This patch introduces a priority sysfs attribute to the USB Type-C
alternate mode port interface. This new attribute allows user-space to
configure the numeric priority of alternate modes managing their preferred
order of operation.
Signed-off-by: Andrei Kuchynski <akuchynski@chromium.org>
---
Documentation/ABI/testing/sysfs-class-typec | 11 +++++++
drivers/usb/typec/class.c | 32 ++++++++++++++++++++-
2 files changed, 42 insertions(+), 1 deletion(-)
diff --git a/Documentation/ABI/testing/sysfs-class-typec b/Documentation/ABI/testing/sysfs-class-typec
index 38e101c17a00..dab3e4e727b6 100644
--- a/Documentation/ABI/testing/sysfs-class-typec
+++ b/Documentation/ABI/testing/sysfs-class-typec
@@ -162,6 +162,17 @@ Description: Lists the supported USB Modes. The default USB mode that is used
- usb3 (USB 3.2)
- usb4 (USB4)
+ What: /sys/class/typec/<port>/<alt-mode>/priority
+Date: July 2025
+Contact: Andrei Kuchynski <akuchynski@chromium.org>
+Description:
+ Displays and allows setting the priority for a specific alt-mode.
+ When read, it shows the current integer priority value. Lower numerical
+ values indicate higher priority (0 is the highest priority).
+ If the new value is already in use by another mode, the priority of the
+ conflicting mode and any subsequent modes will be incremented until they
+ are all unique.
+
USB Type-C partner devices (eg. /sys/class/typec/port0-partner/)
What: /sys/class/typec/<port>-partner/accessory_mode
diff --git a/drivers/usb/typec/class.c b/drivers/usb/typec/class.c
index 9f86605ce125..aaab2e1e98b4 100644
--- a/drivers/usb/typec/class.c
+++ b/drivers/usb/typec/class.c
@@ -19,6 +19,7 @@
#include "bus.h"
#include "class.h"
#include "pd.h"
+#include "mode_selection.h"
static DEFINE_IDA(typec_index_ida);
@@ -445,11 +446,34 @@ svid_show(struct device *dev, struct device_attribute *attr, char *buf)
}
static DEVICE_ATTR_RO(svid);
+static ssize_t priority_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t size)
+{
+ unsigned int val;
+ int err = kstrtouint(buf, 10, &val);
+
+ if (!err) {
+ typec_mode_set_priority(to_typec_altmode(dev), val);
+ return size;
+ }
+
+ return err;
+}
+
+static ssize_t priority_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ return sprintf(buf, "%u\n", to_typec_altmode(dev)->priority);
+}
+static DEVICE_ATTR_RW(priority);
+
static struct attribute *typec_altmode_attrs[] = {
&dev_attr_active.attr,
&dev_attr_mode.attr,
&dev_attr_svid.attr,
&dev_attr_vdo.attr,
+ &dev_attr_priority.attr,
NULL
};
@@ -459,11 +483,15 @@ static umode_t typec_altmode_attr_is_visible(struct kobject *kobj,
struct typec_altmode *adev = to_typec_altmode(kobj_to_dev(kobj));
struct typec_port *port = typec_altmode2port(adev);
- if (attr == &dev_attr_active.attr)
+ if (attr == &dev_attr_active.attr) {
if (!is_typec_port(adev->dev.parent)) {
if (!port->mode_control || !adev->ops || !adev->ops->activate)
return 0444;
}
+ } else if (attr == &dev_attr_priority.attr) {
+ if (!is_typec_port(adev->dev.parent) || !port->mode_control)
+ return 0;
+ }
return attr->mode;
}
@@ -2491,6 +2519,8 @@ typec_port_register_altmode(struct typec_port *port,
to_altmode(adev)->retimer = retimer;
}
+ typec_mode_set_priority(adev, 0);
+
return adev;
}
EXPORT_SYMBOL_GPL(typec_port_register_altmode);
--
2.51.0.rc2.233.g662b1ed5c5-googOn Mon, Aug 25, 2025 at 02:57:50PM +0000, Andrei Kuchynski wrote:
> This patch introduces a priority sysfs attribute to the USB Type-C
> alternate mode port interface. This new attribute allows user-space to
> configure the numeric priority of alternate modes managing their preferred
> order of operation.
>
> Signed-off-by: Andrei Kuchynski <akuchynski@chromium.org>
> ---
> Documentation/ABI/testing/sysfs-class-typec | 11 +++++++
> drivers/usb/typec/class.c | 32 ++++++++++++++++++++-
Maybe patch 4/5 could be squashed into this patch, and I'm wondering
would it make sense to just keep the typec_mode_set_priority() in this
file (drivers/usb/typec/class.c).
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
> 2 files changed, 42 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/ABI/testing/sysfs-class-typec b/Documentation/ABI/testing/sysfs-class-typec
> index 38e101c17a00..dab3e4e727b6 100644
> --- a/Documentation/ABI/testing/sysfs-class-typec
> +++ b/Documentation/ABI/testing/sysfs-class-typec
> @@ -162,6 +162,17 @@ Description: Lists the supported USB Modes. The default USB mode that is used
> - usb3 (USB 3.2)
> - usb4 (USB4)
>
> + What: /sys/class/typec/<port>/<alt-mode>/priority
> +Date: July 2025
> +Contact: Andrei Kuchynski <akuchynski@chromium.org>
> +Description:
> + Displays and allows setting the priority for a specific alt-mode.
> + When read, it shows the current integer priority value. Lower numerical
> + values indicate higher priority (0 is the highest priority).
> + If the new value is already in use by another mode, the priority of the
> + conflicting mode and any subsequent modes will be incremented until they
> + are all unique.
> +
> USB Type-C partner devices (eg. /sys/class/typec/port0-partner/)
>
> What: /sys/class/typec/<port>-partner/accessory_mode
> diff --git a/drivers/usb/typec/class.c b/drivers/usb/typec/class.c
> index 9f86605ce125..aaab2e1e98b4 100644
> --- a/drivers/usb/typec/class.c
> +++ b/drivers/usb/typec/class.c
> @@ -19,6 +19,7 @@
> #include "bus.h"
> #include "class.h"
> #include "pd.h"
> +#include "mode_selection.h"
>
> static DEFINE_IDA(typec_index_ida);
>
> @@ -445,11 +446,34 @@ svid_show(struct device *dev, struct device_attribute *attr, char *buf)
> }
> static DEVICE_ATTR_RO(svid);
>
> +static ssize_t priority_store(struct device *dev,
> + struct device_attribute *attr,
> + const char *buf, size_t size)
> +{
> + unsigned int val;
> + int err = kstrtouint(buf, 10, &val);
> +
> + if (!err) {
> + typec_mode_set_priority(to_typec_altmode(dev), val);
> + return size;
> + }
> +
> + return err;
> +}
> +
> +static ssize_t priority_show(struct device *dev,
> + struct device_attribute *attr, char *buf)
> +{
> + return sprintf(buf, "%u\n", to_typec_altmode(dev)->priority);
> +}
> +static DEVICE_ATTR_RW(priority);
> +
> static struct attribute *typec_altmode_attrs[] = {
> &dev_attr_active.attr,
> &dev_attr_mode.attr,
> &dev_attr_svid.attr,
> &dev_attr_vdo.attr,
> + &dev_attr_priority.attr,
> NULL
> };
>
> @@ -459,11 +483,15 @@ static umode_t typec_altmode_attr_is_visible(struct kobject *kobj,
> struct typec_altmode *adev = to_typec_altmode(kobj_to_dev(kobj));
> struct typec_port *port = typec_altmode2port(adev);
>
> - if (attr == &dev_attr_active.attr)
> + if (attr == &dev_attr_active.attr) {
> if (!is_typec_port(adev->dev.parent)) {
> if (!port->mode_control || !adev->ops || !adev->ops->activate)
> return 0444;
> }
> + } else if (attr == &dev_attr_priority.attr) {
> + if (!is_typec_port(adev->dev.parent) || !port->mode_control)
> + return 0;
> + }
>
> return attr->mode;
> }
> @@ -2491,6 +2519,8 @@ typec_port_register_altmode(struct typec_port *port,
> to_altmode(adev)->retimer = retimer;
> }
>
> + typec_mode_set_priority(adev, 0);
> +
> return adev;
> }
> EXPORT_SYMBOL_GPL(typec_port_register_altmode);
> --
> 2.51.0.rc2.233.g662b1ed5c5-goog
>
--
heikki
On Fri, Sep 5, 2025 at 12:34 PM Heikki Krogerus <heikki.krogerus@linux.intel.com> wrote: > > On Mon, Aug 25, 2025 at 02:57:50PM +0000, Andrei Kuchynski wrote: > > This patch introduces a priority sysfs attribute to the USB Type-C > > alternate mode port interface. This new attribute allows user-space to > > configure the numeric priority of alternate modes managing their preferred > > order of operation. > > > > Signed-off-by: Andrei Kuchynski <akuchynski@chromium.org> > > --- > > Documentation/ABI/testing/sysfs-class-typec | 11 +++++++ > > drivers/usb/typec/class.c | 32 ++++++++++++++++++++- > > Maybe patch 4/5 could be squashed into this patch, and I'm wondering > would it make sense to just keep the typec_mode_set_priority() in this > file (drivers/usb/typec/class.c). > > Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com> > > -- > heikki You're right, mode_selection.c is quite empty now. However, in the next series, it will be the only user of the priority variable. So I'd prefer to keep it there, if you don’t mind. I think putting it in class.c would create a mess. Thank you for the review! Andrei
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