Re: [PATCH 0/2] media: ov5640: drive-by frame_interval cleanups

[Jai Luthra <j-luthra@ti.com>]

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Hi Jacopo, Guoniu,

On 05/05/23 12:46, Jacopo Mondi wrote:
> While looking at Guoniu Zhou patches I noticed that there were a few cleanups
> related to the usage of frame_interval fileds for MIPI CSI-2 framerate
> calculations.
> 
> No functional changes intended, just cleanups.
> 
> Guoniu: could you please test these on your setup as well ? A tested-by tag
> would be useful!
> 

Thanks for the latest fixes!

Testing on my setup (CSI module w/ 2 lanes), I notice two weird issues 
and wonder if you see the same behavior on your setups?

Issue 1
-------

On a fresh boot the sensor streams at 60fps, and checking link_freq from 
v4l2-ctl I get 384Mhz. But G_FRAME_INTERVAL returns 30FPS when using 
`media-ctl -p`:
[stream:0 fmt:UYVY8_1X16/640x480@1/30]

Issue 2
-------

If I manually set the frame interval to @1/60 using media-ctl, and then 
stream it - actual framerate gets reduced to 30FPS:

root@am62xx-evm:~# yavta -s 640x480 -f UYVY /dev/video0 -c5
....
0 (0) [-] any 0 614400 B 401.488754 401.488855 12.719 fps ts mono/EoF
1 (1) [-] any 1 614400 B 401.522057 401.522147 30.027 fps ts mono/EoF
2 (2) [-] any 2 614400 B 401.555434 401.555584 29.961 fps ts mono/EoF
3 (3) [-] any 3 614400 B 401.588723 401.588814 30.040 fps ts mono/EoF
4 (4) [-] any 4 614400 B 401.622051 401.622135 30.005 fps ts mono/EoF
Captured 5 frames in 0.212005 seconds (23.584252 fps, 14490164.140730 B/s).
8 buffers released.

After setting frame interval to @1/60, the link-frequency got reduced to 
192Mhz, which probably explains the low framerate.

root@am62xx-evm:~# v4l2-ctl -d /dev/v4l-subdev2 -C link_frequency
link_frequency: 19 (192000000 0xb71b000)

I will take a deeper look at update_pixel_rate() function to try and fix 
this - but wanted to confirm if this also happens on your CSI sensors?

I also repeated same tests without this series and still saw both 
issues. In fact Issue 2 was worse because the sensor did not stream *at 
all* if I changed frame interval to @1/60. My guess is PATCH 2/2 fixes 
that by not updating the VBLANK using the DVP values.

For the series:

Tested-by: Jai Luthra <j-luthra@ti.com>

Thanks,
Jai

> Thanks
>    j
> 
> Jacopo Mondi (2):
>    media: ov5640: Remove unused 'framerate' parameter
>    media: ov5640: Drop dead code using frame_interval
> 
>   drivers/media/i2c/ov5640.c | 17 +----------------
>   1 file changed, 1 insertion(+), 16 deletions(-)
> 
> --
> 2.40.1
> 

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