Re: [PATCH v1 2/6] media: imx-pxp: Add media controller support

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Michael,

On Thu, Jan 12, 2023 at 02:58:20PM +0100, Michael Tretter wrote:
> On Fri, 06 Jan 2023 15:32:23 +0200, Laurent Pinchart wrote:
> > Register a media device for the PXP, using the v4l2-mem2mem MC
> > infrastructure to populate the media graph. No media device operation is
> > implemented, the main use of the MC API is to allow consistent discovery
> > of media devices for userspace.
> > 
> > Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> > ---
> >  drivers/media/platform/nxp/imx-pxp.c | 37 ++++++++++++++++++++++++++++
> >  1 file changed, 37 insertions(+)
> > 
> > diff --git a/drivers/media/platform/nxp/imx-pxp.c b/drivers/media/platform/nxp/imx-pxp.c
> > index dcb04217288b..132065c8b8b4 100644
> > --- a/drivers/media/platform/nxp/imx-pxp.c
> > +++ b/drivers/media/platform/nxp/imx-pxp.c
> > @@ -24,6 +24,7 @@
> >  #include <linux/sched.h>
> >  #include <linux/slab.h>
> >  
> > +#include <media/media-device.h>
> >  #include <media/v4l2-ctrls.h>
> >  #include <media/v4l2-device.h>
> >  #include <media/v4l2-event.h>
> > @@ -200,6 +201,9 @@ struct pxp_pdata {
> >  struct pxp_dev {
> >  	struct v4l2_device	v4l2_dev;
> >  	struct video_device	vfd;
> > +#ifdef CONFIG_MEDIA_CONTROLLER
> > +	struct media_device	mdev;
> > +#endif
> >  
> >  	struct clk		*clk;
> >  	void __iomem		*mmio;
> > @@ -1832,8 +1836,36 @@ static int pxp_probe(struct platform_device *pdev)
> >  		goto err_m2m;
> >  	}
> >  
> > +#ifdef CONFIG_MEDIA_CONTROLLER
> > +	dev->mdev.dev = &pdev->dev;
> > +	strscpy(dev->mdev.model, MEM2MEM_NAME, sizeof(dev->mdev.model));
> > +	snprintf(dev->mdev.bus_info, sizeof(dev->mdev.bus_info), "platform:%s",
> > +		 dev_name(&pdev->dev));
> 
> v4l2-compliance gives the following warning:
> 
> 	warn: v4l2-compliance.cpp(642): media bus_info 'platform:30700000.pxp' differs from V4L2 bus_info 'platform:pxp'
> 
> I would change this patch to use the same name as in the V4L2 bus_info. Do you
> have a reason for including the address in the bus_info?

Actually, I should drop bus_info here. The documentation of
media_device_init() states

 * The bus_info field is set by media_device_init() for PCI and platform devices
 * if the field begins with '\0'.

media_device_init() calls media_set_bus_info() which is defined as

/**
 * media_set_bus_info() - Set bus_info field
 *
 * @bus_info:		Variable where to write the bus info (char array)
 * @bus_info_size:	Length of the bus_info
 * @dev:		Related struct device
 *
 * Sets bus information based on &dev. This is currently done for PCI and
 * platform devices. dev is required to be non-NULL for this to happen.
 *
 * This function is not meant to be called from drivers.
 */
static inline void
media_set_bus_info(char *bus_info, size_t bus_info_size, struct device *dev)
{
	if (!dev)
		strscpy(bus_info, "no bus info", bus_info_size);
	else if (dev_is_platform(dev))
		snprintf(bus_info, bus_info_size, "platform:%s", dev_name(dev));
	else if (dev_is_pci(dev))
		snprintf(bus_info, bus_info_size, "PCI:%s", dev_name(dev));
}

v4l_querycap() also calls media_set_bus_info(). Including the device
name is thus the recommended option.

I'll include in v2 another patch that drops the bus_info from the
video_device to make v4l2-compliance happy.

> > +	media_device_init(&dev->mdev);
> > +	dev->v4l2_dev.mdev = &dev->mdev;
> > +
> > +	ret = v4l2_m2m_register_media_controller(dev->m2m_dev, vfd,
> > +						 MEDIA_ENT_F_PROC_VIDEO_PIXEL_FORMATTER);
> > +	if (ret) {
> > +		dev_err(&pdev->dev, "Failed to initialize media device\n");
> > +		goto err_vfd;
> > +	}
> > +
> > +	ret = media_device_register(&dev->mdev);
> > +	if (ret) {
> > +		dev_err(&pdev->dev, "Failed to register media device\n");
> > +		goto err_m2m_mc;
> > +	}
> > +#endif
> > +
> >  	return 0;
> >  
> > +#ifdef CONFIG_MEDIA_CONTROLLER
> > +err_m2m_mc:
> > +	v4l2_m2m_unregister_media_controller(dev->m2m_dev);
> > +err_vfd:
> > +	video_unregister_device(vfd);
> > +#endif
> >  err_m2m:
> >  	v4l2_m2m_release(dev->m2m_dev);
> >  err_v4l2:
> > @@ -1854,6 +1886,11 @@ static int pxp_remove(struct platform_device *pdev)
> >  	clk_disable_unprepare(dev->clk);
> >  
> >  	v4l2_info(&dev->v4l2_dev, "Removing " MEM2MEM_NAME);
> > +
> > +#ifdef CONFIG_MEDIA_CONTROLLER
> > +	media_device_unregister(&dev->mdev);
> > +	v4l2_m2m_unregister_media_controller(dev->m2m_dev);
> > +#endif
> >  	video_unregister_device(&dev->vfd);
> >  	v4l2_m2m_release(dev->m2m_dev);
> >  	v4l2_device_unregister(&dev->v4l2_dev);

-- 
Regards,

Laurent Pinchart