linux-kernel - Re: [PATCH v1 07/19] staging: media: tegra-video: csi: parametrize MIPI calibration device presence

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Message-ID: <CAPVz0n2dp7kdCWFLWQjQY+tGO_ayzxGW=zxx3FwX_yeeR9J2Bg@mail.gmail.com>
Date: Tue, 2 Sep 2025 08:05:12 +0300
From: Svyatoslav Ryhel <clamor95@...il.com>
To: Mikko Perttunen <mperttunen@...dia.com>
Cc: Thierry Reding <thierry.reding@...il.com>, Thierry Reding <treding@...dia.com>, 
	Jonathan Hunter <jonathanh@...dia.com>, Sowjanya Komatineni <skomatineni@...dia.com>, 
	Luca Ceresoli <luca.ceresoli@...tlin.com>, David Airlie <airlied@...il.com>, 
	Simona Vetter <simona@...ll.ch>, Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
	Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Peter De Schrijver <pdeschrijver@...dia.com>, Prashant Gaikwad <pgaikwad@...dia.com>, 
	Michael Turquette <mturquette@...libre.com>, Stephen Boyd <sboyd@...nel.org>, 
	Mauro Carvalho Chehab <mchehab@...nel.org>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
	Dmitry Osipenko <digetx@...il.com>, Charan Pedumuru <charan.pedumuru@...il.com>, 
	linux-media@...r.kernel.org, linux-tegra@...r.kernel.org, 
	dri-devel@...ts.freedesktop.org, devicetree@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-clk@...r.kernel.org, 
	linux-staging@...ts.linux.dev
Subject: Re: [PATCH v1 07/19] staging: media: tegra-video: csi: parametrize
 MIPI calibration device presence

вт, 2 вер. 2025 р. о 03:47 Mikko Perttunen <mperttunen@...dia.com> пише:
>
> On Tuesday, August 19, 2025 9:16 PM Svyatoslav Ryhel wrote:
> > Dedicated MIPI calibration block appears only in Tegra114, before Tegra114
> > all MIPI calibration pads were part of VI block.
> >
> > Signed-off-by: Svyatoslav Ryhel <clamor95@...il.com>
> > ---
> >  drivers/staging/media/tegra-video/csi.c      | 12 +++++++-----
> >  drivers/staging/media/tegra-video/csi.h      |  1 +
> >  drivers/staging/media/tegra-video/tegra210.c |  1 +
> >  3 files changed, 9 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/staging/media/tegra-video/csi.c
> > b/drivers/staging/media/tegra-video/csi.c index 74c92db1032f..2f9907a20db1
> > 100644
> > --- a/drivers/staging/media/tegra-video/csi.c
> > +++ b/drivers/staging/media/tegra-video/csi.c
> > @@ -485,11 +485,13 @@ static int tegra_csi_channel_alloc(struct tegra_csi
> > *csi, if (IS_ENABLED(CONFIG_VIDEO_TEGRA_TPG))
> >               return 0;
> >
> > -     chan->mipi = tegra_mipi_request(csi->dev, node);
> > -     if (IS_ERR(chan->mipi)) {
> > -             ret = PTR_ERR(chan->mipi);
> > -             chan->mipi = NULL;
> > -             dev_err(csi->dev, "failed to get mipi device: %d\n", ret);
> > +     if (csi->soc->has_mipi_calibration) {
> > +             chan->mipi = tegra_mipi_request(csi->dev, node);
>
> The way I would read 'soc->has_mipi_calibration' is that this device (CSI)
> contains the MIPI calibration hardware. I.e. the opposite of here. I would
> invert the logic and optionally call it e.g. 'internal_mipi_calib'.
>
> A cleaner way to do this might be to always call tegra_mipi_request et al. --
> on pre-Tegra114 SoCs this would just call back to the VI/CSI driver using the
> callbacks registered in the MIPI driver as we discussed before. That way the
> CSI driver won't need separate code paths for SoCs with internal MIPI
> calibration and SoCs with the external MIPI calibration device.
>

So basically MIPI calibration device for Tegra20/Tegra30 has to be
created within CSI and when MIPI calibration is requested, CSI phandle
is used. Question: may I use a dedicated node for MIPI calibration
within CSI or it has to use CSI node itself? With dedicated node
configuration should be much simpler and can help avoiding probe of
entire.

> Cheers,
> Mikko
>
> > +             if (IS_ERR(chan->mipi)) {
> > +                     ret = PTR_ERR(chan->mipi);
> > +                     chan->mipi = NULL;
> > +                     dev_err(csi->dev, "failed to get mipi device:
> %d\n", ret);
> > +             }
> >       }
> >
> >       return ret;
> > diff --git a/drivers/staging/media/tegra-video/csi.h
> > b/drivers/staging/media/tegra-video/csi.h index 3ed2dbc73ce9..400b913bb1cb
> > 100644
> > --- a/drivers/staging/media/tegra-video/csi.h
> > +++ b/drivers/staging/media/tegra-video/csi.h
> > @@ -128,6 +128,7 @@ struct tegra_csi_soc {
> >       unsigned int num_clks;
> >       const struct tpg_framerate *tpg_frmrate_table;
> >       unsigned int tpg_frmrate_table_size;
> > +     bool has_mipi_calibration;
> >  };
> >
> >  /**
> > diff --git a/drivers/staging/media/tegra-video/tegra210.c
> > b/drivers/staging/media/tegra-video/tegra210.c index
> > da99f19a39e7..305472e94af4 100644
> > --- a/drivers/staging/media/tegra-video/tegra210.c
> > +++ b/drivers/staging/media/tegra-video/tegra210.c
> > @@ -1218,4 +1218,5 @@ const struct tegra_csi_soc tegra210_csi_soc = {
> >       .num_clks = ARRAY_SIZE(tegra210_csi_cil_clks),
> >       .tpg_frmrate_table = tegra210_tpg_frmrate_table,
> >       .tpg_frmrate_table_size = ARRAY_SIZE(tegra210_tpg_frmrate_table),
> > +     .has_mipi_calibration = true,
> >  };
>
>
>
>