On Mon, May 05, 2014 at 11:09:30AM +0200, Andrzej Pietrasiewicz wrote:
> W dniu 04.05.2014 09:48, Peter Chen pisze:
> >Hi Sebastian & Andrzej,
>
> <snip>
>
> >
> >My questions:
> >
>
> <snip>
>
> >- How to choose gserial? I tried to remove the configuration
> >of mass storage, but both of configurations have been removed
> >
> >root@freescale /sys/kernel/config/usb_gadget/g1$ rm -rf
> >configs/c.2/mass_storage
> >.1/
> >configfs-gadget gadget: unbind function 'gser'/be822b80
> >configfs-gadget gadget: unbind function 'Mass Storage Function'/be822d80
> >
>
> When you remove a symbolic link pointing at a function when the gadget is
> bound
> (active), then the gadget is unbound by design.
> There is no perfect solution to this problem. When the gadget is bound
> the host has already enumerated it and selected the gadget's configuration.
> What would it mean if gadget's identity/composition changed? As far as
> I know the USB standard does not allow changig device's identity and/or
> structure (that is: what configurations and functions there are) on the fly.
> So a sensible solution here is to force gadget's unbind so it can be
> bound again with new identity/composition.
>
> And it is not device's (gadget's) role at all to decide which configuration
> to activate. USB is a host-centric bus and nothing happens on the bus
> without host's initiative. It is totally up to the host which configuration
> to select. The host must know somehow which one to choose. Please be aware
> that some proprietary operating systems never ask for configurations
> other than the one at index 0.
>
> You can have more than one function (interface from the host's point of view)
> in one configuration and the host should handle it properly. The host must
> know how to do it, though, so you need appropriate host-side drivers and/or
> their
> parameters set properly.
>
Thanks Andrzej & Peter. (Mailbox problem, this email should be out
yesterday)
1. I have setup successfully for running mass storage and CDC ACM at the
same time with below steps:
- Using CDC ACM config (CONFIG_USB_CONFIGFS_ACM), I thought the gser at
configfs is the same with g_serial, but in fact, it is not. The gser at
configfs seems to work not well at my linux pc, it can't create serial
port, but the acm and g_serial can let the pc create /dev/ttyACM0.
- Create two interfaces at one configurations mkdir
functions/mass_storage.1 echo "/dev/mmcblk0p1" >
functions/mass_storage.1/lun.0/file
ln -s functions/mass_storage.1 configs/c.1 mkdir functions/acm.1 ln -s
functions/acm.1 configs/c.1
- Let udc run
echo ci_hdrc.0 > UDC
At host, I can see both interfaces at one configuration.
2. But when I try to remove one function, it removes two functions
together, does it be expected? Andrzej has answered, it is expected.
root@freescale /sys/kernel/config/usb_gadget/g1$ rm -rf
configs/c.1/mass_storage .1/ configfs-gadget gadget: unbind function
'acm'/be443e40 configfs-gadget gadget: unbind function 'Mass Storage
Function'/be595280 root@freescale /sys/kernel/config/usb_gadget/g1$ ls
-l configs/c.1/
-rw-r--r-- 1 root root 4096 Apr 30 00:37 MaxPower
lrwxrwxrwx 1 root root 0 Apr 30 00:39 acm.1 ->
../../../../usb_gadget/g1/functions/acm.1
-rw-r--r-- 1 root root 4096 Apr 30 01:02 bmAttributes
drwxr-xr-x 2 root root 0 Apr 30 00:37 strings
3. Besides, I have tried two configurations, and each configuration with
one function, I find the host PC always set configuration 1 (The first
configuration), any ways to switch configuration at host
side? libusb?
When I tried to delete one un-selected configuration (configuration 2),
the configfs also delete both functions two. Andrzej has answered,
it is expected.
root@freescale /sys/kernel/config/usb_gadget/g1$ rm -rf
configs/c.2/mass_storage .1/ configfs-gadget gadget: unbind
function 'acm'/beb85180 configfs-gadget gadget: unbind function
'Mass Storage Function'/be524f80
--
Best Regards,
Peter Chen
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