diff options
| author | Nicolas Boichat <drinkcat@chromium.org> | 2018-05-28 14:32:18 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-05-31 12:48:17 +0200 |
| commit | 25244227158e1502062041365a439a54cb8fe673 (patch) | |
| tree | 87af664545c88bc045cd1598c79caad305d77178 /include/linux/usb.h | |
| parent | 380375b937211376f1dba4543460a14d3df9f04d (diff) | |
| download | lwn-25244227158e1502062041365a439a54cb8fe673.tar.gz lwn-25244227158e1502062041365a439a54cb8fe673.zip | |
usb: hub: Per-port setting to use old enumeration scheme
The "old" enumeration scheme is considerably faster (it takes
~244ms instead of ~356ms to get the descriptor).
It is currently only possible to use the old scheme globally
(/sys/module/usbcore/parameters/old_scheme_first), which is not
desirable as the new scheme was introduced to increase compatibility
with more devices.
However, in our case, we care about time-to-active for a specific
USB device (which we make the firmware for), on a specific port
(that is pogo-pin based: not a standard USB port). This new
sysfs option makes it possible to use the old scheme on a single
port only.
Signed-off-by: Nicolas Boichat <drinkcat@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include/linux/usb.h')
| -rw-r--r-- | include/linux/usb.h | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/include/linux/usb.h b/include/linux/usb.h index beffceec4915..2ade17992ed6 100644 --- a/include/linux/usb.h +++ b/include/linux/usb.h @@ -490,6 +490,13 @@ enum usb_port_connect_type { }; /* + * USB port quirks. + */ + +/* For the given port, prefer the old (faster) enumeration scheme. */ +#define USB_PORT_QUIRK_OLD_SCHEME BIT(0) + +/* * USB 2.0 Link Power Management (LPM) parameters. */ struct usb2_lpm_parameters { |