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

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Hi Jacopo,

On May 16, 2023 at 09:46:57 +0200, Jacopo Mondi wrote:
> Hi Jai,
>    thanks for testing
> 
> On Mon, May 15, 2023 at 05:25:55PM +0530, Jai Luthra wrote:
> > 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]
> 
> the g/s_frame_interval calls are not relevant for MIPI CSI-2
> 
> I wonder if we should/could return -EINVAL in this case
> 
> 
> >
> > 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:
> 
> Ah this shouldn't happen. s_frame_interval -should not- modify the
> timings on a CSI-2 setup
> 
> If not returning -EINVAL, we should at least return immediately
> 
> >
> > 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.
> 
> Probably yes, and this confirms to me that we should return early in
> s_frame_interval if we're CSI-2 (or if this doesn't contradict the
> specification even return an error).

Oh makes sense, thanks.

I can update s_frame_interval to return -EINVAL for CSI-2 as a follow-up 
series.

Will also try if g_frame_interval can report correct framerate (60fps vs 
30fps) depending upon the bus type, as I don't think returning -EINVAL 
would be correct behavior. If that does not work maybe we can unset the 
ops hooks before registering the subdev with the framework.

> 
> Thanks
>    j
> 
> >
> > For the series:
> >
> > Tested-by: Jai Luthra <j-luthra@xxxxxx>
> >
> > 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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