[linux-dvb] [PATCH] Support faulty USB IDs on DIBUSB_MC

Devin Heitmueller devin.heitmueller at gmail.com
Mon Feb 9 20:44:54 CET 2009


On Mon, Feb 9, 2009 at 2:40 PM, matthieu castet <castet.matthieu at free.fr> wrote:
> Hi,
>
> matthieu castet wrote:
>>
>> 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.
>>
> Patrick, any info about that.
>
> I attach a possible (untested) patch.
>
>
> Matthieu
>
> Signed-off-by: Matthieu CASTET <castet.matthieu at free.fr>
> Index: linux-2.6/drivers/media/dvb/dvb-usb/dibusb-common.c
> ===================================================================
> --- linux-2.6.orig/drivers/media/dvb/dvb-usb/dibusb-common.c    2009-02-09
> 20:36:03.000000000 +0100
> +++ linux-2.6/drivers/media/dvb/dvb-usb/dibusb-common.c 2009-02-09
> 20:38:21.000000000 +0100
> @@ -133,14 +133,18 @@
>
>        for (i = 0; i < num; i++) {
>                /* write/read request */
> -               if (i+1 < num && (msg[i+1].flags & I2C_M_RD)) {
> +               if (i+1 < num && (msg[i].flags & I2C_M_RD) == 0
> +                                         && (msg[i+1].flags & I2C_M_RD)) {
>                        if (dibusb_i2c_msg(d, msg[i].addr,
> msg[i].buf,msg[i].len,
>                                                msg[i+1].buf,msg[i+1].len) <
> 0)
>                                break;
>                        i++;
> -               } else
> +               } else if ((msg[i].flags & I2C_M_RD) == 0) {
>                        if (dibusb_i2c_msg(d, msg[i].addr,
> msg[i].buf,msg[i].len,NULL,0) < 0)
>                                break;
> +               }
> +               else
> +                       break;
>        }
>
>        mutex_unlock(&d->i2c_mutex);

The assumption that you can only have write/read or write requests is
one of the big things fixed in the 1.20 firmware.  If you are running
the 1.20 firmware, you just need to add the option to use the new i2c
function instead of the legacy i2c transfer function.

Devin

-- 
Devin J. Heitmueller
http://www.devinheitmueller.com
AIM: devinheitmueller



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