[Qemu-devel] bt-hci-csr problem

[Qemu-devel] bt-hci-csr problem

[Dmitry Baryshkov]

Hi,

When trying to add support for bt-hci-csr to tosa I stumbled upon a
problem. hciattach always displayed "timed out" error. After short
debugging I narrowed it to the following problem:

The first packet that hciattach was sending is:
0x01, 0x00, 0xfc, 0x17,
0xc2, 0x00, 0x00, 0x09,
0x00, 0x00, 0x00, 0x19,
0x28, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00,

At first glance it's perfectly valid. However csrhci_data_len() function
adds 1 to the length of this packet and thus does not detect the end of
the packet correctly.

Most probably we should be more precise in selecting which commands have
incorrect length, shouldn't we? Or is that a problem with my hciattach?

-- 
With best wishes
Dmitry

[Qemu-devel] Re: bt-hci-csr problem

[andrzej zaborowski]

Hi,

2008/11/11 Dmitry Baryshkov <dbaryshkov@gmail.com>:
> When trying to add support for bt-hci-csr to tosa I stumbled upon a
> problem. hciattach always displayed "timed out" error. After short
> debugging I narrowed it to the following problem:
>
> The first packet that hciattach was sending is:
> 0x01, 0x00, 0xfc, 0x17,
> 0xc2, 0x00, 0x00, 0x09,
> 0x00, 0x00, 0x00, 0x19,
> 0x28, 0x00, 0x00, 0x00,
> 0x00, 0x00, 0x00, 0x00,
> 0x00, 0x00, 0x00, 0x00,
> 0x00, 0x00, 0x00,
>
> At first glance it's perfectly valid. However csrhci_data_len() function
> adds 1 to the length of this packet and thus does not detect the end of
> the packet correctly.
>
> Most probably we should be more precise in selecting which commands have
> incorrect length, shouldn't we? Or is that a problem with my hciattach?

I suppose probably your device has a standard serial HCI?  The
bt-hci-csr is some Broadcom CSR chip which is not standard because it
aligns frame sizes to multiples of 2, so it uses a non-standard driver
in the n800 linux.

As far as I'm concerned the only differences are this frame size
alignment and the presence of vendor specific commands for firmware
upload.  If you remove these two things you should get a standard
serial dongle (if I can suggest a name, I'd call it bt-hci-uart.c).

Cheers