Translation Faults on OMAP ISP update

Quoted 23 lines · Lane Brooks

On 12/02/2010 07:35 AM, Laurent Pinchart wrote:
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Any ideas on the problem? Is there a way to force a reset to the CCDC so that it will become IDLE?

Would you expect the ISP to recover gracefully if you removed the OMAP3530 or the RAM from the board and plugged it back ? The same applies to the sensor :-)

Long story short, once started, the CCDC can't be stopped before the end of the image. When you unplug the sensor the CCDC will wait forever for the end of frame. When restarted it will resume working to the previous, no longer mapped buffer, leading to IOMMU faults. The CCDC, like most ISP blocks, can't be reset individually. You need to reset the whole ISP to recover from this (blame whoever decided that individual block resets were not useful). This was done before on streamoff, but now that the ISP driver supports running multiple pipelines in parallel we can't do it anymore.

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It might be possible to write a clean patch to reset the ISP when all streams are stopped. In the meantime you can rmmod/modprobe the driver.

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Laurent,

Thanks for the feedback. The behavior makes perfect sense now. I can take it from here. Given the user *can* unplug the sensor module in our hardware, I need to do something, as locking up the kernel is not acceptable. I will first look to see if an ISP reset on stream off works, as we can sacrifice multiple pipeline support (for now).

Laurent,

Just a question on this:

Do we ever plan to support dynamic v4l2_subdevs
registration/unregistration?

I guess we'll require to "notify" the media controller device, so we add it, (or remove it) from the pipeline, and refresh the links.

I think that is going to become an important requirement, as like Lane is doing (unloading a module).

It's very likely that we can interchange camera modules, like in the Beagleboard xM, and we don't have a real reason to really not support that.

It would be very cool to be able to:

1. Plug Aptina 5MP camera sensor.
2. Load the kernel module
3. Use the camera
4. Unload the kernel module
5. Interchange the camera board for a VGA sensor
6. Load the appropriate sensor driver.

All that without needing to restart the board.

Does that really sound _that_ crazy to everyone? :)