Hi,
On 4 March 2015 at 07:09, Guoyin Chen <guoyin.c...@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
> 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;
> }
>
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