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[PATCH v5 5/7] usb: typec: Introduce mode_selection bit

Andrei Kuchynski posted 7 patches 3 weeks ago
[PATCH v5 5/7] usb: typec: Introduce mode_selection bit
Posted by Andrei Kuchynski 3 weeks ago 
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 <akuchynski@chromium.org>
---
 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 d96ab106a980b..d185688a16b13 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 6eadf7835f8f6..c4c5da6154da9 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 a48c447125184..dbba53f024977 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 dbb259d885266..d61ec38216fa9 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 70026f5f8f997..0513d333b7977 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;
-- 
2.52.0.457.g6b5491de43-goog
Re: [PATCH v5 5/7] usb: typec: Introduce mode_selection bit
Posted by Heikki Krogerus 2 weeks, 6 days ago 
Mon, Jan 19, 2026 at 01:18:22PM +0000, Andrei Kuchynski kirjoitti:
> 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 <akuchynski@chromium.org>

Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>

> ---
>  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 d96ab106a980b..d185688a16b13 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 6eadf7835f8f6..c4c5da6154da9 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 a48c447125184..dbba53f024977 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 dbb259d885266..d61ec38216fa9 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 70026f5f8f997..0513d333b7977 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;
> -- 
> 2.52.0.457.g6b5491de43-goog

-- 
heikki

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