pxa_camera + ov9655: image shifted on first capture after reset

pxa_camera + ov9655: image shifted on first capture after reset

[Stefan Herbrechtsmeier]

Hi,

I have updated my ov9655 driver to kernel 2.6.33 and
did some test regarding the image shift problem on pxa.
(http://thread.gmane.org/gmane.linux.drivers.video-input-infrastructure/10773/focus=11810)

- The image was shifted 32 pixels (64 bytes) to the right
  or rather the first 32 pixels belongs to the previous image.
- The image was only shifted on the first capture after reset.
   It doesn't matter whether I previous change the resolution with v4l2-ctl.
- On big images (1280 x 1024) the shift disappears after some images,
   but not on small images (320 x 240).

It looks like the FIFO was not cleared at start capture.

Regards,
    Stefan

Re: pxa_camera + ov9655: image shifted on first capture after reset

[Jonathan Cameron]

On 04/16/10 09:25, Stefan Herbrechtsmeier wrote:
> Hi,
> 
> I have updated my ov9655 driver to kernel 2.6.33 and
> did some test regarding the image shift problem on pxa.
> (http://thread.gmane.org/gmane.linux.drivers.video-input-infrastructure/10773/focus=11810)
> 
> 
> - The image was shifted 32 pixels (64 bytes) to the right
>  or rather the first 32 pixels belongs to the previous image.
> - The image was only shifted on the first capture after reset.
>   It doesn't matter whether I previous change the resolution with v4l2-ctl.
> - On big images (1280 x 1024) the shift disappears after some images,
>   but not on small images (320 x 240).
> 
> It looks like the FIFO was not cleared at start capture.
> 
Sounds reasonable.  Similar problem seen with ov7670 attached to pxa271.
I've never taken the time to try and track it down.

Re: pxa_camera + ov9655: image shifted on first capture after reset

[Stefan Herbrechtsmeier]

Jonathan Cameron schrieb:
> On 04/16/10 09:25, Stefan Herbrechtsmeier wrote:
>   
>> Hi,
>>
>> I have updated my ov9655 driver to kernel 2.6.33 and
>> did some test regarding the image shift problem on pxa.
>> (http://thread.gmane.org/gmane.linux.drivers.video-input-infrastructure/10773/focus=11810)
>>
>>
>> - The image was shifted 32 pixels (64 bytes) to the right
>>  or rather the first 32 pixels belongs to the previous image.
>> - The image was only shifted on the first capture after reset.
>>   It doesn't matter whether I previous change the resolution with v4l2-ctl.
>> - On big images (1280 x 1024) the shift disappears after some images,
>>   but not on small images (320 x 240).
>>
>> It looks like the FIFO was not cleared at start capture
> Sounds reasonable.  Similar problem seen with ov7670 attached to pxa271.
> I've never taken the time to try and track it down.
>   
I have fix the bug by moving the reset FIFO from 
pxa_camera_start_capture to pxa_camera_irq
in front of the DMA activation after an end of frame interrupt.

I will send a patch tomorrow.

Regards,
    Stefan