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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> Cc: stable <stable@vger.kernel.org> Acked-by: Alan Stern <stern@rowland.harvard.edu> Link: https://lore.kernel.org/r/20200109051448.28150-1-nobuta.keiya@fujitsu.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
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.. | ||
buffer.c | ||
config.c | ||
devices.c | ||
devio.c | ||
driver.c | ||
endpoint.c | ||
file.c | ||
generic.c | ||
hcd-pci.c | ||
hcd.c | ||
hub.c | ||
hub.h | ||
Kconfig | ||
ledtrig-usbport.c | ||
Makefile | ||
message.c | ||
notify.c | ||
of.c | ||
otg_whitelist.h | ||
phy.c | ||
phy.h | ||
port.c | ||
quirks.c | ||
sysfs.c | ||
urb.c | ||
usb-acpi.c | ||
usb.c | ||
usb.h |