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Re: [Spca50x-devs] Questions about implementing PAC7311 driver




Michel Xhaard wrote:
> Le Samedi 3 Mars 2007 07:27, Denver Gingerich a écrit :
>> I've been working on implementing support for the PAC7311 with
>> significant help from Joerg Schummer's "Webcam Development Kit" on
>> Thomas Kaiser's page
>> (http://www.kaiser-linux.li/index.php?title=PAC7311).  It seems to be
>> working to some extent (it recognizes the camera and sets the initial
>> register values without
>> crashing), but the URBs it's sending back are all empty
>> (urb->iso_frame_desc[i].actual_length and urb->actual_length are
>> always 0).
>>
>> I compared the URBs received by the GSPCA driver and those received by
>> Joerg's development kit and here's what I've found (excuse the horrible
>> tabbing):
>>
>>                                     GSPCA     dev kit
>> transfer_flags                6             2
>> transfer_buffer_length   16368     65472
>> actual_length                 0             <variable>
>> status                            0             0
>> interval                          1             1
>> number_of_packets       16           32
>> error_count                    0             0
>>
>> The transfer_flags are URB_ISO_ASAP | URB_NO_TRANSFER_DMA_MAP (for
>> GSPCA) and URB_ISO_ASAP (for the dev kit).
>>
>> It doesn't seem like any of the above differences should have an
>> effect on whether the webcam sends packets properly (all the other
>> GSPCA cameras work fine with those settings), but perhaps I'm missing
>> something.  I've double-checked the initialization work I've done to
>> setup the correct register values and that seems to be fine (assuming
>> that the control messages aren't ordered in reverse or something
>> strange like that).
>>
>> You can check out the work I've done so far on the PAC7311 for the
>> GPSCA driver at http://ossguy.com/linux/webcam/pac7311/pac7311_v1.patch. 
>> It should apply cleanly to the 20070110 version of GSPCA.
>>
>> Any help would be appreciated.  Thanks.
>>
>> Denver
>>
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> Denver,
> Seem the chips is not initialised like in the developpement kit from Joerg and 
> Thomas, that is why you get empty buffer from the Iso stream. I did not know 
> why, maybe double check your code in init and start 
> Best regards and thanks for working on it, a lot of people are waiting for :)

Hello Michel

I did already answer Denver off list. Anyway I just started to implement 
  PAC7311 into gspcaV1 this week. I get a stream and sent my code to Denver.

I am working on the framedecoder right now and I don't know what I 
should do with this special "Pixart" MCU markers. According to Joerg, we 
have to decode the huffman code to find these markers, so I think I will 
get the "JPEG Pixart" stream to userspace and modify spcaview for 
decoding, for a first test/alpha version of PAC7311 support.

What do you think?

Thomas

-- 
http://www.kaiser-linux.li

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