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Commit f4de0783 authored by Benoit Goby's avatar Benoit Goby
Browse files

libusbhost: Fix USB device discovery on boot 

On some devices, /dev/bus/usb does not exist on boot, it is only created
when the otg port is in host mode. Use inotify to detect when /dev/bus/usb
is created and then start watching subdirectories.

Change-Id: Ic1472a5ea7a7118cdbb560cc7071ade9bcee753a
parent 6cc883ca

libusbhost/usbhost.c

+43 −15
Original line number Diff line number Diff line
@@ -49,6 +49,7 @@ 


#include "usbhost/usbhost.h"



#define DEV_DIR             "/dev"

#define USB_FS_DIR          "/dev/bus/usb"

#define USB_FS_ID_SCANNER   "/dev/bus/usb/%d/%d"

#define USB_FS_ID_FORMAT    "/dev/bus/usb/%03d/%03d"
@@ -110,7 +111,7 @@ static int find_existing_devices(usb_device_added_cb added_cb, 
    int done = 0;



    busdir = opendir(USB_FS_DIR);

    if(busdir == 0) return 1;

    if(busdir == 0) return 0;



    while ((de = readdir(busdir)) != 0 && !done) {

        if(badname(de->d_name)) continue;
@@ -124,6 +125,25 @@ static int find_existing_devices(usb_device_added_cb added_cb, 
    return done;

}



static void watch_existing_subdirs(struct usb_host_context *context,

                                   int *wds, int wd_count)

{

    char path[100];

    int i, ret;



    wds[0] = inotify_add_watch(context->fd, USB_FS_DIR, IN_CREATE | IN_DELETE);

    if (wds[0] < 0)

        return;



    /* watch existing subdirectories of USB_FS_DIR */

    for (i = 1; i < wd_count; i++) {

        snprintf(path, sizeof(path), "%s/%03d", USB_FS_DIR, i);

        ret = inotify_add_watch(context->fd, path, IN_CREATE | IN_DELETE);

        if (ret >= 0)

            wds[i] = ret;

    }

}



struct usb_host_context *usb_host_init()

{

    struct usb_host_context *context = calloc(1, sizeof(struct usb_host_context));
@@ -156,29 +176,25 @@ void usb_host_run(struct usb_host_context *context, 
    char event_buf[512];

    char path[100];

    int i, ret, done = 0;

    int wd, wds[10];

    int wd, wdd, wds[10];

    int wd_count = sizeof(wds) / sizeof(wds[0]);



    D("Created device discovery thread\n");



    /* watch for files added and deleted within USB_FS_DIR */

    memset(wds, 0, sizeof(wds));

    for (i = 0; i < wd_count; i++)

        wds[i] = -1;



    /* watch the root for new subdirectories */

    wds[0] = inotify_add_watch(context->fd, USB_FS_DIR, IN_CREATE | IN_DELETE);

    if (wds[0] < 0) {

    wdd = inotify_add_watch(context->fd, DEV_DIR, IN_CREATE | IN_DELETE);

    if (wdd < 0) {

        fprintf(stderr, "inotify_add_watch failed\n");

        if (discovery_done_cb)

            discovery_done_cb(client_data);

        return;

    }



    /* watch existing subdirectories of USB_FS_DIR */

    for (i = 1; i < wd_count; i++) {

        snprintf(path, sizeof(path), "%s/%03d", USB_FS_DIR, i);

        ret = inotify_add_watch(context->fd, path, IN_CREATE | IN_DELETE);

        if (ret > 0)

            wds[i] = ret;

    }

    watch_existing_subdirs(context, wds, wd_count);



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

    done = find_existing_devices(added_cb, client_data);
@@ -190,7 +206,19 @@ void usb_host_run(struct usb_host_context *context, 
        if (ret >= (int)sizeof(struct inotify_event)) {

            event = (struct inotify_event *)event_buf;

            wd = event->wd;

            if (wd == wds[0]) {

            if (wd == wdd) {

                if ((event->mask & IN_CREATE) && !strcmp(event->name, "bus")) {

                    watch_existing_subdirs(context, wds, wd_count);

                    done = find_existing_devices(added_cb, client_data);

                } else if ((event->mask & IN_DELETE) && !strcmp(event->name, "bus")) {

                    for (i = 0; i < wd_count; i++) {

                        if (wds[i] >= 0) {

                            inotify_rm_watch(context->fd, wds[i]);

                            wds[i] = -1;

                        }

                    }

                }

            } else if (wd == wds[0]) {

                i = atoi(event->name);

                snprintf(path, sizeof(path), "%s/%s", USB_FS_DIR, event->name);

                D("%s subdirectory %s: index: %d\n", (event->mask & IN_CREATE) ?
@@ -199,7 +227,7 @@ void usb_host_run(struct usb_host_context *context, 
                    if (event->mask & IN_CREATE) {

                        ret = inotify_add_watch(context->fd, path,

                                                IN_CREATE | IN_DELETE);

                        if (ret > 0)

                        if (ret >= 0)

                            wds[i] = ret;

                        done = find_existing_devices_bus(path, added_cb,

                                                         client_data);