From be727d4000669a64a3ce6697669150d78bb2d492 Mon Sep 17 00:00:00 2001 From: Andrei Kuchynski Date: Mon, 19 Jan 2026 13:18:22 +0000 Subject: [PATCH] usb: typec: Introduce mode_selection bit The port driver sets this bit for an alternate mode description to indicate support for the mode selection feature. Once set, individual Alt Mode drivers will no longer attempt to activate their respective modes within their probe functions. This prevents race conditions and non-prioritized activation. The bit is not set by default. If left unset, the system retains the current behavior where Alt Mode drivers manage their own activation logic. Signed-off-by: Andrei Kuchynski Reviewed-by: Heikki Krogerus Link: https://patch.msgid.link/20260119131824.2529334-6-akuchynski@chromium.org Signed-off-by: Greg Kroah-Hartman --- drivers/usb/typec/altmodes/displayport.c | 6 ++++-- drivers/usb/typec/altmodes/thunderbolt.c | 2 +- drivers/usb/typec/class.c | 1 + include/linux/usb/typec.h | 1 + include/linux/usb/typec_altmode.h | 1 + 5 files changed, 8 insertions(+), 3 deletions(-) diff --git a/drivers/usb/typec/altmodes/displayport.c b/drivers/usb/typec/altmodes/displayport.c index d96ab106a980..d185688a16b1 100644 --- a/drivers/usb/typec/altmodes/displayport.c +++ b/drivers/usb/typec/altmodes/displayport.c @@ -804,8 +804,10 @@ int dp_altmode_probe(struct typec_altmode *alt) if (plug) typec_altmode_set_drvdata(plug, dp); - dp->state = plug ? DP_STATE_ENTER_PRIME : DP_STATE_ENTER; - schedule_work(&dp->work); + if (!alt->mode_selection) { + dp->state = plug ? DP_STATE_ENTER_PRIME : DP_STATE_ENTER; + schedule_work(&dp->work); + } return 0; } diff --git a/drivers/usb/typec/altmodes/thunderbolt.c b/drivers/usb/typec/altmodes/thunderbolt.c index 6eadf7835f8f..c4c5da6154da 100644 --- a/drivers/usb/typec/altmodes/thunderbolt.c +++ b/drivers/usb/typec/altmodes/thunderbolt.c @@ -307,7 +307,7 @@ static int tbt_altmode_probe(struct typec_altmode *alt) typec_altmode_set_drvdata(alt, tbt); typec_altmode_set_ops(alt, &tbt_altmode_ops); - if (tbt_ready(alt)) { + if (!alt->mode_selection && tbt_ready(alt)) { if (tbt->plug[TYPEC_PLUG_SOP_P]) tbt->state = TBT_STATE_SOP_P_ENTER; else if (tbt->plug[TYPEC_PLUG_SOP_PP]) diff --git a/drivers/usb/typec/class.c b/drivers/usb/typec/class.c index a48c44712518..dbba53f02497 100644 --- a/drivers/usb/typec/class.c +++ b/drivers/usb/typec/class.c @@ -655,6 +655,7 @@ typec_register_altmode(struct device *parent, alt->adev.svid = desc->svid; alt->adev.mode = desc->mode; alt->adev.vdo = desc->vdo; + alt->adev.mode_selection = desc->mode_selection; alt->roles = desc->roles; alt->id = id; diff --git a/include/linux/usb/typec.h b/include/linux/usb/typec.h index dbb259d88526..d61ec38216fa 100644 --- a/include/linux/usb/typec.h +++ b/include/linux/usb/typec.h @@ -155,6 +155,7 @@ struct typec_altmode_desc { /* Only used with ports */ enum typec_port_data roles; bool inactive; + bool mode_selection; }; void typec_partner_set_pd_revision(struct typec_partner *partner, u16 pd_revision); diff --git a/include/linux/usb/typec_altmode.h b/include/linux/usb/typec_altmode.h index 70026f5f8f99..0513d333b797 100644 --- a/include/linux/usb/typec_altmode.h +++ b/include/linux/usb/typec_altmode.h @@ -37,6 +37,7 @@ struct typec_altmode { u32 vdo; unsigned int active:1; u8 priority; + bool mode_selection; char *desc; const struct typec_altmode_ops *ops; -- 2.47.3