Hi Daniel,
On Thursday 26 May 2011 15:06:17 Daniel Lundborg wrote:
> > On Thursday 26 May 2011 10:57:39 Daniel Lundborg wrote:
> > > Hello,
> > >
> > > I am developing a camera sensor driver for the Aptina MT9V034. I am only
> > > using it in snapshot mode and I can successfully trigger the sensor and
> > > receive pictures using the latest omap3isp driver from
> > > git://linuxtv.org/pinchartl/media.git branch omap3isp-next-sensors with
> > > kernel 2.6.38.
> > >
> > > I configure the sensor with media-ctl:
> > >
> > > media-ctl -r -l '"mt9v034 3-0048":0->"OMAP3 ISP CCDC":0[1], "OMAP3 ISP
> > > CCDC":1->"OMAP3 ISP CCDC output":0[1]'
> > >
> > > media-ctl -f '"mt9v034 3-0048":0[SGRBG10 752x480], "OMAP3 ISP
> > > CCDC":1[SGRBG10 752x480]'
> > >
> > > And take pictures with yavta:
> > >
> > > ./yavta -f SGRBG10 -s 752x480 -n 6 --capture=6 -F /dev/video2
> > >
> > > My trouble is that I am always receiving whiter pictures when I wait a
> > > moment before triggering the sensor to take a picture. If I take several
> > > pictures in a row with for instance 20 ms between them, they all look
> > > ok. But if I wait for 100 ms the picture will get much whiter.
> > >
> > > I have turned off auto exposure and auto gain in the sensor and the
> > > LED_OUT signal always have the same length (in this case 8 msec).
> >
> > I assume you've measured it with a scope ?
> >
> > Try disabling black level calibration and row noise correction as well.
> > Please also double-check that AEC and AGC are disabled. I've had a similar
> > issue with an MT9V032 sensor, where a bug in the driver enabled AEC/AGC
> > instead of disabling them.
>
> The register on 0xaf (MT9V034_AGC_AEC_ENABLE) is set to 0 and is 0 when
> I read from it.
> bit 0 - AEC enable context A, bit 1 - AGC enable context A, bit 8 - AEC
> enable context B, bit 9 - AGC enable context B
>
> The register on 0x47 (MT9V034_BL_CALIB_CTRL) is set to 0 and is 0 when I
> read from it.
> bit 0 - (1 = override with programmed values, 0 = normal operation), bit
> 7:5 - Frames to average over
If I'm not mistaken "normal operation" means that automatic black level
calibration is enabled. Try to set bit 0 to 1 to override the automatic
algorithm (and program a zero value in register 0x48).
> The register on 0x70 (MT9V034_ROW_NOISE_CORR_CONTROL) is set to 0 and is
> 0 when I read from it.
> bit 0 - enable noise correction context A , bit 1 - Use black level avg
> context A, bit 8 - enable noise correction context B, bit 9 - Use black
> level avg context B
>
> I measure the signals with a scope and the LED_OUT signal is always 8
> msec when triggered.
>
> Code from my mt9v034.c:
[snip]
> And from my board-overo.c file:
>
> void overo_camera_configure(struct v4l2_subdev *subdev)
> {
> struct isp_device *isp =
> v4l2_dev_to_isp_device(subdev->v4l2_dev);
>
> isp_reg_clr_set(isp, OMAP3_ISP_IOMEM_MAIN, ISP_TCTRL_CTRL,
> ~0x9a1b63ff, 0x98036000); // Set CAM_GLOBAL_RESET pin as output, enable
> shutter, set DIVC = 216
> isp_reg_clr(isp, OMAP3_ISP_IOMEM_MAIN, ISP_TCTRL_SHUT_DELAY,
> 0x01ffffff); // Set no shutter delay
> isp_reg_clr_set(isp, OMAP3_ISP_IOMEM_MAIN, ISP_TCTRL_SHUT_LENGTH,
> 0x01ffffff, 0x000003e8); // Set shutter signal length to 1000 (=> 1000 *
> 1/216MHz * 216 = 1 ms)
> isp_reg_clr_set(isp, OMAP3_ISP_IOMEM_MAIN, ISP_TCTRL_GRESET_LENGTH,
> 0x01ffffff, 0x000003e8); // Set CAM_GLOBAL_RESET signal length to 1000
> (=> 1000 * 1/216MHz * 216 = 1 ms)
> }
>
> static void overo_camera_take_picture(struct v4l2_subdev *subdev)
> {
> struct isp_device *isp =
> v4l2_dev_to_isp_device(subdev->v4l2_dev);
>
> isp_reg_clr_set(isp, OMAP3_ISP_IOMEM_MAIN, ISP_TCTRL_CTRL, 0,
> 0x00e00000); // Enable shutter (SHUTEN bit = 1)
> isp_reg_clr_set(isp, OMAP3_ISP_IOMEM_MAIN, ISP_TCTRL_CTRL, 0,
> 0x20000000); // Start generation of CAM_GLOBAL_RESET signal (GRESETEN
> bit = 1)
> }
I'll have to implement support for that in the OMAP3 ISP driver at some point.
[snip]
> > Do you have a light source connected to the LED_OUT signal ? If so, can
> > you try disabling it and using a constant light source ?
>
> No I'm not using the LED_OUT signal other than measuring the exposure time
> at this point.
>
> > > Why would the pictures become whiter if I wait a moment before taking a
> > > picture?
> > >
> > > If I set the sensor in streaming mode all pictures look like they
> > > should.
> > >
> > > Could there be something with the H3A auto white balance or auto
> > > exposure?
> >
> > The OMAP3 ISP isn't able to apply any H3A algorithm to the images by
> > itself. The H3A hardware support only computes statistics, and a userspace
> > application then needs to compute parameters (such as exposure time and
> > gains) based on the statistics, and apply them to the hardware. As yavta
> > doesn't include H3A algorithms, the differences in picture brightness can
> > only come from the sensor.
--
Regards,
Laurent Pinchart
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