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Subject: Re: [RFC PATCH v5 13/14] media: tegra-video: Add CSI MIPI pads
 calibration
To:     Dmitry Osipenko <digetx@gmail.com>, <thierry.reding@gmail.com>,
        <jonathanh@nvidia.com>, <frankc@nvidia.com>, <hverkuil@xs4all.nl>,
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From:   Sowjanya Komatineni <skomatineni@nvidia.com>
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Date:   Wed, 29 Jul 2020 16:59:52 -0700
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On 7/29/20 4:25 PM, Dmitry Osipenko wrote:
> 28.07.2020 18:59, Sowjanya Komatineni =D0=BF=D0=B8=D1=88=D0=B5=D1=82:
> ...
>>>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 ret =3D tegra_mipi_finish_=
calibration(csi_chan->mipi);
>>>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 if (ret < 0)
>>>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 de=
v_err(csi_chan->csi->dev,
>>>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0=C2=A0 "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=3D1, and thus,
> s_stream=3D0 should be invoked in order to balance the RPM. What am I mis=
sing?
>
> 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=20
s_stream.

So bridge driver don't have to call v4l2_subdev_call s_stream off incase=20
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=20
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?

Thanks

Sowjanya