usb: hub: Per-port setting to use old enumeration scheme
The "old" enumeration scheme is considerably faster (it takes ~244ms instead of ~356ms to get the descriptor). It is currently only possible to use the old scheme globally (/sys/module/usbcore/parameters/old_scheme_first), which is not desirable as the new scheme was introduced to increase compatibility with more devices. However, in our case, we care about time-to-active for a specific USB device (which we make the firmware for), on a specific port (that is pogo-pin based: not a standard USB port). This new sysfs option makes it possible to use the old scheme on a single port only. Signed-off-by: Nicolas Boichat <drinkcat@chromium.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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@ -189,6 +189,24 @@ Description:
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The file will read "hotplug", "wired" and "not used" if the
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information is available, and "unknown" otherwise.
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What: /sys/bus/usb/devices/.../(hub interface)/portX/quirks
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Date: May 2018
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Contact: Nicolas Boichat <drinkcat@chromium.org>
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Description:
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In some cases, we care about time-to-active for devices
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connected on a specific port (e.g. non-standard USB port like
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pogo pins), where the device to be connected is known in
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advance, and behaves well according to the specification.
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This attribute is a bit-field that controls the behavior of
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a specific port:
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- Bit 0 of this field selects the "old" enumeration scheme,
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as it is considerably faster (it only causes one USB reset
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instead of 2).
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The old enumeration scheme can also be selected globally
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using /sys/module/usbcore/parameters/old_scheme_first, but
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it is often not desirable as the new scheme was introduced to
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increase compatibility with more devices.
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What: /sys/bus/usb/devices/.../(hub interface)/portX/over_current_count
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Date: February 2018
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Contact: Richard Leitner <richard.leitner@skidata.com>
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@ -2636,7 +2636,7 @@ static unsigned hub_is_wusb(struct usb_hub *hub)
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#define SET_ADDRESS_TRIES 2
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#define GET_DESCRIPTOR_TRIES 2
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#define SET_CONFIG_TRIES (2 * (use_both_schemes + 1))
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#define USE_NEW_SCHEME(i) ((i) / 2 == (int)old_scheme_first)
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#define USE_NEW_SCHEME(i, scheme) ((i) / 2 == (int)scheme)
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#define HUB_ROOT_RESET_TIME 60 /* times are in msec */
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#define HUB_SHORT_RESET_TIME 10
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@ -2651,12 +2651,16 @@ static unsigned hub_is_wusb(struct usb_hub *hub)
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* enumeration failures, so disable this enumeration scheme for USB3
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* devices.
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*/
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static bool use_new_scheme(struct usb_device *udev, int retry)
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static bool use_new_scheme(struct usb_device *udev, int retry,
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struct usb_port *port_dev)
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{
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int old_scheme_first_port =
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port_dev->quirks & USB_PORT_QUIRK_OLD_SCHEME;
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if (udev->speed >= USB_SPEED_SUPER)
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return false;
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return USE_NEW_SCHEME(retry);
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return USE_NEW_SCHEME(retry, old_scheme_first_port || old_scheme_first);
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}
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/* Is a USB 3.0 port in the Inactive or Compliance Mode state?
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@ -4392,6 +4396,7 @@ hub_port_init(struct usb_hub *hub, struct usb_device *udev, int port1,
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{
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struct usb_device *hdev = hub->hdev;
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struct usb_hcd *hcd = bus_to_hcd(hdev->bus);
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struct usb_port *port_dev = hub->ports[port1 - 1];
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int retries, operations, retval, i;
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unsigned delay = HUB_SHORT_RESET_TIME;
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enum usb_device_speed oldspeed = udev->speed;
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@ -4513,7 +4518,7 @@ hub_port_init(struct usb_hub *hub, struct usb_device *udev, int port1,
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for (retries = 0; retries < GET_DESCRIPTOR_TRIES; (++retries, msleep(100))) {
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bool did_new_scheme = false;
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if (use_new_scheme(udev, retry_counter)) {
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if (use_new_scheme(udev, retry_counter, port_dev)) {
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struct usb_device_descriptor *buf;
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int r = 0;
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@ -98,6 +98,7 @@ struct usb_port {
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struct mutex status_lock;
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u32 over_current_count;
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u8 portnum;
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u32 quirks;
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unsigned int is_superspeed:1;
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unsigned int usb3_lpm_u1_permit:1;
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unsigned int usb3_lpm_u2_permit:1;
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@ -50,6 +50,28 @@ static ssize_t over_current_count_show(struct device *dev,
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}
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static DEVICE_ATTR_RO(over_current_count);
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static ssize_t quirks_show(struct device *dev,
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struct device_attribute *attr, char *buf)
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{
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struct usb_port *port_dev = to_usb_port(dev);
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return sprintf(buf, "%08x\n", port_dev->quirks);
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}
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static ssize_t quirks_store(struct device *dev, struct device_attribute *attr,
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const char *buf, size_t count)
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{
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struct usb_port *port_dev = to_usb_port(dev);
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u32 value;
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if (kstrtou32(buf, 16, &value))
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return -EINVAL;
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port_dev->quirks = value;
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return count;
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}
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static DEVICE_ATTR_RW(quirks);
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static ssize_t usb3_lpm_permit_show(struct device *dev,
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struct device_attribute *attr, char *buf)
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{
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@ -118,6 +140,7 @@ static DEVICE_ATTR_RW(usb3_lpm_permit);
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static struct attribute *port_dev_attrs[] = {
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&dev_attr_connect_type.attr,
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&dev_attr_quirks.attr,
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&dev_attr_over_current_count.attr,
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NULL,
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};
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@ -489,6 +489,13 @@ enum usb_port_connect_type {
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USB_PORT_NOT_USED,
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};
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/*
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* USB port quirks.
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*/
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/* For the given port, prefer the old (faster) enumeration scheme. */
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#define USB_PORT_QUIRK_OLD_SCHEME BIT(0)
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/*
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* USB 2.0 Link Power Management (LPM) parameters.
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*/
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