Hi,

On 14-03-16 11:18, Stefan Roese wrote:

This patch changes the USB port scanning procedure and timeout handling in the following ways:

a) The power-on delay in usb_hub_power_on() is now reduced to a value of max(100ms, "hub->desc.bPwrOn2PwrGood * 2"). The code does not wait using mdelay in this usb_hub_power_on() will wait before querying the device in the scanning loop later. The total timeout for this hub, which is 1 second + "hub->desc.bPwrOn2PwrGood * 2" is calculated and will be used in the following per-port scanning loop as the timeout to detect active USB devices on this hub.

b) Don't delay the minimum delay (for power to stabalize) in usb_hub_power_on(). Instead skip querying these devices in the scannig loop until the delay time is reached.

c) The ports are now scanned in a quasy parallel way. The current code did wait for each (unconnected) port to reach its timeout. And only then continue with the next port. This patch now changes this to scan all ports of all USB hubs quasi simultaniously. For this, all ports are added to a scanning list. This list is scanned until all ports are ready by either a) reaching the connection timeout (calculated earlier), or by b) detecting a USB device. Resulting in a faster USB scan time as the recursive scanning of USB hubs connected to the hub thats currently being scanned will start earlier.

Without this patch: starting USB... USB0: USB EHCI 1.00 scanning bus 0 for devices... 9 USB Device(s) found

time: 20.163 seconds

With this patch: starting USB... USB0: USB EHCI 1.00 scanning bus 0 for devices... 9 USB Device(s) found

time: 1.822 seconds

So ~18.3 seconds of USB scanning time reduction.

Signed-off-by: Stefan Roese sr@denx.de

---

Changes in v3:

• Introduced scanning list containing all USB devices of one USB controller that need to get scanned
• Don't delay in usb_hub_power_on(). Instead skip querying these devices until the delay time is reached.

Oh I like :)

Changes in v2:

• Remove static USB port configuration patch (for now)

  common/usb_hub.c | 289 +++++++++++++++++++++++++++++++++++++------------------ include/usb.h | 3 + 2 files changed, 200 insertions(+), 92 deletions(-)

diff --git a/common/usb_hub.c b/common/usb_hub.c index d621f50..1167217 100644 --- a/common/usb_hub.c +++ b/common/usb_hub.c @@ -30,6 +30,7 @@ #include <asm/processor.h> #include <asm/unaligned.h> #include <linux/ctype.h> +#include <linux/list.h> #include <asm/byteorder.h> #ifdef CONFIG_SANDBOX #include <asm/state.h> @@ -120,7 +121,21 @@ static void usb_hub_power_on(struct usb_hub_device *hub) pgood_delay = max(pgood_delay, (unsigned)simple_strtol(env, NULL, 0)); debug("pgood_delay=%dms\n", pgood_delay);

• mdelay(pgood_delay + 1000);

• /*

• * Do a minimum delay of the larger value of 100ms or pgood_delay
  

• * so that the power can stablize before the devices are queried
  

• */
  

• dev->query_delay = get_timer(0) + max(100, (int)pgood_delay);

• /*

• * Record the power-on timeout here. The max. delay (timeout)
  

• * will be done based on this value in the USB port loop in
  

• * usb_hub_configure() later.
  

• */
  

• dev->connect_timeout = get_timer(0) + pgood_delay + 1000;

• debug("devnum=%d poweron: query_delay=%d connect_timeout=%d\n",

•      dev->devnum, max(100, (int)pgood_delay), pgood_delay + 1000);
  

  }

  void usb_hub_reset(void)

@@ -332,6 +347,161 @@ int usb_hub_port_connect_change(struct usb_device *dev, int port) return ret; }

+static LIST_HEAD(usb_scan_list);

+struct usb_device_scan {

• struct usb_device *dev; /* USB hub device to scan */
• struct usb_hub_device *hub; /* USB hub struct */
• int port; /* USB port to scan */
• struct list_head list;

+};

+static int usb_scan_port(struct usb_device_scan *usb_scan) +{

• ALLOC_CACHE_ALIGN_BUFFER(struct usb_port_status, portsts, 1);
• unsigned short portstatus;
• unsigned short portchange;
• struct usb_device *dev;
• struct usb_hub_device *hub;
• int ret = 0;
• int i;
• dev = usb_scan->dev;
• hub = usb_scan->hub;
• i = usb_scan->port;

+#ifdef CONFIG_DM_USB

• debug("\n\nScanning '%s' port %d\n", dev->dev->name, i + 1);

+#else

• debug("\n\nScanning port %d\n", i + 1);

+#endif

• ret = usb_get_port_status(dev, i + 1, portsts);
• if (ret < 0) {

• debug("get_port_status failed\n");
  

• return 0;
  

• }
• portstatus = le16_to_cpu(portsts->wPortStatus);
• portchange = le16_to_cpu(portsts->wPortChange);
• /* No connection change happened, wait a bit more. */
• if (!(portchange & USB_PORT_STAT_C_CONNECTION)) {

• if (get_timer(0) >= dev->connect_timeout) {
  

• 	debug("devnum=%d port=%d: timeout\n",
  

• 	      dev->devnum, i + 1);
  

• 	/* Remove this device from scanning list */
  

• 	list_del(&usb_scan->list);
  

• 	return 0;
  

• }
  

• return 0;
  

• }
• /* Test if the connection came up, and if so, exit. */
• if (portstatus & USB_PORT_STAT_CONNECTION) {

• debug("devnum=%d port=%d: USB dev found\n", dev->devnum, i + 1);
  

• /* Remove this device from scanning list */
  

• list_del(&usb_scan->list);
  

• /* A new USB device is ready at this point */
  

• debug("Port %d Status %X Change %X\n",
  

•       i + 1, portstatus, portchange);
  

• if (portchange & USB_PORT_STAT_C_CONNECTION) {
  

• 	debug("port %d connection change\n", i + 1);
  

• 	usb_hub_port_connect_change(dev, i);
  

• }
  

• if (portchange & USB_PORT_STAT_C_ENABLE) {
  

• 	debug("port %d enable change, status %x\n",
  

• 	      i + 1, portstatus);
  

• 	usb_clear_port_feature(dev, i + 1,
  

• 			       USB_PORT_FEAT_C_ENABLE);
  

• 	/*
  

• 	 * The following hack causes a ghost device problem
  

• 	 * to Faraday EHCI
  

• 	 */
  

+#ifndef CONFIG_USB_EHCI_FARADAY

• 	/* EM interference sometimes causes bad shielded USB
  

• 	 * devices to be shutdown by the hub, this hack enables
  

• 	 * them again. Works at least with mouse driver */
  

• 	if (!(portstatus & USB_PORT_STAT_ENABLE) &&
  

• 	    (portstatus & USB_PORT_STAT_CONNECTION) &&
  

• 	    usb_device_has_child_on_port(dev, i)) {
  

• 		debug("already running port %i disabled by hub (EMI?), re-enabling...\n",
  

• 		      i + 1);
  

• 		usb_hub_port_connect_change(dev, i);
  

• 	}
  

+#endif

• }
  

• if (portstatus & USB_PORT_STAT_SUSPEND) {
  

• 	debug("port %d suspend change\n", i + 1);
  

• 	usb_clear_port_feature(dev, i + 1,
  

• 			       USB_PORT_FEAT_SUSPEND);
  

• }
  

• if (portchange & USB_PORT_STAT_C_OVERCURRENT) {
  

• 	debug("port %d over-current change\n", i + 1);
  

• 	usb_clear_port_feature(dev, i + 1,
  

• 			       USB_PORT_FEAT_C_OVER_CURRENT);
  

• 	usb_hub_power_on(hub);
  

• }
  

• if (portchange & USB_PORT_STAT_C_RESET) {
  

• 	debug("port %d reset change\n", i + 1);
  

• 	usb_clear_port_feature(dev, i + 1,
  

• 			       USB_PORT_FEAT_C_RESET);
  

• }
  

• }
• return 0;

+}

+static int usb_device_list_scan(void) +{

• struct usb_device_scan *usb_scan;
• struct usb_device_scan *tmp;
• static int running;
• int ret = 0;
• /* Only run this loop once for each controller */
• if (running)

• return 0;
  

• running = 1;
• while (1) {

• /* We're done, once the list is empty again */
  

• if (list_empty(&usb_scan_list))
  

• 	goto out;
  

• list_for_each_entry_safe(usb_scan, tmp, &usb_scan_list, list) {
  

• 	int ret;
  

• 	/*
  

• 	 * Don't talk to the device before the query delay is
  

• 	 * expired. This is needed for voltages to stabalize.
  

• 	 */
  

• 	if (get_timer(0) < usb_scan->dev->query_delay)
  

• 		continue;
  

I would prefer for this to be moved to usb_scan_port().

• 	/* Scan this port */
  

• 	ret = usb_scan_port(usb_scan);
  

• 	if (ret)
  

• 		goto out;
  

• }
  

• }

+out:

• /*

• * This USB controller has has finished scanning all its connected
  

• * USB devices. Set "running" back to 0, so that other USB controllers
  

• * will scan their devices too.
  

• */
  

• running = 0;
• return ret;

+}

static int usb_hub_configure(struct usb_device *dev) { @@ -466,104 +636,39 @@ static int usb_hub_configure(struct usb_device *dev) for (i = 0; i < dev->maxchild; i++) usb_hub_reset_devices(i + 1);

• for (i = 0; i < dev->maxchild; i++) {

• ALLOC_CACHE_ALIGN_BUFFER(struct usb_port_status, portsts, 1);
  

• unsigned short portstatus, portchange;
  

• int ret;
  

• ulong start = get_timer(0);
  

• uint delay = CONFIG_SYS_HZ;
  

• #ifdef CONFIG_SANDBOX

• if (state_get_skip_delays())
  

• 	delay = 0;
  

-#endif -#ifdef CONFIG_DM_USB

• debug("\n\nScanning '%s' port %d\n", dev->dev->name, i + 1);
  

-#else

• debug("\n\nScanning port %d\n", i + 1);
  

• if (state_get_skip_delays())

• dev->poweron_timeout = 0;
  

  #endif

• /*
  

•  * Wait for (whichever finishes first)
  

•  *  - A maximum of 10 seconds
  

•  *    This is a purely observational value driven by connecting
  

•  *    a few broken pen drives and taking the max * 1.5 approach
  

•  *  - connection_change and connection state to report same
  

•  *    state
  

•  */
  

• do {
  

• 	ret = usb_get_port_status(dev, i + 1, portsts);
  

• 	if (ret < 0) {
  

• 		debug("get_port_status failed\n");
  

• 		break;
  

• 	}
  
  

• 	portstatus = le16_to_cpu(portsts->wPortStatus);
  

• 	portchange = le16_to_cpu(portsts->wPortChange);
  

• 	/* No connection change happened, wait a bit more. */
  

• 	if (!(portchange & USB_PORT_STAT_C_CONNECTION))
  

• 		continue;
  

• 	/* Test if the connection came up, and if so, exit. */
  

• 	if (portstatus & USB_PORT_STAT_CONNECTION)
  

• 		break;
  

• } while (get_timer(start) < delay);
  

• if (ret < 0)
  

• 	continue;
  

• debug("Port %d Status %X Change %X\n",
  

•       i + 1, portstatus, portchange);
  

• if (portchange & USB_PORT_STAT_C_CONNECTION) {
  

• 	debug("port %d connection change\n", i + 1);
  

• 	usb_hub_port_connect_change(dev, i);
  

• }
  

• if (portchange & USB_PORT_STAT_C_ENABLE) {
  

• 	debug("port %d enable change, status %x\n",
  

• 	      i + 1, portstatus);
  

• 	usb_clear_port_feature(dev, i + 1,
  

• 				USB_PORT_FEAT_C_ENABLE);
  

• 	/*
  

• 	 * The following hack causes a ghost device problem
  

• 	 * to Faraday EHCI
  

• 	 */
  

-#ifndef CONFIG_USB_EHCI_FARADAY

• 	/* EM interference sometimes causes bad shielded USB
  

• 	 * devices to be shutdown by the hub, this hack enables
  

• 	 * them again. Works at least with mouse driver */
  

• 	if (!(portstatus & USB_PORT_STAT_ENABLE) &&
  

• 	     (portstatus & USB_PORT_STAT_CONNECTION) &&
  

• 	     usb_device_has_child_on_port(dev, i)) {
  

• 		debug("already running port %i "  \
  

• 		      "disabled by hub (EMI?), " \
  

• 		      "re-enabling...\n", i + 1);
  

• 		      usb_hub_port_connect_change(dev, i);
  

• 	}
  

-#endif

• }
  

• if (portstatus & USB_PORT_STAT_SUSPEND) {
  

• 	debug("port %d suspend change\n", i + 1);
  

• 	usb_clear_port_feature(dev, i + 1,
  

• 				USB_PORT_FEAT_SUSPEND);
  

• }
  

• /*

• * Only add the connected USB devices, including potential hubs,
  

• * to a scanning list. This list will get scanned and devices that
  

• * are detected (either via port connected or via port timeout)
  

• * will get removed from this list. Scanning of the devices on this
  

• * list will continue until all devices are removed.
  

• */
  

• for (i = 0; i < dev->maxchild; i++) {

• struct usb_device_scan *usb_scan;
  
  

• if (portchange & USB_PORT_STAT_C_OVERCURRENT) {
  

• 	debug("port %d over-current change\n", i + 1);
  

• 	usb_clear_port_feature(dev, i + 1,
  

• 				USB_PORT_FEAT_C_OVER_CURRENT);
  

• 	usb_hub_power_on(hub);
  

• usb_scan = calloc(1, sizeof(*usb_scan));
  

• if (!usb_scan) {
  

• 	printf("Can't allocate memory for USB device!\n");
  

• 	return -ENOMEM;
  

  }

• usb_scan->dev = dev;
  

• usb_scan->hub = hub;
  

• usb_scan->port = i;
  

• INIT_LIST_HEAD(&usb_scan->list);
  

This (INIT_LIST_HEAD) is not necessary, as this is not the HEAD of a list, but just a list member, anything set here will immediately be overridden by:

• list_add_tail(&usb_scan->list, &usb_scan_list);
  

This list_add_tail call.

• }

• if (portchange & USB_PORT_STAT_C_RESET) {
  

• 	debug("port %d reset change\n", i + 1);
  

• 	usb_clear_port_feature(dev, i + 1,
  

• 				USB_PORT_FEAT_C_RESET);
  

• }
  

• } /* end for i all ports */

• /*

• * And now call the scanning code which loops over the generated list
  

• */
  

• ret = usb_device_list_scan();

• return 0;

• return ret; }

  static int usb_hub_check(struct usb_device *dev, int ifnum)

diff --git a/include/usb.h b/include/usb.h index 0b410b6..0b57093 100644 --- a/include/usb.h +++ b/include/usb.h @@ -153,6 +153,9 @@ struct usb_device { struct udevice *dev; /* Pointer to associated device */ struct udevice *controller_dev; /* Pointer to associated controller */ #endif

• ulong connect_timeout; /* Device connection timeout in ms */

• ulong query_delay; /* Device query delay in ms */ };

  struct int_queue;

Otherwise I like this patch, in fact I like it a lot :)

With the above things fixed you can add my:

Acked-by: Hans de Goede hdegoede@redhat.com

To it.

I guess this scratches your itch, so you're probably done with this, if not having parallel controller scanning too would be awesome for some boards I've which have up to 8 controllers (of which only 6 are supporte d by u-boot atm, but that is a different issue).

Regards,

Hans

On 03/14/2016 04:18 AM, Stefan Roese wrote:

This patch changes the USB port scanning procedure and timeout handling in the following ways:

A few nits/typos in the description, and some review comments below.

a) The power-on delay in usb_hub_power_on() is now reduced to a value of max(100ms, "hub->desc.bPwrOn2PwrGood * 2"). The code does not wait using mdelay in this usb_hub_power_on() will wait before querying

^^^^^^^^ change to ", instead"? The existing text looks like an editing mistake.

the device in the scanning loop later. The total timeout for this hub, which is 1 second + "hub->desc.bPwrOn2PwrGood * 2" is calculated and will be used in the following per-port scanning loop as the timeout to detect active USB devices on this hub.

b) Don't delay the minimum delay (for power to stabalize) in

stabilize

usb_hub_power_on(). Instead skip querying these devices in the scannig loop until the delay time is reached.

c) The ports are now scanned in a quasy parallel way. The current code did

quasi

wait for each (unconnected) port to reach its timeout. And only then continue with the next port. This patch now changes this to scan all ports of all USB hubs quasi simultaniously. For this, all ports are added

simultaneously

to a scanning list. This list is scanned until all ports are ready by either a) reaching the connection timeout (calculated earlier), or by b) detecting a USB device. Resulting in a faster USB scan time as the recursive scanning of USB hubs connected to the hub thats currently

that's

being scanned will start earlier.

diff --git a/common/usb_hub.c b/common/usb_hub.c

@@ -120,7 +121,21 @@ static void usb_hub_power_on(struct usb_hub_device *hub) pgood_delay = max(pgood_delay, (unsigned)simple_strtol(env, NULL, 0)); debug("pgood_delay=%dms\n", pgood_delay);

• mdelay(pgood_delay + 1000);

• /*

• * Do a minimum delay of the larger value of 100ms or pgood_delay
  

• * so that the power can stablize before the devices are queried
  

• */
  

• dev->query_delay = get_timer(0) + max(100, (int)pgood_delay);
• /*

• * Record the power-on timeout here. The max. delay (timeout)
  

• * will be done based on this value in the USB port loop in
  

• * usb_hub_configure() later.
  

• */
  

• dev->connect_timeout = get_timer(0) + pgood_delay + 1000;

I'd be tempted to make that:

dev->connect_timeout = dev->query_delay + 1000;

That way, if the max() used in the calculation of dev->query_delay was dominated by the 100 not the pgood_delay, then we still get a 1000ms time for the device to connect after the power is stable. Currently, if pgood_delay<=100 (is that legal?) then the delta might be as little as 900ms (for pgood_delay==0).

static LIST_HEAD(usb_scan_list);

You could put that onto the stack in usb_hub_configure() and pass it as a parameter to usb_device_list_scan(). That would avoid some globals, which might make it easier to apply this technique across multiple controllers/hubs/... in the future?

+static int usb_scan_port(struct usb_device_scan *usb_scan)

• ret = usb_get_port_status(dev, i + 1, portsts);
• if (ret < 0) {

• debug("get_port_status failed\n");
  

• return 0;
  

Shouldn't this cause a timeout eventually if it repeats forever?

• /* Test if the connection came up, and if so, exit. */
• if (portstatus & USB_PORT_STAT_CONNECTION) {

If you invert that test, you can return early and remove and indentation level from the rest of the function.

• debug("devnum=%d port=%d: USB dev found\n", dev->devnum, i + 1);
  

• /* Remove this device from scanning list */
  

• list_del(&usb_scan->list);
  

• /* A new USB device is ready at this point */
  

• debug("Port %d Status %X Change %X\n",
  

•       i + 1, portstatus, portchange);
  

It might be nice to print this a little earlier (outside the USB_PORT_STAT_CONNECTION if block) so that any USB_PORT_STAT_C_CONNECTION triggers the print, not just if C_CONNECTION && CONNECTION. That might help debug, and match the existing code.

• if (portchange & USB_PORT_STAT_C_CONNECTION) {
  

• 	debug("port %d connection change\n", i + 1);
  

• 	usb_hub_port_connect_change(dev, i);
  

• }
  

That test is always true, or the function would have returned earlier.

+static int usb_device_list_scan(void)

...

• static int running;
• int ret = 0;
• /* Only run this loop once for each controller */
• if (running)

• return 0;
  

• running = 1;

...

+out:

• /*

• * This USB controller has has finished scanning all its connected
  

• * USB devices. Set "running" back to 0, so that other USB controllers
  

• * will scan their devices too.
  

• */
  

• running = 0;

Doesn't this function only get called a single time from usb_hub_configure()? If so, I don't think the "running" variable is required.

static int usb_hub_configure(struct usb_device *dev)

• for (i = 0; i < dev->maxchild; i++) {

• struct usb_device_scan *usb_scan;
  
  

• usb_scan = calloc(1, sizeof(*usb_scan));
  

• if (!usb_scan) {
  

• 	printf("Can't allocate memory for USB device!\n");
  

• 	return -ENOMEM;
  

I think there should be some resource cleanup for the previously allocated list entries here. Perhaps that's what you meant in your other email where you talked about some missing free()s?

Hi Stephan,

On 14.03.2016 18:31, Stephen Warren wrote:

On 03/14/2016 04:18 AM, Stefan Roese wrote:

...

This patch changes the USB port scanning procedure and timeout handling in the following ways:

A few nits/typos in the description, and some review comments below.

Thanks, will update the commit text in v4.

<snip>

...

diff --git a/common/usb_hub.c b/common/usb_hub.c

...

@@ -120,7 +121,21 @@ static void usb_hub_power_on(struct usb_hub_device *hub) pgood_delay = max(pgood_delay, (unsigned)simple_strtol(env, NULL, 0)); debug("pgood_delay=%dms\n", pgood_delay);

• mdelay(pgood_delay + 1000);

• /*

• * Do a minimum delay of the larger value of 100ms or pgood_delay
  

• * so that the power can stablize before the devices are queried
  

• */
  

• dev->query_delay = get_timer(0) + max(100, (int)pgood_delay);
• /*

• * Record the power-on timeout here. The max. delay (timeout)
  

• * will be done based on this value in the USB port loop in
  

• * usb_hub_configure() later.
  

• */
  

• dev->connect_timeout = get_timer(0) + pgood_delay + 1000;

I'd be tempted to make that:

dev->connect_timeout = dev->query_delay + 1000;

That way, if the max() used in the calculation of dev->query_delay was dominated by the 100 not the pgood_delay, then we still get a 1000ms time for the device to connect after the power is stable. Currently, if pgood_delay<=100 (is that legal?) then the delta might be as little as 900ms (for pgood_delay==0).

Fixed.

...

static LIST_HEAD(usb_scan_list);

You could put that onto the stack in usb_hub_configure() and pass it as a parameter to usb_device_list_scan(). That would avoid some globals, which might make it easier to apply this technique across multiple controllers/hubs/... in the future?

Multiple controllers/hubs should be supported currently (at least in my tests). Its the parallel scanning of those controllers which might be problematic. usb_hub.c needs some general rework, as it has some more globals:

/* TODO(sjg@chromium.org): Remove this when CONFIG_DM_USB is defined */ static struct usb_hub_device hub_dev[USB_MAX_HUB]; static int usb_hub_index;

I've moved "usb_scan_list" to these declarations for now, so that all of them can be cleaned up once somebody works on task.

...

+static int usb_scan_port(struct usb_device_scan *usb_scan)

...

• ret = usb_get_port_status(dev, i + 1, portsts);
• if (ret < 0) {

•    debug("get_port_status failed\n");
  

•    return 0;
  

Shouldn't this cause a timeout eventually if it repeats forever?

Okay. I've added a timeout check here to remove such a non-functional device.

...

• /* Test if the connection came up, and if so, exit. */
• if (portstatus & USB_PORT_STAT_CONNECTION) {

If you invert that test, you can return early and remove and indentation level from the rest of the function.

Good catch. Changed in v4.

...

•    debug("devnum=%d port=%d: USB dev found\n", dev->devnum, i + 1);
  

•    /* Remove this device from scanning list */
  

•    list_del(&usb_scan->list);
  

•    /* A new USB device is ready at this point */
  

•    debug("Port %d Status %X Change %X\n",
  

•          i + 1, portstatus, portchange);
  

It might be nice to print this a little earlier (outside the USB_PORT_STAT_CONNECTION if block) so that any USB_PORT_STAT_C_CONNECTION triggers the print, not just if C_CONNECTION && CONNECTION. That might help debug, and match the existing code.

Changed in v4.

...

•    if (portchange & USB_PORT_STAT_C_CONNECTION) {
  

•        debug("port %d connection change\n", i + 1);
  

•        usb_hub_port_connect_change(dev, i);
  

•    }
  

That test is always true, or the function would have returned earlier.

Changed in v4.

...

+static int usb_device_list_scan(void)

...

...

• static int running;
• int ret = 0;
• /* Only run this loop once for each controller */
• if (running)

•    return 0;
  

• running = 1;

...

...

+out:

• /*

• * This USB controller has has finished scanning all its connected
  

• * USB devices. Set "running" back to 0, so that other USB 
  

controllers

• * will scan their devices too.
  

• */
  

• running = 0;

Doesn't this function only get called a single time from usb_hub_configure()? If so, I don't think the "running" variable is required.

Its called recursively, if hubs are stacked. So its called e.g. 5 times in this setup:

=> usb tree USB device tree: 1 Hub (480 Mb/s, 0mA) | u-boot EHCI Host Controller | +-2 Hub (480 Mb/s, 0mA) | +-3 Hub (480 Mb/s, 100mA) | | | +-7 Hub (12 Mb/s, 100mA) | +-4 Hub (480 Mb/s, 0mA) | | | +-8 Mass Storage (480 Mb/s, 200mA) | | Kingston DataTraveler 2.0 50E549C688C4BE7189942766 | | | +-9 Mass Storage (480 Mb/s, 98mA) | USBest Technology USB Mass Storage Device 09092207fbf0c4 | +-5 Mass Storage (480 Mb/s, 200mA) | 6989 Intenso Alu Line EE706F5E | +-6 Mass Storage (480 Mb/s, 200mA) JetFlash Mass Storage Device 3281440601

...

static int usb_hub_configure(struct usb_device *dev)

...

• for (i = 0; i < dev->maxchild; i++) {

•    struct usb_device_scan *usb_scan;
  
  

•    usb_scan = calloc(1, sizeof(*usb_scan));
  

•    if (!usb_scan) {
  

•        printf("Can't allocate memory for USB device!\n");
  

•        return -ENOMEM;
  

I think there should be some resource cleanup for the previously allocated list entries here. Perhaps that's what you meant in your other email where you talked about some missing free()s?

Correct. I already noticed that the malloc is missing the free part. Its added in v4.

Thanks for the review, Stefan