[Letux-kernel] GTA04 camera driver

[H. Nikolaus Schaller]

> Am 16.04.2017 um 17:34 schrieb H. Nikolaus Schaller <hns at goldelico.com>:
> 
> Hi,
> I think I am a little closer to finding the issue(s)...
> 
> First of all I observed that although power is properly
> turned on (ov965x_s_power), there is no call to
> ov965x_s_stream which IMO should turn on the video
> stream. There is only a single call to ov965x_get_fmt()
> as the only other activity after ov965x_s_power()
> and before I stop mplayer (which calls ov965x_s_power()
> to turn the camera module off). In log lines:
> 
> [  620.049804] ov965x_s_power: on: on
> [  620.352020] ov965x_get_fmt(which=1)
> [  628.761810] ov965x_s_power: on: off
> 
> Therefore, I have looked into the isp code where the
> camera should be turned on. It looks like this is
> done in isp_video_streamon().
> 
> Now some prinkt in isp_video_streamon() show that it
> returns -EPIPE. Which appears as if it is not reported
> to userspace and makes mplayer show a green screen.
> 
> 
> [  620.049804] ov965x_s_power: on: on
> [  620.147277] ov965x_write: 0x01 @ 0x09 (2)
> [  620.151916] ov965x_write: 0x40 @ 0x15 (2)
> [  620.157989] ov965x_write: 0x00 @ 0x11 (2)
> [  620.162658] ov965x_write: 0x4a @ 0x6B (2)
> [  620.178619] ov965x_write: 0x40 @ 0x0F (2)
> [  620.183166] ov965x_write: 0x05 @ 0x3B (2)
> [  620.200469] ov965x_write: 0xc0 @ 0x40 (2)
> [  620.216857] ov965x_write: 0x50 @ 0x31 (2)
> [  620.222351] ov965x_write: 0x88 @ 0x3A (2)
> [  620.261779] isp_video_mmap()
> [  620.268737] isp_video_mmap()
> [  620.348297] isp_video_streamon()
> [  620.352020] ov965x_get_fmt(which=1)
> [  620.358184] isp_video_streamon() err -32
> 
> ^^^^
> vvvv ctrl-C to kill mplayer after some seconds
> 
> [  628.746398] isp_video_release()
> [  628.749755] isp_video_streamoff()
> [  628.761810] ov965x_s_power: on: off
> 
> 
> This is now a very specific symptom ready for further
> study...
> 
> Please keep fingers crossed that we can use this info
> to find out why the module isn't showing a video...

First issue is identified: the /root/camera-demo script does
not tell the camera or the camera interface to use SXGA resolution.

That becomes known to the isp driver which refuses to approve
the links/network/pipeline due to format mismatch.
Therefore we get -EPIPE.

But there is another issue I have to find which still
prevents link validation.

BR,
Nikolaus