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xhci: dbc: allow setting manufacturer string through sysfs

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Add dbc_manufacturer sysfs attribute to allow changing the manufacturer
description presented by the debug device when a host requests a string
descriptor with iManufacturer index.

Value can only be changed while debug capability (DbC) is in disabled
state to prevent USB device descriptor change while connected to a USB
host.

The default value is "Linux Foundation".
The string length can be from 1 to 126 characters.
String is terminated at null or newline, driver does not support empty
string.

[ mn: Improve commit message and sysfs entry documentation ]

Signed-off-by: Łukasz Bartosik <ukaszb@chromium.org>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://patch.msgid.link/20260120181148.128712-5-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Łukasz Bartosik 2026-01-20 20:11:48 +02:00 • committed by Greg Kroah-Hartman
parent 33d15312e3
commit db7fd1955e
2 changed files with 49 additions and 0 deletions
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13
Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd
View file

@ -114,3 +114,16 @@ Description:
connected to a USB host.
The default value is "Linux USB Debug Target".
The field length can be from 1 to 126 characters.
What: /sys/bus/pci/drivers/xhci_hcd/.../dbc_manufacturer
Date: January 2026
Contact: Łukasz Bartosik <ukaszb@chromium.org>
Description:
The dbc_manufacturer attribute allows to change the manufacturer
string descriptor presented by the debug device when a host
requests a string descriptor with iManufacturer index.
Value can only be changed while debug capability (DbC) is in
disabled state to prevent USB device descriptor change while
connected to a USB host.
The default value is "Linux Foundation".
The field length can be from 1 to 126 characters.

36
drivers/usb/host/xhci-dbgcap.c
View file

@ -1210,6 +1210,40 @@ static ssize_t dbc_bcdDevice_store(struct device *dev,
return size;
}
static ssize_t dbc_manufacturer_show(struct device *dev,
struct device_attribute *attr,
char *buf)
{
struct xhci_hcd *xhci = hcd_to_xhci(dev_get_drvdata(dev));
struct xhci_dbc *dbc = xhci->dbc;
return sysfs_emit(buf, "%s\n", dbc->str.manufacturer);
}
static ssize_t dbc_manufacturer_store(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t size)
{
struct xhci_hcd *xhci = hcd_to_xhci(dev_get_drvdata(dev));
struct xhci_dbc *dbc = xhci->dbc;
size_t len;
if (dbc->state != DS_DISABLED)
return -EBUSY;
len = strcspn(buf, "\n");
if (!len)
return -EINVAL;
if (len > USB_MAX_STRING_LEN)
return -E2BIG;
memcpy(dbc->str.manufacturer, buf, len);
dbc->str.manufacturer[len] = '\0';
return size;
}
static ssize_t dbc_product_show(struct device *dev,
struct device_attribute *attr,
char *buf)
@ -1367,6 +1401,7 @@ static DEVICE_ATTR_RW(dbc_idProduct);
static DEVICE_ATTR_RW(dbc_bcdDevice);
static DEVICE_ATTR_RW(dbc_serial);
static DEVICE_ATTR_RW(dbc_product);
static DEVICE_ATTR_RW(dbc_manufacturer);
static DEVICE_ATTR_RW(dbc_bInterfaceProtocol);
static DEVICE_ATTR_RW(dbc_poll_interval_ms);
@ -1377,6 +1412,7 @@ static struct attribute *dbc_dev_attrs[] = {
&dev_attr_dbc_bcdDevice.attr,
&dev_attr_dbc_serial.attr,
&dev_attr_dbc_product.attr,
&dev_attr_dbc_manufacturer.attr,
&dev_attr_dbc_bInterfaceProtocol.attr,
&dev_attr_dbc_poll_interval_ms.attr,
NULL