]> git.ipfire.org Git - thirdparty/kernel/stable.git/commit
USB: hub: check for alternate port before enabling A_ALT_HNP_SUPPORT
authorOliver Neukum <oneukum@suse.com>
Mon, 22 Jan 2024 15:35:32 +0000 (16:35 +0100)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Fri, 23 Feb 2024 08:24:56 +0000 (09:24 +0100)
commiteafeda9ee9c00515ddf717a019b19f28637352fb
treea3dc58953f827ba868570d504936ebcb4f1194e6
parentec68d8d25b8469882fc9c484cc6b0d88b025971e
USB: hub: check for alternate port before enabling A_ALT_HNP_SUPPORT

commit f17c34ffc792bbb520e4b61baa16b6cfc7d44b13 upstream.

The OTG 1.3 spec has the feature A_ALT_HNP_SUPPORT, which tells
a device that it is connected to the wrong port. Some devices
refuse to operate if you enable that feature, because it indicates
to them that they ought to request to be connected to another port.

According to the spec this feature may be used based only the following
three conditions:

6.5.3 a_alt_hnp_support
Setting this feature indicates to the B-device that it is connected to
an A-device port that is not capable of HNP, but that the A-device does
have an alternate port that is capable of HNP.
The A-device is required to set this feature under the following conditions:
• the A-device has multiple receptacles
• the A-device port that connects to the B-device does not support HNP
• the A-device has another port that does support HNP

A check for the third and first condition is missing. Add it.

Signed-off-by: Oliver Neukum <oneukum@suse.com>
Cc: stable <stable@kernel.org>
Fixes: 7d2d641c44269 ("usb: otg: don't set a_alt_hnp_support feature for OTG 2.0 device")
Link: https://lore.kernel.org/r/20240122153545.12284-1-oneukum@suse.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/usb/core/hub.c