Hi,

I would like to explore what level of support is available in the v4l buffer 
exchange mechanism for USERPTR buffer exchange.

In our internal release, we had a hack to support this feature. We use 
contiguous buffers in our user ptr hack implementation. The buffers are 
allocated in a kernel module that export api to pass the physical address of 
the allocated buffer to the user application. In the v4l2 driver, USERPTR IO 
mechanism will be requested, and in QBUF, the ptr passed to the driver is the 
above physical address. One thing we observed was that even in this case, we 
had to use index in the buffer structure without which it doesn't work.

Anyone has any insight into how to port this capability to the open source 
kernel v4l2 driver? In other words, can I use userptr IO mechanism and pass 
contigous buffer address like above? If so, Is there a driver example I can 
refer to port this to my vpfe capture driver?  

Thanks in advance.

Murali Karicheri
Software Design Engineer
Texas Instruments Inc.
Germantown, MD 20874
email: m-kariche...@ti.com

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