2009-09-02 01:05:01     v4l driver for ov9655 sensor on bf527 EZkit

2009-09-02 01:05:01     v4l driver for ov9655 sensor on bf527 EZkit

r sultana (INDIA)

Message: 79466   

Hi all,

I need help regarding ov9655 sensor support on Blackfin527 EZkit. I am trying to validate the existing V4L driver in the latest 2009 release. I need to know whether i can use the same driver without any modifications to test the sensor. I am trying to capture an UYVY format SXGA image using a test application. Can anyone help me in this regard.

Has anyone worked on the same configuration as specified above and found it working as it is?

Thanks,

rsultana170.

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2009-09-02 01:56:05     Re: v4l driver for ov9655 sensor on bf527 EZkit

Mike Frysinger (UNITED STATES)

Message: 79471   

we've never validated the ov9655 sensor.  some one else contributed the driver.

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2009-09-02 02:08:01     Re: v4l driver for ov9655 sensor on bf527 EZkit

r sultana (INDIA)

Message: 79474   

Hi Mike,

Thanks for the immediate reply.

While going through the v4l driver file blackfin_cam.c, I came across the code which is related to top_buffer and bottom buffer concept.  Can you help me in understanding what is the significance of it w.r.t to buffer allocation in the driver space.  The SDRAM starts from 0x00000 and ends at 0x3FFFF in my case.

CONFIG_BOOT_LOAD is 0x1000;

/* drivers/media/video/blackfin/blackfin_cam.c */

      bottom_buffer = (unsigned char *)0x1000;

#if !defined(USE_2ND_BUF_IN_CACHED_MEM)

        top_buffer =

            dma_alloc_coherent(NULL, MAX_BUFFER_SIZE, &dma_handle, GFP_KERNEL);

#else

        top_buffer = kmalloc(MAX_BUFFER_SIZE, GFP_KERNEL);

#endif

        if (NULL == top_buffer) {

                printk(KERN_ERR ": couldn't allocate dma buffer.\n");

                return -ENOMEM;

        }

        printk(" TOP BUFFER ALLOCATED \n");

  if ((bottom_buffer == (unsigned char *)0x1000) &&

            ((bottom_buffer + MAX_BUFFER_SIZE) <=

             (unsigned char *)CONFIG_BOOT_LOAD)) {

                printk(KERN_ERR ": couldn't allocate bottom buffer -"

                       " kernel start address too low\n");

It would be great if you can help me in this regard.

Thanks

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2009-09-02 03:09:53     Re: v4l driver for ov9655 sensor on bf527 EZkit

Mike Frysinger (UNITED STATES)

Message: 79477   

it is a hack to try and get two buffers in different pages of memory.  one at the bottom of memory and one at the top.  set your boot load address too low and the driver probably wont work.