT)
>>           usb_disable_xhci_ports(to_pci_dev(hcd->self.sysdev));
>> @@ -806,12 +808,21 @@ void xhci_shutdown(struct usb_hcd *hcd)
>>           del_timer_sync(&xhci->shared_hcd->rh_timer);
>>       }
>> -    spin_lock_irq(&xhci->lock);
>> +    spin_lock_irqsave(&xhci->lock, flags);
>>       xhci_halt(xhci);
>> +
>> +    /* Power off USB2 ports*/
>> +    for (i = 0; i < xhci->usb2_rhub.num_ports; i++)
>> +        xhci_set_port_power(xhci, xhci->main_hcd, i, false, &flags);
>> +
>> +    /* Power off USB3 ports*/
>> +    for (i = 0; i < xhci->usb3_rhub.num_ports; i++)
>> +        xhci_set_port_power(xhci, xhci->shared_hcd, i, false, &flags);
>> +
>>       /* Workaround for spurious wakeups at shutdown with HSW */
>>       if (xhci->quirks & XHCI_SPURIOUS_WAKEUP)
>>           xhci_reset(xhci, XHCI_RESET_SHORT_USEC);
>> -    spin_unlock_irq(&xhci->lock);
>> +    spin_unlock_irqrestore(&xhci->lock, flags);
>>       xhci_cleanup_msix(xhci);
>> diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
>> index 0bd76c94a4b1..28aaf031f9a8 100644
>> --- a/drivers/usb/host/xhci.h
>> +++ b/drivers/usb/host/xhci.h
>> @@ -2196,6 +2196,8 @@ int xhci_hub_control(struct usb_hcd *hcd, u16 typeReq, u16 wValue, u16 wIndex,
>>   int xhci_hub_status_data(struct usb_hcd *hcd, char *buf);
>>   int xhci_find_raw_port_number(struct usb_hcd *hcd, int port1);
>>   struct xhci_hub *xhci_get_rhub(struct usb_hcd *hcd);
>> +void xhci_set_port_power(struct xhci_hcd *xhci, struct usb_hcd *hcd, u16 index,
>> +             bool on, unsigned long *flags);
>>   void xhci_hc_died(struct xhci_hcd *xhci);
> 
> fyi: there is a report [1] about a regression introduced by this patch.
> 
> Joey
> 
> [1] https://bugzilla.kernel.org/show_bug.cgi?id=216243

Thanks for the notice, I'm away until August.
If it starts to cause more issues then this one incident then it should be reverted.

Will take a look at this when I return.
Meanwhile a log with xhci dynamic debug enabled could better show what is going on

mount -t debugfs none /sys/kernel/debug
echo 'module xhci_hcd =p' >/sys/kernel/debug/dynamic_debug/control

Thanks
Mathias