Re: [PATCH] Support faulty USB IDs on DIBUSB_MC

[matthieu castet <castet.matthieu@free.fr>]

matthieu castet wrote:
> Hi Patrick,
> 
> Patrick Boettcher wrote:
>> Hi,
>>
>> sorry for not answering ealier, recently I became the master of 
>> postponing things. :(
>>
>> On Thu, 29 Jan 2009, Mauro Carvalho Chehab wrote:
>>
>>>> +/* 14 */    { USB_DEVICE(USB_VID_CYPRESS,        
>>>> USB_PID_ULTIMA_TVBOX_USB2_FX_COLD) },
>>>> +#endif
>>>
>>> It doesn't sound a very good approach the need of recompiling the 
>>> driver to
>>> allow it to work with a broken card. The better would be to have some 
>>> modprobe
>>> option to force it to accept a certain USB ID as a valid ID for the 
>>> card.
>>
>> The most correct way would be to reprogram the eeprom, by simply 
>> writing to 0xa0 (0x50 << 1) I2C address... There was a thread on the 
>> linux-dvb some time ago.
>>
BTW dibusb_i2c_xfer seems to do things very dangerous :
it assumes that it get only write/read request or write request.

That means that read can be understood as write. For example a program 
doing
file = open("/dev/i2c-x", O_RDWR);
ioctl(file, I2C_SLAVE, 0x50)
  read(file, data, 10)
will corrupt the eeprom as it will be understood as a write.

Now that I think of that, I run sensors-detect on this machine, may be 
this is what trash the eeprom ?


Matthieu