linux-kernel - Re: [PATCH v4 43/45] media: sun6i-csi: Detect the availability of the ISP

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Message-ID: <5794263.alqRGMn8q6@jernej-laptop>
Date:   Thu, 28 Apr 2022 10:09:37 +0200
From:   Jernej Škrabec <jernej.skrabec@...il.com>
To:     Paul Kocialkowski <paul.kocialkowski@...tlin.com>
Cc:     linux-kernel@...r.kernel.org, linux-media@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-sunxi@...ts.linux.dev,
        Yong Deng <yong.deng@...ewell.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Chen-Yu Tsai <wens@...e.org>,
        Samuel Holland <samuel@...lland.org>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>
Subject: Re: [PATCH v4 43/45] media: sun6i-csi: Detect the availability of the ISP

Dne četrtek, 28. april 2022 ob 09:55:56 CEST je Paul Kocialkowski napisal(a):
> Hi Jernej,
> 
> Thanks a lot for all your reviews!
> 
> On Wed 27 Apr 22, 22:07, Jernej Škrabec wrote:
> > Dne petek, 15. april 2022 ob 17:28:09 CEST je Paul Kocialkowski 
napisal(a):
> > > Add a helper to detect whether the ISP is available and connected
> > > and store the indication in a driver-wide variable.
> > > 
> > > Signed-off-by: Paul Kocialkowski <paul.kocialkowski@...tlin.com>
> > > ---
> > > 
> > >  .../platform/sunxi/sun6i-csi/sun6i_csi.c      | 33 +++++++++++++++++++
> > >  .../platform/sunxi/sun6i-csi/sun6i_csi.h      |  3 ++
> > >  2 files changed, 36 insertions(+)
> > > 
> > > 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"
> > > 
> > > +/* ISP */
> > > +
> > > +static bool sun6i_csi_isp_detect(struct sun6i_csi_device *csi_dev)
> > > +{
> > > +	struct device *dev = csi_dev->dev;
> > > +	struct fwnode_handle *handle = NULL;
> > > +
> > > +	/* ISP is not available if disabled in kernel config. */
> > > +	if (!IS_ENABLED(CONFIG_VIDEO_SUN6I_ISP))
> > 
> > Where is this symbol defined?
> 
> That is defined through Kconfig's auto-generated header, from the associated
> option for the ISP driver. It is defined in the ISP support series so this
> will effectively always be false for now.

Well, then, that driver should be merged before this patch. While I understand 
that it's likely that ISP driver with such name will eventually materialize in 
kernel, I don't want to rely on things that are not set in stone, e.g. already 
merged.

Best regards,
Jernej

> 
> > Best regards,
> > Jernej
> > 
> > > +		return 0;
> > > +
> > > +	/*
> > > +	 * ISP is not available if not connected via fwnode graph.
> > > +	 * This weill also check that the remote parent node is available.
> > > +	 */
> > > +	handle = fwnode_graph_get_endpoint_by_id(dev_fwnode(dev),
> > > +
> > 
> > SUN6I_CSI_PORT_ISP, 0,
> > 
> > > +
> > 
> > FWNODE_GRAPH_ENDPOINT_NEXT);
> > 
> > > +	if (!handle)
> > > +		return 0;
> > > +
> > > +	fwnode_handle_put(handle);
> > > +
> > > +	dev_info(dev, "ISP link is available\n");
> > > +	csi_dev->isp_available = true;
> > > +
> > > +	return 0;
> > > +}
> > > +
> > > 
> > >  /* Media */
> > >  
> > >  static const struct media_device_ops sun6i_csi_media_ops = {
> > > 
> > > @@ -306,6 +335,10 @@ static int sun6i_csi_probe(struct platform_device
> > > *platform_dev) if (ret)
> > > 
> > >  		return ret;
> > > 
> > > +	ret = sun6i_csi_isp_detect(csi_dev);
> > > +	if (ret)
> > > +		goto error_resources;
> > > +
> > > 
> > >  	ret = sun6i_csi_v4l2_setup(csi_dev);
> > >  	if (ret)
> > >  	
> > >  		goto error_resources;
> > > 
> > > diff --git a/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.h
> > > b/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.h index
> > > 6aa83dd11684..9b105c341047 100644
> > > --- a/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.h
> > > +++ b/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.h
> > > @@ -22,6 +22,7 @@
> > > 
> > >  enum sun6i_csi_port {
> > >  
> > >  	SUN6I_CSI_PORT_PARALLEL		= 0,
> > >  	SUN6I_CSI_PORT_MIPI_CSI2	= 1,
> > > 
> > > +	SUN6I_CSI_PORT_ISP		= 2,
> > > 
> > >  };
> > >  
> > >  struct sun6i_csi_buffer {
> > > 
> > > @@ -46,6 +47,8 @@ struct sun6i_csi_device {
> > > 
> > >  	struct clk			*clock_mod;
> > >  	struct clk			*clock_ram;
> > >  	struct reset_control		*reset;
> > > 
> > > +
> > > +	bool				isp_available;
> > > 
> > >  };
> > >  
> > >  struct sun6i_csi_variant {