diff options
| author | Dan Williams <dan.j.williams@intel.com> | 2014-05-20 18:08:12 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-05-27 16:35:09 -0700 |
| commit | 9262c19d14c433a6a1ba25c3ff897cb89e412309 (patch) | |
| tree | 50f83b859b251a3e842953e4fb9619a05ece02da /drivers/usb/core/hub.h | |
| parent | 600856c231ccb0cbf8afcf09066a8ab2a93ab03d (diff) | |
usb: disable port power control if not supported in wHubCharacteristics
A hub indicates whether it supports per-port power control via the
wHubCharacteristics field in its descriptor. If it is not supported
a hub will still emulate ClearPortPower(PORT_POWER) requests by
stopping the link state machine. However, since this does not save
power do not bother suspending.
This also consolidates support checks into a
hub_is_port_power_switchable() helper.
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/usb/core/hub.h')
| -rw-r--r-- | drivers/usb/core/hub.h | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/drivers/usb/core/hub.h b/drivers/usb/core/hub.h index f9b521e60128..4bd72dd303d5 100644 --- a/drivers/usb/core/hub.h +++ b/drivers/usb/core/hub.h @@ -112,6 +112,16 @@ extern int hub_port_debounce(struct usb_hub *hub, int port1, extern int usb_clear_port_feature(struct usb_device *hdev, int port1, int feature); +static inline bool hub_is_port_power_switchable(struct usb_hub *hub) +{ + __le16 hcs; + + if (!hub) + return false; + hcs = hub->descriptor->wHubCharacteristics; + return (le16_to_cpu(hcs) & HUB_CHAR_LPSM) < HUB_CHAR_NO_LPSM; +} + static inline int hub_port_debounce_be_connected(struct usb_hub *hub, int port1) { |