diff options
| author | Mathias Nyman <mathias.nyman@linux.intel.com> | 2022-05-06 19:18:07 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-06-12 06:49:47 +0200 |
| commit | e146caf303493c4f2458173d7f1598b76a9b1396 (patch) | |
| tree | c919d4800c067113da371c60ba8b767ec0a965a1 /include/linux/usb.h | |
| parent | 3085d1bd47f2bfdd0b34b8399011f2ed6292fe8c (diff) | |
usb: Avoid extra usb SET_SEL requests when enabling link power management
The host needs to tell the device the exit latencies using the SET_SEL
request before device initiated link powermanagement can be enabled.
The exit latency values do not change after enumeration, it's enough
to set them once. So do like Windows 10 and issue the SET_SEL request
once just before setting the configuration.
This is also the sequence described in USB 3.2 specs "9.1.2 Bus
enumeration". SET_SEL is issued once before the Set Configuration
request, and won't be cleared by the Set Configuration,
Set Interface or ClearFeature (STALL) requests.
Only warm reset, hot reset, set Address 0 clears the exit latencies.
See USB 3.2 section 9.4.14 Table 9-10 Device parameters and events
Add udev->lpm_devinit_allow, and set it if SET_SEL was successful.
If not set, then don't try to enable device initiated LPM
We used to issue a SET_SEL request every time lpm is enabled for either
U1 or U2 link states, meaning a SET_SEL was issued twice after every
Set Configuration and Set Interface requests, easily accumulating to
over 15 SET_SEL requets during a USB3 webcam enumeration.
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20220506161807.3369439-1-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include/linux/usb.h')
| -rw-r--r-- | include/linux/usb.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/include/linux/usb.h b/include/linux/usb.h index 60bee864d897..f7a9914fc97f 100644 --- a/include/linux/usb.h +++ b/include/linux/usb.h @@ -584,6 +584,7 @@ struct usb3_lpm_parameters { * @authenticated: Crypto authentication passed * @wusb: device is Wireless USB * @lpm_capable: device supports LPM + * @lpm_devinit_allow: Allow USB3 device initiated LPM, exit latency is in range * @usb2_hw_lpm_capable: device can perform USB2 hardware LPM * @usb2_hw_lpm_besl_capable: device can perform USB2 hardware BESL LPM * @usb2_hw_lpm_enabled: USB2 hardware LPM is enabled @@ -666,6 +667,7 @@ struct usb_device { unsigned authenticated:1; unsigned wusb:1; unsigned lpm_capable:1; + unsigned lpm_devinit_allow:1; unsigned usb2_hw_lpm_capable:1; unsigned usb2_hw_lpm_besl_capable:1; unsigned usb2_hw_lpm_enabled:1; |