mirros/rockchip-kernel
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

usb: disable port power control if not supported in wHubCharacteristics

Browse Source 
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>
This commit is contained in:
Dan Williams
2014-05-20 18:08:12 -07:00
committed by Greg Kroah-Hartman
parent 600856c231
commit 9262c19d14
3 changed files with 20 additions and 11 deletions
Download Patch File Download Diff File Expand all files Collapse all files

10
drivers/usb/core/hub.h
View File

@@ -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)
{