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Date:   Thu, 28 Apr 2022 13:43:44 +0200
From:   Paul Kocialkowski <paul.kocialkowski@bootlin.com>
To:     Maxime Ripard <maxime@cerno.tech>
Cc:     Jernej =?utf-8?Q?=C5=A0krabec?= <jernej.skrabec@gmail.com>,
        linux-kernel@vger.kernel.org, linux-media@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-sunxi@lists.linux.dev,
        Yong Deng <yong.deng@magewell.com>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        Chen-Yu Tsai <wens@csie.org>,
        Samuel Holland <samuel@sholland.org>,
        Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
        Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Subject: Re: [PATCH v4 43/45] media: sun6i-csi: Detect the availability of
 the ISP
Message-ID: <Ymp98LBQySvpz8/j@aptenodytes>
References: <20220415152811.636419-1-paul.kocialkowski@bootlin.com>
 <20220415152811.636419-44-paul.kocialkowski@bootlin.com>
 <2029179.KlZ2vcFHjT@jernej-laptop>
 <YmpIjPe8pw+yvGyL@aptenodytes>
 <20220428081130.6deusqgnrsgqdp3e@houat>
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Hi Maxime,

On Thu 28 Apr 22, 10:11, Maxime Ripard wrote:
> On Thu, Apr 28, 2022 at 09:55:56AM +0200, Paul Kocialkowski wrote:
> > Hi Jernej,
> >=20
> > Thanks a lot for all your reviews!
> >=20
> > On Wed 27 Apr 22, 22:07, Jernej =C5=A0krabec wrote:
> > > Dne petek, 15. april 2022 ob 17:28:09 CEST je Paul Kocialkowski napis=
al(a):
> > > > Add a helper to detect whether the ISP is available and connected
> > > > and store the indication in a driver-wide variable.
> > > >=20
> > > > Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
> > > > ---
> > > >  .../platform/sunxi/sun6i-csi/sun6i_csi.c      | 33 +++++++++++++++=
++++
> > > >  .../platform/sunxi/sun6i-csi/sun6i_csi.h      |  3 ++
> > > >  2 files changed, 36 insertions(+)
> > > >=20
> > > > diff --git a/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c
> > > > b/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c index
> > > > a88deb8ba1e7..f185cbd113c7 100644
> > > > --- a/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c
> > > > +++ b/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c
> > > > @@ -25,6 +25,35 @@
> > > >  #include "sun6i_csi_capture.h"
> > > >  #include "sun6i_csi_reg.h"
> > > >=20
> > > > +/* ISP */
> > > > +
> > > > +static bool sun6i_csi_isp_detect(struct sun6i_csi_device *csi_dev)
> > > > +{
> > > > +	struct device *dev =3D csi_dev->dev;
> > > > +	struct fwnode_handle *handle =3D NULL;
> > > > +
> > > > +	/* ISP is not available if disabled in kernel config. */
> > > > +	if (!IS_ENABLED(CONFIG_VIDEO_SUN6I_ISP))
> > >=20
> > > Where is this symbol defined?
> >=20
> > That is defined through Kconfig's auto-generated header, from the assoc=
iated
> > option for the ISP driver. It is defined in the ISP support series so t=
his
> > will effectively always be false for now.
>=20
> Can the ISP be compiled as a module, but the CSI driver built-in?

I think so yes, I don't see any reason why not.

> If so,
> that would create a dependency from the kernel image to a module, which
> won't compile.

I think this would introduce a run-time dependency (sun6i-csi needing sun6i=
-isp
in order to register) but I don't understand why it wouldn't compile though.
Could you ellaborate a bit?

Thanks!

Paul

--=20
Paul Kocialkowski, Bootlin
Embedded Linux and kernel engineering
https://bootlin.com

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