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[PATCH v3 5/5] usb: typec: Expose alternate mode priority via sysfs

Andrei Kuchynski posted 5 patches 5 months, 1 week ago
There is a newer version of this series
[PATCH v3 5/5] usb: typec: Expose alternate mode priority via sysfs
Posted by Andrei Kuchynski 5 months, 1 week ago 
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>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
---
 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);
-- 
2.51.0.355.g5224444f11-goog
Re: [PATCH v3 5/5] usb: typec: Expose alternate mode priority via sysfs
Posted by Greg Kroah-Hartman 5 months ago 
On Fri, Sep 05, 2025 at 02:22:06PM +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>
> Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
> ---
>  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.

What is the units here?  0 is highest, what is the lowest?  What is the
range here?  I can't determine this from the text, sorry.

> +
>  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);

For new sysfs files, please use sysfs_emit(), otherwise someone will
come along with a janitorial patch to fix it up after it lands in the
tree :)

thanks,

greg k-h
Re: [PATCH v3 5/5] usb: typec: Expose alternate mode priority via sysfs
Posted by Andrei Kuchynski 5 months ago 
On Wed, Sep 10, 2025 at 1:28 PM Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> On Fri, Sep 05, 2025 at 02:22:06PM +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>
> > Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
> > ---
> >  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.
>
> What is the units here?  0 is highest, what is the lowest?  What is the
> range here?  I can't determine this from the text, sorry.
>

Hi Greg,

You are right, the lowest range is not specified; the only note is that
the value should be an integer of 0 or higher.
The mode selection algorithm does not impose a maximum value. It
operates with any priority values returned by kstrtouint(). Any MAX
value would require an explanation as to why that specific value is
the maximum, and I do not have such an explanation. The only
restriction is that it must fit within an unsigned int variable, which
is checked by kstrtouint() against UINT_MAX.

> > +
> >  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);
>
> For new sysfs files, please use sysfs_emit(), otherwise someone will
> come along with a janitorial patch to fix it up after it lands in the
> tree :)
>
> thanks,
>
> greg k-h

I will change it, sysfs_emit instead of sprintf.
Thanks!


Andrei

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