Re: [RFC PATCH v5 13/14] media: tegra-video: Add CSI MIPI pads calibration

[Sowjanya Komatineni]

On 7/29/20 4:59 PM, Sowjanya Komatineni wrote:
> On 7/29/20 4:25 PM, Dmitry Osipenko wrote:
> > 28.07.2020 18:59, Sowjanya Komatineni ÐÐÑÐÑ:
> > ...
> > > > > +ÂÂÂÂÂÂÂ ret = tegra_mipi_finish_calibration(csi_chan->mipi);
> > > > > +ÂÂÂÂÂÂÂ if (ret < 0)
> > > > > +ÂÂÂÂÂÂÂÂÂÂÂ dev_err(csi_chan->csi->dev,
> > > > > +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ "MIPI calibration failed: %d\n", ret);
> > > > Doesn't v4l2_subdev_call(OFF) need to be invoked here on error?
> > > Not required as on error streaming fails and runtime PM will turn off
> > > power anyway.
> > I see that camera drivers bump theirs RPM on s_stream=1, and thus,
> > s_stream=0 should be invoked in order to balance the RPM. What am I 
> > missing?
> >
> > https://elixir.bootlin.com/linux/v5.8-rc4/source/drivers/media/i2c/ov2740.c#L634 
>
> Sensor drivers take care of RPM put when any failure happens during 
> s_stream.
>
> So bridge driver don't have to call v4l2_subdev_call s_stream off 
> incase if sensor subdev stream on fails.
>
> > > Also we only did csi subdev s_stream on and during sensor subdev
> > > s_stream on fail, actual stream dont happen and on tegra side frame
> > > capture by HW happens only when kthreads run.
> > Secondly, perhaps a failed calibration isn't a very critical error?
> > Hence just printing a warning message should be enough.
>
> Using dev_err to report calibration failure. Are you suggesting to use 
> dev_warn instead of dev_err?
>
> > Could you please make a patch that factors all ON/OFF code paths into a
> > separate functions? It's a bit difficult to follow the combined code,
> > especially partial changes in the patches. Thanks in advance!
>
> what do you mean by partial changes in patches?
>
> Can you please be more clear?

Also please specify what ON/OFF code paths you are referring to when you 
say to move into separate functions?

> Thanks
>
> Sowjanya