]> git.itanic.dy.fi Git - linux-stable/commit
usb: typec: altmodes/displayport: correct pin assignment for UFP receptacles
authorPablo Sun <pablo.sun@mediatek.com>
Thu, 4 Aug 2022 03:48:03 +0000 (11:48 +0800)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Thu, 15 Sep 2022 10:04:52 +0000 (12:04 +0200)
commit08f27a242898b0788aa7cf45dff97e5f305347a5
treedb3b3f156ef679a95e19c212ac3c4cee0c5f2b26
parent1abdc68b49c7d77cfd5480d99a1201ae7e5dcf99
usb: typec: altmodes/displayport: correct pin assignment for UFP receptacles

commit c1e5c2f0cb8a22ec2e14af92afc7006491bebabb upstream.

Fix incorrect pin assignment values when connecting to a monitor with
Type-C receptacle instead of a plug.

According to specification, an UFP_D receptacle's pin assignment
should came from the UFP_D pin assignments field (bit 23:16), while
an UFP_D plug's assignments are described in the DFP_D pin assignments
(bit 15:8) during Mode Discovery.

For example the LG 27 UL850-W is a monitor with Type-C receptacle.
The monitor responds to MODE DISCOVERY command with following
DisplayPort Capability flag:

        dp->alt->vdo=0x140045

The existing logic only take cares of UPF_D plug case,
and would take the bit 15:8 for this 0x140045 case.

This results in an non-existing pin assignment 0x0 in
dp_altmode_configure.

To fix this problem a new set of macros are introduced
to take plug/receptacle differences into consideration.

Fixes: 0e3bb7d6894d ("usb: typec: Add driver for DisplayPort alternate mode")
Cc: stable@vger.kernel.org
Co-developed-by: Pablo Sun <pablo.sun@mediatek.com>
Co-developed-by: Macpaul Lin <macpaul.lin@mediatek.com>
Reviewed-by: Guillaume Ranquet <granquet@baylibre.com>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Pablo Sun <pablo.sun@mediatek.com>
Signed-off-by: Macpaul Lin <macpaul.lin@mediatek.com>
Link: https://lore.kernel.org/r/20220804034803.19486-1-macpaul.lin@mediatek.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/usb/typec/altmodes/displayport.c
include/linux/usb/typec_dp.h