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Commit a805519c authored by Mike Lockwood's avatar Mike Lockwood
Browse files

libusbhost: Add callback to usb_host_run to notify when initial device discovery is done 



This can be used to eliminate race conditions in clients that operate immediately
on the currently connected device list.

Signed-off-by: default avatarMike Lockwood <lockwood@android.com>

Change-Id: I14954b9fcc84239950ead6bdc1a0a888882c2226
parent d5c4d2ae

include/usbhost/usbhost.h

+8 −0
Original line number Diff line number Diff line
@@ -42,6 +42,11 @@ typedef int (* usb_device_added_cb)(const char *dev_name, void *client_data); 
 */

typedef int (* usb_device_removed_cb)(const char *dev_name, void *client_data);



/* Callback indicating that initial device discovery is done.

 * Return true to exit from usb_host_run.

 */

typedef int (* usb_discovery_done_cb)(void *client_data);



/* Call this to initialize the USB host library. */

struct usb_host_context *usb_host_init(void);
@@ -54,10 +59,13 @@ void usb_host_cleanup(struct usb_host_context *context); 
 * added_cb will be called immediately for each existing USB device,

 * and subsequently each time a new device is added.

 * removed_cb is called when USB devices are removed from the bus.

 * discovery_done_cb is called after the initial discovery of already

 * connected devices is complete.

 */

void usb_host_run(struct usb_host_context *context,

                  usb_device_added_cb added_cb,

                  usb_device_removed_cb removed_cb,

                  usb_discovery_done_cb discovery_done_cb,

                  void *client_data);



/* Creates a usb_device object for a USB device */

libusbhost/usbhost.c

+3 −0
Original line number Diff line number Diff line
@@ -144,6 +144,7 @@ void usb_host_cleanup(struct usb_host_context *context) 
void usb_host_run(struct usb_host_context *context,

                  usb_device_added_cb added_cb,

                  usb_device_removed_cb removed_cb,

                  usb_discovery_done_cb discovery_done_cb,

                  void *client_data)

{

    struct inotify_event* event;
@@ -174,6 +175,8 @@ void usb_host_run(struct usb_host_context *context, 


    /* check for existing devices first, after we have inotify set up */

    done = find_existing_devices(added_cb, removed_cb, client_data);

    if (discovery_done_cb)

        done |= discovery_done_cb(client_data);



    while (!done) {

        ret = read(context->fd, event_buf, sizeof(event_buf));