soc: qcom: pmic_glink_altmode: Fix SVID=DP && unconnected edge case

The commit referenced in Fixes started evaluating the value of
alt_port->mux_ctrl before checking the active SVID. This led to
drm_aux_hpd_bridge_notify() no longer being called for the 'DP unplug'
case.

Perhaps somewhat interestingly, the firmware sends a notification with
SVID=DP, mux_ctrl=MUX_CTRL_STATE_NO_CONN and pin_assignment=0 on
unplug. 'pin_assignment' was previously interpreted as a bitfield
excerpt from the second byte of the DP pg_altmode payload (and stored
as an u8).

That value is used in pmic_glink_altmode_sc8280xp_notify(), decremented
by 1 (DPAM_HPD_A). Previously, this would result in an u8 underflow
that would rollover to 0xff (which prior to the Fixes patch would have
caused a pmic_glink_altmode_safe() and 'disconnected' bridge
notification). That check was removed, without a replacement.

Resolve this issue by making sure the SID=DP && mux_ctrl=NO_CONN combo
once again results in a HPD bridge notification.

Fixes: 0539c5a6fdef ("soc: qcom: pmic_glink_altmode: Consume TBT3/USB4 mode notifications")
Reported-by: Abel Vesa <abel.vesa@oss.qualcomm.com>
Tested-by: Abel Vesa <abel.vesa@oss.qualcomm.com>
Signed-off-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
Link: https://lore.kernel.org/r/20260306-topic-pgaltmode_fixup-v1-1-ec154b2d8e89@oss.qualcomm.com
Signed-off-by: Bjorn Andersson <andersson@kernel.org>

diff --git a/drivers/soc/qcom/pmic_glink_altmode.c b/drivers/soc/qcom/pmic_glink_altmode.c
index d0afdcb96ee11862d6402c68dfcd071cf6aa0b02..b496b88842a27ec79eafd52382a140a46634d252 100644 (file)
--- a/drivers/soc/qcom/pmic_glink_altmode.c
+++ b/drivers/soc/qcom/pmic_glink_altmode.c
@@ -350,15 +350,17 @@ static void pmic_glink_altmode_worker(struct work_struct *work)
 
        typec_switch_set(alt_port->typec_switch, alt_port->orientation);
 
-       if (alt_port->mux_ctrl == MUX_CTRL_STATE_NO_CONN) {
-               pmic_glink_altmode_safe(altmode, alt_port);
-       } else if (alt_port->svid == USB_TYPEC_TBT_SID) {
+       if (alt_port->svid == USB_TYPEC_TBT_SID) {
                pmic_glink_altmode_enable_tbt(altmode, alt_port);
        } else if (alt_port->svid == USB_TYPEC_DP_SID) {
-               pmic_glink_altmode_enable_dp(altmode, alt_port,
-                                            alt_port->mode,
-                                            alt_port->hpd_state,
-                                            alt_port->hpd_irq);
+               if (alt_port->mux_ctrl == MUX_CTRL_STATE_NO_CONN) {
+                       pmic_glink_altmode_safe(altmode, alt_port);
+               } else {
+                       pmic_glink_altmode_enable_dp(altmode, alt_port,
+                                                    alt_port->mode,
+                                                    alt_port->hpd_state,
+                                                    alt_port->hpd_irq);
+               }
 
                if (alt_port->hpd_state)
                        conn_status = connector_status_connected;
@@ -368,6 +370,8 @@ static void pmic_glink_altmode_worker(struct work_struct *work)
                drm_aux_hpd_bridge_notify(&alt_port->bridge->dev, conn_status);
        } else if (alt_port->mux_ctrl == MUX_CTRL_STATE_TUNNELING) {
                pmic_glink_altmode_enable_usb4(altmode, alt_port);
+       } else if (alt_port->mux_ctrl == MUX_CTRL_STATE_NO_CONN) {
+               pmic_glink_altmode_safe(altmode, alt_port);
        } else {
                pmic_glink_altmode_enable_usb(altmode, alt_port);
        }