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

Kieran Bingham
2017-05-04T14:59:47Z

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");
>