adb not work in 3.14 kernel

[Guoyin Chen]

I am trying to use the branch linux-linaro-lsk-v3.14-android from Linaro or android-3.14 from AOSP. It seems the adb cannot work with f_fs.c driver.

Every time, you try the commands "mount -o uid=2000,gid=2000 -t functionfs adb /dev/usb-ffs/adb", it will failed on no device found.

in the function ffs_fs_mount(), it will try to look up a ffs_dev with the name "adb". But the android gadget driver, there is not code to register such device to f_fs.

In 3.10 kernel, the ffs_fs_mount() will worked even with a null ffs_dev returned by functionfs_acquire_dev_callback(dev_name), which defined in android.c.

Should we have some code in android gadget driver to init a adb ffs_dev as the one in g_ffs driver's gfs_init()? Or any better way to add adb ffs_dev?

3.10 kernel:

/* "mount -t functionfs dev_name /dev/function" ends up here */

static struct dentry *

ffs_fs_mount(struct file_system_type *t, int flags,

          const char *dev_name, void *opts)

{

    struct ffs_sb_fill_data data = {

        .perms = {

            .mode = S_IFREG | 0600,

            .uid = GLOBAL_ROOT_UID,

            .gid = GLOBAL_ROOT_GID,

        },

        .root_mode = S_IFDIR | 0500,

    };

    struct dentry *rv;

    int ret;

    void *ffs_dev;

    struct ffs_data *ffs;

    ENTER();

    ret = ffs_fs_parse_opts(&data, opts);

    if (unlikely(ret < 0))

        return ERR_PTR(ret);

    ffs = ffs_data_new();

    if (unlikely(!ffs))

        return ERR_PTR(-ENOMEM);

    ffs->file_perms = data.perms;

    ffs->dev_name = kstrdup(dev_name, GFP_KERNEL);

    if (unlikely(!ffs->dev_name)) {

        ffs_data_put(ffs);

        return ERR_PTR(-ENOMEM);

    }

    ffs_dev = functionfs_acquire_dev_callback(dev_name);

    if (IS_ERR(ffs_dev)) {

        ffs_data_put(ffs);

        return ERR_CAST(ffs_dev);

    }

  

    ffs->private_data = ffs_dev;

    data.ffs_data = ffs;

    rv = mount_nodev(t, flags, &data, ffs_sb_fill);

    if (IS_ERR(rv) && data.ffs_data) {

        functionfs_release_dev_callback(data.ffs_data);

        ffs_data_put(data.ffs_data);

    }

    return rv;

}

3.14 kernel:

static struct dentry *

ffs_fs_mount(struct file_system_type *t, int flags,

          const char *dev_name, void *opts)

{

    struct ffs_sb_fill_data data = {

        .perms = {

            .mode = S_IFREG | 0600,

            .uid = GLOBAL_ROOT_UID,

            .gid = GLOBAL_ROOT_GID,

        },

        .root_mode = S_IFDIR | 0500,

    };

    struct dentry *rv;

    int ret;

    void *ffs_dev;

    struct ffs_data *ffs;

    ENTER();

    ret = ffs_fs_parse_opts(&data, opts);

    if (unlikely(ret < 0))

        return ERR_PTR(ret);

    ffs = ffs_data_new();

    if (unlikely(!ffs))

        return ERR_PTR(-ENOMEM);

    ffs->file_perms = data.perms;

    ffs->dev_name = kstrdup(dev_name, GFP_KERNEL);

    if (unlikely(!ffs->dev_name)) {

        ffs_data_put(ffs);

        return ERR_PTR(-ENOMEM);

    }

    ffs_dev = ffs_acquire_dev(dev_name);

    if (IS_ERR(ffs_dev)) {

        ffs_data_put(ffs);

        return ERR_CAST(ffs_dev);

    }

    ffs->private_data = ffs_dev;

    data.ffs_data = ffs;

    rv = mount_nodev(t, flags, &data, ffs_sb_fill);

    if (IS_ERR(rv) && data.ffs_data) {

        ffs_release_dev(data.ffs_data);

        ffs_data_put(data.ffs_data);

    }

    return rv;

}

[Amit Pundir]

Hi,

On 4 March 2015 at 07:09, Guoyin Chen <guoyi...@gmail.com> wrote:
> I am trying to use the branch linux-linaro-lsk-v3.14-android from Linaro or
> android-3.14 from AOSP. It seems the adb cannot work with f_fs.c driver.
>

It's been a while but ADB over FunctionFS worked for me with
linux-linaro-lsk-v3.14-android and I don't see any reason why it
shouldn't work with android-3.14 as such.

Here are the set of instructions which worked for me:

1) Enable FunctionFS in kernel, "Device Drivers -> USB Support -> USB
Gadget Support -> USB Gadget Driver -> Function Filesystem" and boot
with this additional bootarg "g_ffs.idVendor=0x18d1".

2) Run following commands from Android shell:
$ su
# stop adbd
# mkdir /dev/usb-ffs
# mkdir /dev/usb-ffs/adb
# mount -o uid=2000,gid=2000 -t functionfs adb /dev/usb-ffs/adb
# start adbd

3) Run adb shell from host computer to verify.

The trick above is that the adb FunctionFS mount path
"/dev/usb-ffs/adb" and set of supported VendorIDs e.g
"g_ffs.idVendor=0x18d1" are hardcoded in adbd. So we can not just set
any random path/values there.

Regards,
Amit Pundir

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[Guoyin Chen]

Have you tried with the config CONFIG_USB_G_ANDROID but not CONFIG_USB_FUNCTIONFS. The android.c will include f_fs.c to support the adb over usb functionfs. Or the since 3.14, it does not support use G_ANDROID to control all android related gadget functin?