| Message ID | 20200109051448.28150-1-nobuta.keiya@fujitsu.com (mailing list archive) |
|---|---|
| State | Mainlined |
| Commit | 9c06ac4c83df6d6fbdbf7488fbad822b4002ba19 |
| Headers | show |
| Series | usb: core: hub: Improved device recognition on remote wakeup | expand |
On Thu, 9 Jan 2020, Keiya Nobuta wrote: > If hub_activate() is called before D+ has stabilized after remote > wakeup, the following situation might occur: > > __ ___________________ > / \ / > D+ __/ \__/ > > Hub _______________________________ > | ^ ^ ^ > | | | | > Host _____v__|___|___________|______ > | | | | > | | | \-- Interrupt Transfer (*3) > | | \-- ClearPortFeature (*2) > | \-- GetPortStatus (*1) > \-- Host detects remote wakeup > > - D+ goes high, Host starts running by remote wakeup > - D+ is not stable, goes low > - Host requests GetPortStatus at (*1) and gets the following hub status: > - Current Connect Status bit is 0 > - Connect Status Change bit is 1 > - D+ stabilizes, goes high > - Host requests ClearPortFeature and thus Connect Status Change bit is > cleared at (*2) > - After waiting 100 ms, Host starts the Interrupt Transfer at (*3) > - Since the Connect Status Change bit is 0, Hub returns NAK. > > In this case, port_event() is not called in hub_event() and Host cannot > recognize device. To solve this issue, flag change_bits even if only > Connect Status Change bit is 1 when got in the first GetPortStatus. > > This issue occurs rarely because it only if D+ changes during a very > short time between GetPortStatus and ClearPortFeature. However, it is > fatal if it occurs in embedded system. > > Signed-off-by: Keiya Nobuta <nobuta.keiya@fujitsu.com> > --- > drivers/usb/core/hub.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c > index f229ad6..77f8eb1 100644 > --- a/drivers/usb/core/hub.c > +++ b/drivers/usb/core/hub.c > @@ -1192,6 +1192,7 @@ static void hub_activate(struct usb_hub *hub, enum hub_activation_type type) > * PORT_OVER_CURRENT is not. So check for any of them. > */ > if (udev || (portstatus & USB_PORT_STAT_CONNECTION) || > + (portchange & USB_PORT_STAT_C_CONNECTION) || > (portstatus & USB_PORT_STAT_OVERCURRENT) || > (portchange & USB_PORT_STAT_C_OVERCURRENT)) > set_bit(port1, hub->change_bits); I would have added the new test one line lower, so that all the portstatus checks were adjacent and all the portchange checks were adjacent. But that's a very small thing... Acked-by: Alan Stern <stern@rowland.harvard.edu>
On Thu, Jan 09, 2020 at 02:14:48PM +0900, Keiya Nobuta wrote: > If hub_activate() is called before D+ has stabilized after remote > wakeup, the following situation might occur: > > __ ___________________ > / \ / > D+ __/ \__/ > > Hub _______________________________ > | ^ ^ ^ > | | | | > Host _____v__|___|___________|______ > | | | | > | | | \-- Interrupt Transfer (*3) > | | \-- ClearPortFeature (*2) > | \-- GetPortStatus (*1) > \-- Host detects remote wakeup > > - D+ goes high, Host starts running by remote wakeup > - D+ is not stable, goes low > - Host requests GetPortStatus at (*1) and gets the following hub status: > - Current Connect Status bit is 0 > - Connect Status Change bit is 1 > - D+ stabilizes, goes high > - Host requests ClearPortFeature and thus Connect Status Change bit is > cleared at (*2) > - After waiting 100 ms, Host starts the Interrupt Transfer at (*3) > - Since the Connect Status Change bit is 0, Hub returns NAK. > > In this case, port_event() is not called in hub_event() and Host cannot > recognize device. To solve this issue, flag change_bits even if only > Connect Status Change bit is 1 when got in the first GetPortStatus. > > This issue occurs rarely because it only if D+ changes during a very > short time between GetPortStatus and ClearPortFeature. However, it is > fatal if it occurs in embedded system. > > Signed-off-by: Keiya Nobuta <nobuta.keiya@fujitsu.com> > --- > drivers/usb/core/hub.c | 1 + > 1 file changed, 1 insertion(+) Is this something that should go into 5.5-final and the stable trees? Or is it ok for 5.6-rc1? thanks, greg k-h
Hi Greg, > Is this something that should go into 5.5-final and the stable trees? > Or is it ok for 5.6-rc1? It is ok for 5.6-rc1 (I'm glad it goes into both). thanks, Keiya Nobuta
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c index f229ad6..77f8eb1 100644 --- a/drivers/usb/core/hub.c +++ b/drivers/usb/core/hub.c @@ -1192,6 +1192,7 @@ static void hub_activate(struct usb_hub *hub, enum hub_activation_type type) * PORT_OVER_CURRENT is not. So check for any of them. */ if (udev || (portstatus & USB_PORT_STAT_CONNECTION) || + (portchange & USB_PORT_STAT_C_CONNECTION) || (portstatus & USB_PORT_STAT_OVERCURRENT) || (portchange & USB_PORT_STAT_C_OVERCURRENT)) set_bit(port1, hub->change_bits);
If hub_activate() is called before D+ has stabilized after remote wakeup, the following situation might occur: __ ___________________ / \ / D+ __/ \__/ Hub _______________________________ | ^ ^ ^ | | | | Host _____v__|___|___________|______ | | | | | | | \-- Interrupt Transfer (*3) | | \-- ClearPortFeature (*2) | \-- GetPortStatus (*1) \-- Host detects remote wakeup - D+ goes high, Host starts running by remote wakeup - D+ is not stable, goes low - Host requests GetPortStatus at (*1) and gets the following hub status: - Current Connect Status bit is 0 - Connect Status Change bit is 1 - D+ stabilizes, goes high - Host requests ClearPortFeature and thus Connect Status Change bit is cleared at (*2) - After waiting 100 ms, Host starts the Interrupt Transfer at (*3) - Since the Connect Status Change bit is 0, Hub returns NAK. In this case, port_event() is not called in hub_event() and Host cannot recognize device. To solve this issue, flag change_bits even if only Connect Status Change bit is 1 when got in the first GetPortStatus. This issue occurs rarely because it only if D+ changes during a very short time between GetPortStatus and ClearPortFeature. However, it is fatal if it occurs in embedded system. Signed-off-by: Keiya Nobuta <nobuta.keiya@fujitsu.com> --- drivers/usb/core/hub.c | 1 + 1 file changed, 1 insertion(+)