[meta-ti] [PATCH meta-ti] linux-ti33x-psp 3.1rc8: Enable usb-to-serial drivers

[Fernandes, Joel A]

Hi Jason,

> Can you also enable other types of USB host adapters?  We want to have
> a fairly exhaustive set, including just about every USB-to-serial
> adapter.

Actually considering that the actual UART is connected to the FTDI and provided from the device
port, do we still want to do this? For the case of the bone tester board, we're controlling
the hardware so we have a specific usb-serial device we'd like to have enabled in the kernel.
For customers running tests after the board ships, they can always run the individual tests
and see the output on the FTDI serial port. For a regular serial console, they already have one
so they don't need a usb-serial device, in the case of the tester we had to do this because we
run out of ports due to the loopback.

> I had been thinking that Koen has some mechanism where USB drivers are
> registered after boot based on this set of messages in the kernel
> bootlog:
> [    0.254977] usbcore: registered new interface driver catc
> [    0.254991] catc: v2.8:CATC EL1210A NetMate USB Ethernet driver
> [    0.255057] usbcore: registered new interface driver kaweth
> [    0.255074] pegasus: v0.6.14 (2006/09/27), Pegasus/Pegasus II USB
> Ethernet driver
> [    0.255142] usbcore: registered new interface driver pegasus
> [    0.255157] rtl8150: v0.6.2 (2004/08/27):rtl8150 based usb-ethernet
> driver

I think the mechanism is the init functions of the drivers register themselves with the USB
Subsystem when the kernel boots. Also the messages above occur before root filesystem mounts so
don't think Koen is doing anything there.

> [    0.255233] usbcore: registered new interface driver rtl8150
> [    0.255299] usbcore: registered new interface driver asix
> [    0.255366] usbcore: registered new interface driver cdc_ether
> [    0.255433] usbcore: registered new interface driver dm9601
> [    0.255500] usbcore: registered new interface driver cdc_subset
> [    0.255566] usbcore: registered new interface driver zaurus
> [    0.255623] cdc_ncm: 04-Aug-2011
> [    0.255693] usbcore: registered new interface driver cdc_ncm
> [    0.255817] usbcore: registered new interface driver cdc_acm
> [    0.255831] cdc_acm: USB Abstract Control Model driver for USB
> modems and ISDN adapters
> [    0.255927] usbcore: registered new interface driver usblp
> [    0.255997] usbcore: registered new interface driver cdc_wdm
> 
> However, looking at the defconfig, it seems these are just set as Y,
> the same as you have done.  Just wondering if you had any clarity to
> add to that with ideas on how we can make the kernel smaller for a fast
> boot while still handling more devices.  I hate for people to have to
> reconfigure the kernel just because we didn't compile something useful
> into it.

We could build them as modules, but I don't think we should include any more
usb-to-serial drivers even as modules as the onboard FTDI is already providing this.

Koen has provided a pretty exhaustive defconfig as we know :)

Thanks,
Joel