Re: [PATCH v3 2/2] [media] platform: add video-multiplexer subdevice driver

[Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>]

Hi Philipp,

Thankyou for the patch,

On 04/05/17 14:38, Philipp Zabel wrote:
> This driver can handle SoC internal and external video bus multiplexers,
> controlled by mux controllers provided by the mux controller framework,
> such as MMIO register bitfields or GPIOs. The subdevice passes through
> the mbus configuration of the active input to the output side.
> 
> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
> Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
> Signed-off-by: Steve Longerbeam <steve_longerbeam@mentor.com>
> ---
> Changes since v2 [1]:
>  - Extend vmux->lock to protect mbus format against simultaneous access
>    from get/set_format calls.
>  - Drop is_source_pad(), check pad->flags & MEDIA_PAD_FL_SOURCE directly.
>  - Replace v4l2_of_parse_endpoint call with v4l2_fwnode_endpoint_parse,
>    include media/v4l2-fwnode.h instead of media/v4l2-of.h.
>  - Constify ops structures.
> 
> This was previously sent as part of Steve's i.MX media series [2].
> Tested against
> https://git.linuxtv.org/sailus/media_tree.git/log/?h=v4l2-acpi-merge
> 
> [1] https://patchwork.kernel.org/patch/9708237/
> [2] https://patchwork.kernel.org/patch/9647869/
> ---
>  drivers/media/platform/Kconfig     |   6 +
>  drivers/media/platform/Makefile    |   2 +
>  drivers/media/platform/video-mux.c | 318 +++++++++++++++++++++++++++++++++++++
>  3 files changed, 326 insertions(+)
>  create mode 100644 drivers/media/platform/video-mux.c
> 
> diff --git a/drivers/media/platform/Kconfig b/drivers/media/platform/Kconfig
> index 317f8d41e4ad6..2fea699962624 100644
> --- a/drivers/media/platform/Kconfig
> +++ b/drivers/media/platform/Kconfig
> @@ -74,6 +74,12 @@ config VIDEO_M32R_AR_M64278
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called arv.
>  
> +config VIDEO_MUX
> +	tristate "Video Multiplexer"
> +	depends on OF && VIDEO_V4L2_SUBDEV_API && MEDIA_CONTROLLER && MULTIPLEXER
> +	help
> +	  This driver provides support for N:1 video bus multiplexers.
> +
>  config VIDEO_OMAP3
>  	tristate "OMAP 3 Camera support"
>  	depends on VIDEO_V4L2 && I2C && VIDEO_V4L2_SUBDEV_API && ARCH_OMAP3
> diff --git a/drivers/media/platform/Makefile b/drivers/media/platform/Makefile
> index 63303d63c64cf..a6363023f981e 100644
> --- a/drivers/media/platform/Makefile
> +++ b/drivers/media/platform/Makefile
> @@ -28,6 +28,8 @@ obj-$(CONFIG_VIDEO_SH_VEU)		+= sh_veu.o
>  
>  obj-$(CONFIG_VIDEO_MEM2MEM_DEINTERLACE)	+= m2m-deinterlace.o
>  
> +obj-$(CONFIG_VIDEO_MUX)			+= video-mux.o
> +
>  obj-$(CONFIG_VIDEO_S3C_CAMIF) 		+= s3c-camif/
>  obj-$(CONFIG_VIDEO_SAMSUNG_EXYNOS4_IS) 	+= exynos4-is/
>  obj-$(CONFIG_VIDEO_SAMSUNG_S5P_JPEG)	+= s5p-jpeg/
> diff --git a/drivers/media/platform/video-mux.c b/drivers/media/platform/video-mux.c
> new file mode 100644
> index 0000000000000..afa06febf6c33
> --- /dev/null
> +++ b/drivers/media/platform/video-mux.c
> @@ -0,0 +1,318 @@
> +/*
> + * video stream multiplexer controlled via mux control
> + *
> + * Copyright (C) 2013 Pengutronix, Sascha Hauer <kernel@pengutronix.de>
> + * Copyright (C) 2016-2017 Pengutronix, Philipp Zabel <kernel@pengutronix.de>
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License
> + * as published by the Free Software Foundation; either version 2
> + * of the License, or (at your option) any later version.
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + */
> +
> +#include <linux/err.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/mux/consumer.h>
> +#include <linux/of.h>
> +#include <linux/of_graph.h>
> +#include <linux/platform_device.h>
> +#include <media/v4l2-async.h>
> +#include <media/v4l2-device.h>
> +#include <media/v4l2-fwnode.h>
> +#include <media/v4l2-subdev.h>
> +
> +struct video_mux {
> +	struct v4l2_subdev subdev;
> +	struct media_pad *pads;
> +	struct v4l2_mbus_framefmt *format_mbus;
> +	struct v4l2_fwnode_endpoint *endpoint;
> +	struct mux_control *mux;
> +	struct mutex lock;
> +	int active;
> +};
> +
> +static inline struct video_mux *v4l2_subdev_to_video_mux(struct v4l2_subdev *sd)
> +{
> +	return container_of(sd, struct video_mux, subdev);
> +}
> +
> +static int video_mux_link_setup(struct media_entity *entity,
> +				const struct media_pad *local,
> +				const struct media_pad *remote, u32 flags)
> +{
> +	struct v4l2_subdev *sd = media_entity_to_v4l2_subdev(entity);
> +	struct video_mux *vmux = v4l2_subdev_to_video_mux(sd);
> +	int ret = 0;
> +
> +	/*
> +	 * The mux state is determined by the enabled sink pad link.
> +	 * Enabling or disabling the source pad link has no effect.
> +	 */
> +	if (local->flags & MEDIA_PAD_FL_SOURCE)
> +		return 0;
> +
> +	dev_dbg(sd->dev, "link setup '%s':%d->'%s':%d[%d]",
> +		remote->entity->name, remote->index, local->entity->name,
> +		local->index, flags & MEDIA_LNK_FL_ENABLED);
> +
> +	mutex_lock(&vmux->lock);
> +
> +	if (flags & MEDIA_LNK_FL_ENABLED) {
> +		if (vmux->active == local->index)
> +			goto out;
> +
> +		if (vmux->active >= 0) {
> +			ret = -EBUSY;
> +			goto out;
> +		}
> +
> +		dev_dbg(sd->dev, "setting %d active\n", local->index);
> +		ret = mux_control_try_select(vmux->mux, local->index);
> +		if (ret < 0)
> +			goto out;
> +		vmux->active = local->index;
> +	} else {
> +		if (vmux->active != local->index)
> +			goto out;
> +
> +		dev_dbg(sd->dev, "going inactive\n");
> +		mux_control_deselect(vmux->mux);
> +		vmux->active = -1;
> +	}
> +
> +out:
> +	mutex_unlock(&vmux->lock);
> +	return ret;
> +}
> +
> +static struct media_entity_operations video_mux_ops = {
> +	.link_setup = video_mux_link_setup,
> +	.link_validate = v4l2_subdev_link_validate,
> +};
> +
> +static bool video_mux_endpoint_disabled(struct device_node *ep)
> +{
> +	struct device_node *rpp = of_graph_get_remote_port_parent(ep);
> +
> +	return !of_device_is_available(rpp);
> +}
> +
> +static int video_mux_s_stream(struct v4l2_subdev *sd, int enable)
> +{
> +	struct video_mux *vmux = v4l2_subdev_to_video_mux(sd);
> +	struct v4l2_subdev *upstream_sd;
> +	struct media_pad *pad;
> +
> +	if (vmux->active == -1) {
> +		dev_err(sd->dev, "Can not start streaming on inactive mux\n");
> +		return -EINVAL;
> +	}
> +
> +	pad = media_entity_remote_pad(&sd->entity.pads[vmux->active]);
> +	if (!pad) {
> +		dev_err(sd->dev, "Failed to find remote source pad\n");
> +		return -ENOLINK;
> +	}
> +
> +	if (!is_media_entity_v4l2_subdev(pad->entity)) {
> +		dev_err(sd->dev, "Upstream entity is not a v4l2 subdev\n");
> +		return -ENODEV;
> +	}
> +
> +	upstream_sd = media_entity_to_v4l2_subdev(pad->entity);
> +
> +	return v4l2_subdev_call(upstream_sd, video, s_stream, enable);
> +}
> +
> +static const struct v4l2_subdev_video_ops video_mux_subdev_video_ops = {
> +	.s_stream = video_mux_s_stream,
> +};
> +
> +static struct v4l2_mbus_framefmt *
> +__video_mux_get_pad_format(struct v4l2_subdev *sd,
> +			   struct v4l2_subdev_pad_config *cfg,
> +			   unsigned int pad, u32 which)
> +{
> +	struct video_mux *vmux = v4l2_subdev_to_video_mux(sd);
> +
> +	switch (which) {
> +	case V4L2_SUBDEV_FORMAT_TRY:
> +		return v4l2_subdev_get_try_format(sd, cfg, pad);
> +	case V4L2_SUBDEV_FORMAT_ACTIVE:
> +		return &vmux->format_mbus[pad];
> +	default:
> +		return NULL;
> +	}
> +}
> +
> +static int video_mux_get_format(struct v4l2_subdev *sd,
> +			    struct v4l2_subdev_pad_config *cfg,
> +			    struct v4l2_subdev_format *sdformat)
> +{
> +	struct video_mux *vmux = v4l2_subdev_to_video_mux(sd);
> +
> +	mutex_lock(&vmux->lock);
> +
> +	sdformat->format = *__video_mux_get_pad_format(sd, cfg, sdformat->pad,
> +						   sdformat->which);
> +
> +	mutex_unlock(&vmux->lock);
> +
> +	return 0;
> +}
> +
> +static int video_mux_set_format(struct v4l2_subdev *sd,
> +			    struct v4l2_subdev_pad_config *cfg,
> +			    struct v4l2_subdev_format *sdformat)
> +{
> +	struct video_mux *vmux = v4l2_subdev_to_video_mux(sd);
> +	struct v4l2_mbus_framefmt *mbusformat;
> +	struct media_pad *pad = &vmux->pads[sdformat->pad];
> +
> +	mbusformat = __video_mux_get_pad_format(sd, cfg, sdformat->pad,
> +					    sdformat->which);
> +	if (!mbusformat)
> +		return -EINVAL;
> +
> +	mutex_lock(&vmux->lock);
> +
> +	/* Source pad mirrors active sink pad, no limitations on sink pads */
> +	if ((pad->flags & MEDIA_PAD_FL_SOURCE) && vmux->active >= 0)
> +		sdformat->format = vmux->format_mbus[vmux->active];
> +
> +	*mbusformat = sdformat->format;
> +
> +	mutex_unlock(&vmux->lock);
> +
> +	return 0;
> +}
> +
> +static const struct v4l2_subdev_pad_ops video_mux_pad_ops = {
> +	.get_fmt = video_mux_get_format,
> +	.set_fmt = video_mux_set_format,
> +};
> +
> +static const struct v4l2_subdev_ops video_mux_subdev_ops = {
> +	.pad = &video_mux_pad_ops,
> +	.video = &video_mux_subdev_video_ops,
> +};
> +
> +static int video_mux_probe(struct platform_device *pdev)
> +{
> +	struct device_node *np = pdev->dev.of_node;
> +	struct device *dev = &pdev->dev;
> +	struct device_node *ep;
> +	struct video_mux *vmux;
> +	unsigned int num_pads = 0;
> +	int ret;
> +	int i;
> +
> +	vmux = devm_kzalloc(dev, sizeof(*vmux), GFP_KERNEL);
> +	if (!vmux)
> +		return -ENOMEM;
> +
> +	platform_set_drvdata(pdev, vmux);
> +
> +	v4l2_subdev_init(&vmux->subdev, &video_mux_subdev_ops);
> +	snprintf(vmux->subdev.name, sizeof(vmux->subdev.name), "%s", np->name);
> +	vmux->subdev.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;
> +	vmux->subdev.dev = dev;
> +
> +	/*
> +	 * The largest numbered port is the output port. It determines
> +	 * total number of pads.
> +	 */
> +	for_each_endpoint_of_node(np, ep) {
> +		struct of_endpoint endpoint;
> +
> +		of_graph_parse_endpoint(ep, &endpoint);
> +		num_pads = max(num_pads, endpoint.port + 1);
> +	}
> +
> +	if (num_pads < 2) {
> +		dev_err(dev, "Not enough ports %d\n", num_pads);
> +		return -EINVAL;
> +	}
> +
> +	vmux->mux = devm_mux_control_get(dev, NULL);
> +	if (IS_ERR(vmux->mux)) {
> +		ret = PTR_ERR(vmux->mux);
> +		if (ret != -EPROBE_DEFER)
> +			dev_err(dev, "Failed to get mux: %d\n", ret);
> +		return ret;
> +	}
> +
> +	mutex_init(&vmux->lock);
> +	vmux->active = -1;
> +	vmux->pads = devm_kzalloc(dev, sizeof(*vmux->pads) * num_pads,
> +				  GFP_KERNEL);
> +	vmux->format_mbus = devm_kzalloc(dev, sizeof(*vmux->format_mbus) *
> +					 num_pads, GFP_KERNEL);
> +	vmux->endpoint = devm_kzalloc(dev, sizeof(*vmux->endpoint) *
> +				      (num_pads - 1), GFP_KERNEL);
> +
> +	for (i = 0; i < num_pads - 1; i++)
> +		vmux->pads[i].flags = MEDIA_PAD_FL_SINK;
> +	vmux->pads[num_pads - 1].flags = MEDIA_PAD_FL_SOURCE;
> +
> +	vmux->subdev.entity.function = MEDIA_ENT_F_VID_MUX;
> +	ret = media_entity_pads_init(&vmux->subdev.entity, num_pads,
> +				     vmux->pads);
> +	if (ret < 0)
> +		return ret;
> +
> +	vmux->subdev.entity.ops = &video_mux_ops;
> +
> +	for_each_endpoint_of_node(np, ep) {
> +		struct v4l2_fwnode_endpoint endpoint;
> +
> +		v4l2_fwnode_endpoint_parse(of_fwnode_handle(ep), &endpoint);
> +
> +		if (video_mux_endpoint_disabled(ep)) {
> +			dev_dbg(dev, "port %d disabled\n", endpoint.base.port);
> +			continue;
> +		}
> +
> +		vmux->endpoint[endpoint.base.port] = endpoint;

There is no verification here that endpoint.base.port is a valid value.
	( <= num_pads - 1 )

As it comes in from the DT, it 'could' be set as any arbitrary value. Should it
be sanity checked ? Or do we trust the DT at this point ?

> +	}
> +
> +	return v4l2_async_register_subdev(&vmux->subdev);
> +}
> +
> +static int video_mux_remove(struct platform_device *pdev)
> +{
> +	struct video_mux *vmux = platform_get_drvdata(pdev);
> +	struct v4l2_subdev *sd = &vmux->subdev;
> +
> +	v4l2_async_unregister_subdev(sd);
> +	media_entity_cleanup(&sd->entity);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id video_mux_dt_ids[] = {
> +	{ .compatible = "video-mux", },
> +	{ /* sentinel */ }
> +};
> +MODULE_DEVICE_TABLE(of, video_mux_dt_ids);
> +
> +static struct platform_driver video_mux_driver = {
> +	.probe		= video_mux_probe,
> +	.remove		= video_mux_remove,
> +	.driver		= {
> +		.of_match_table = video_mux_dt_ids,
> +		.name = "video-mux",
> +	},
> +};
> +
> +module_platform_driver(video_mux_driver);
> +
> +MODULE_DESCRIPTION("video stream multiplexer");
> +MODULE_AUTHOR("Sascha Hauer, Pengutronix");
> +MODULE_AUTHOR("Philipp Zabel, Pengutronix");
> +MODULE_LICENSE("GPL");
>