From: Pablo Sun pablo.sun@mediatek.com
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 | 4 ++-- include/linux/usb/typec_dp.h | 5 +++++ 2 files changed, 7 insertions(+), 2 deletions(-)
--- a/drivers/usb/typec/altmodes/displayport.c +++ b/drivers/usb/typec/altmodes/displayport.c @@ -88,8 +88,8 @@ static int dp_altmode_configure(struct d case DP_STATUS_CON_UFP_D: case DP_STATUS_CON_BOTH: /* NOTE: First acting as DP source */ conf |= DP_CONF_UFP_U_AS_UFP_D; - pin_assign = DP_CAP_DFP_D_PIN_ASSIGN(dp->alt->vdo) & - DP_CAP_UFP_D_PIN_ASSIGN(dp->port->vdo); + pin_assign = DP_CAP_PIN_ASSIGN_UFP_D(dp->alt->vdo) & + DP_CAP_PIN_ASSIGN_DFP_D(dp->port->vdo); break; default: break; --- a/include/linux/usb/typec_dp.h +++ b/include/linux/usb/typec_dp.h @@ -73,6 +73,11 @@ enum { #define DP_CAP_USB BIT(7) #define DP_CAP_DFP_D_PIN_ASSIGN(_cap_) (((_cap_) & GENMASK(15, 8)) >> 8) #define DP_CAP_UFP_D_PIN_ASSIGN(_cap_) (((_cap_) & GENMASK(23, 16)) >> 16) +/* Get pin assignment taking plug & receptacle into consideration */ +#define DP_CAP_PIN_ASSIGN_UFP_D(_cap_) ((_cap_ & DP_CAP_RECEPTACLE) ? \ + DP_CAP_UFP_D_PIN_ASSIGN(_cap_) : DP_CAP_DFP_D_PIN_ASSIGN(_cap_)) +#define DP_CAP_PIN_ASSIGN_DFP_D(_cap_) ((_cap_ & DP_CAP_RECEPTACLE) ? \ + DP_CAP_DFP_D_PIN_ASSIGN(_cap_) : DP_CAP_UFP_D_PIN_ASSIGN(_cap_))
/* DisplayPort Status Update VDO bits */ #define DP_STATUS_CONNECTION(_status_) ((_status_) & 3)