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Commit 9a8ccbc6 authored by Oliver Neukum's avatar Oliver Neukum Committed by Greg Kroah-Hartman
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USB: hub: check for alternate port before enabling A_ALT_HNP_SUPPORT

commit f17c34ff

 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: default avatarOliver Neukum <oneukum@suse.com>
Cc: stable <stable@kernel.org>
Fixes: 7d2d641c

 ("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: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 9d07bdbf
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