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SubjectRe: [PATCH v3 13/24] platform: add video-multiplexer subdevice driver
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Hi Hans,

On Fri, 2017-01-20 at 15:03 +0100, Hans Verkuil wrote:
> On 01/07/2017 03:11 AM, Steve Longerbeam wrote:
> > From: Philipp Zabel <p.zabel@pengutronix.de>
> >
> > This driver can handle SoC internal and external video bus multiplexers,
> > controlled either by register bit fields or by a GPIO. The subdevice
> > passes through frame interval and 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>
> >
> > --
> >
> > - fixed a cut&paste error in vidsw_remove(): v4l2_async_register_subdev()
> > should be unregister.
> >
> > - added media_entity_cleanup() and v4l2_device_unregister_subdev()
> > to vidsw_remove().
> >
> > - there was a line left over from a previous iteration that negated
> > the new way of determining the pad count just before it which
> > has been removed (num_pads = of_get_child_count(np)).
> >
> > - Philipp Zabel has developed a set of patches that allow adding
> > to the subdev async notifier waiting list using a chaining method
> > from the async registered callbacks (v4l2_of_subdev_registered()
> > and the prep patches for that). For now, I've removed the use of
> > v4l2_of_subdev_registered() for the vidmux driver's registered
> > callback. This doesn't affect the functionality of this driver,
> > but allows for it to be merged now, before adding the chaining
> > support.
> >
> > Signed-off-by: Steve Longerbeam <steve_longerbeam@mentor.com>
> > ---
> > .../bindings/media/video-multiplexer.txt | 59 +++
> > drivers/media/platform/Kconfig | 8 +
> > drivers/media/platform/Makefile | 2 +
> > drivers/media/platform/video-multiplexer.c | 472 +++++++++++++++++++++
> > 4 files changed, 541 insertions(+)
> > create mode 100644 Documentation/devicetree/bindings/media/video-multiplexer.txt
> > create mode 100644 drivers/media/platform/video-multiplexer.c
> >
> > diff --git a/Documentation/devicetree/bindings/media/video-multiplexer.txt b/Documentation/devicetree/bindings/media/video-multiplexer.txt
> > new file mode 100644
> > index 0000000..9d133d9
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/media/video-multiplexer.txt
> > @@ -0,0 +1,59 @@
> > +Video Multiplexer
> > +=================
> > +
> > +Video multiplexers allow to select between multiple input ports. Video received
> > +on the active input port is passed through to the output port. Muxes described
> > +by this binding may be controlled by a syscon register bitfield or by a GPIO.
> > +
> > +Required properties:
> > +- compatible : should be "video-multiplexer"
> > +- reg: should be register base of the register containing the control bitfield
> > +- bit-mask: bitmask of the control bitfield in the control register
> > +- bit-shift: bit offset of the control bitfield in the control register
> > +- gpios: alternatively to reg, bit-mask, and bit-shift, a single GPIO phandle
> > + may be given to switch between two inputs
> > +- #address-cells: should be <1>
> > +- #size-cells: should be <0>
> > +- port@*: at least three port nodes containing endpoints connecting to the
> > + source and sink devices according to of_graph bindings. The last port is
> > + the output port, all others are inputs.
> > +
> > +Example:
> > +
> > +syscon {
> > + compatible = "syscon", "simple-mfd";
> > +
> > + mux {
> > + compatible = "video-multiplexer";
> > + /* Single bit (1 << 19) in syscon register 0x04: */
> > + reg = <0x04>;
> > + bit-mask = <1>;
> > + bit-shift = <19>;
> > + #address-cells = <1>;
> > + #size-cells = <0>;
> > +
> > + port@0 {
> > + reg = <0>;
> > +
> > + mux_in0: endpoint {
> > + remote-endpoint = <&video_source0_out>;
> > + };
> > + };
> > +
> > + port@1 {
> > + reg = <1>;
> > +
> > + mux_in1: endpoint {
> > + remote-endpoint = <&video_source1_out>;
> > + };
> > + };
> > +
> > + port@2 {
> > + reg = <2>;
> > +
> > + mux_out: endpoint {
> > + remote-endpoint = <&capture_interface_in>;
> > + };
> > + };
> > + };
> > +};
> > diff --git a/drivers/media/platform/Kconfig b/drivers/media/platform/Kconfig
> > index d944421..65614b5 100644
> > --- a/drivers/media/platform/Kconfig
> > +++ b/drivers/media/platform/Kconfig
> > @@ -74,6 +74,14 @@ config VIDEO_M32R_AR_M64278
> > To compile this driver as a module, choose M here: the
> > module will be called arv.
> >
> > +config VIDEO_MULTIPLEXER
> > + tristate "Video Multiplexer"
> > + depends on VIDEO_V4L2_SUBDEV_API && MEDIA_CONTROLLER
> > + help
> > + This driver provides support for SoC internal N:1 video bus
> > + multiplexers controlled by register bitfields as well as external
> > + 2:1 video multiplexers controlled by a single GPIO.
> > +
> > 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 5b3cb27..7cf0ee5 100644
> > --- a/drivers/media/platform/Makefile
> > +++ b/drivers/media/platform/Makefile
> > @@ -27,6 +27,8 @@ obj-$(CONFIG_VIDEO_SH_VEU) += sh_veu.o
> >
> > obj-$(CONFIG_VIDEO_MEM2MEM_DEINTERLACE) += m2m-deinterlace.o
> >
> > +obj-$(CONFIG_VIDEO_MULTIPLEXER) += video-multiplexer.o
> > +
> > obj-$(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-multiplexer.c b/drivers/media/platform/video-multiplexer.c
> > new file mode 100644
> > index 0000000..48980c4
> > --- /dev/null
> > +++ b/drivers/media/platform/video-multiplexer.c
> > @@ -0,0 +1,472 @@
> > +/*
> > + * video stream multiplexer controlled via gpio or syscon
> > + *
> > + * Copyright (C) 2013 Pengutronix, Sascha Hauer <kernel@pengutronix.de>
> > + * Copyright (C) 2016 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/gpio/consumer.h>
> > +#include <linux/mfd/syscon.h>
> > +#include <linux/module.h>
> > +#include <linux/of.h>
> > +#include <linux/of_graph.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/regmap.h>
> > +#include <media/v4l2-async.h>
> > +#include <media/v4l2-device.h>
> > +#include <media/v4l2-subdev.h>
> > +#include <media/v4l2-of.h>
> > +
> > +struct vidsw {
> > + struct v4l2_subdev subdev;
> > + unsigned int num_pads;
> > + struct media_pad *pads;
> > + struct v4l2_mbus_framefmt *format_mbus;
> > + struct v4l2_fract timeperframe;
> > + struct v4l2_of_endpoint *endpoint;
> > + struct regmap_field *field;
> > + struct gpio_desc *gpio;
> > + int active;
> > +};
> > +
> > +static inline struct vidsw *v4l2_subdev_to_vidsw(struct v4l2_subdev *sd)
> > +{
> > + return container_of(sd, struct vidsw, subdev);
> > +}
> > +
> > +static void vidsw_set_active(struct vidsw *vidsw, int active)
> > +{
> > + vidsw->active = active;
> > + if (active < 0)
> > + return;
> > +
> > + dev_dbg(vidsw->subdev.dev, "setting %d active\n", active);
> > +
> > + if (vidsw->field)
> > + regmap_field_write(vidsw->field, active);
> > + else if (vidsw->gpio)
> > + gpiod_set_value(vidsw->gpio, active);
> > +}
> > +
> > +static int vidsw_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 vidsw *vidsw = v4l2_subdev_to_vidsw(sd);
> > +
> > + /* We have no limitations on enabling or disabling our output link */
> > + if (local->index == vidsw->num_pads - 1)
> > + return 0;
> > +
> > + dev_dbg(sd->dev, "link setup %s -> %s", remote->entity->name,
> > + local->entity->name);
> > +
> > + if (!(flags & MEDIA_LNK_FL_ENABLED)) {
> > + if (local->index == vidsw->active) {
> > + dev_dbg(sd->dev, "going inactive\n");
> > + vidsw->active = -1;
> > + }
> > + return 0;
> > + }
> > +
> > + if (vidsw->active >= 0) {
> > + struct media_pad *pad;
> > +
> > + if (vidsw->active == local->index)
> > + return 0;
> > +
> > + pad = media_entity_remote_pad(&vidsw->pads[vidsw->active]);
> > + if (pad) {
> > + struct media_link *link;
> > + int ret;
> > +
> > + link = media_entity_find_link(pad,
> > + &vidsw->pads[vidsw->active]);
> > + if (link) {
> > + ret = __media_entity_setup_link(link, 0);
> > + if (ret)
> > + return ret;
> > + }
> > + }
> > + }
> > +
> > + vidsw_set_active(vidsw, local->index);
> > +
> > + return 0;
> > +}
> > +
> > +static struct media_entity_operations vidsw_ops = {
> > + .link_setup = vidsw_link_setup,
> > +};
> > +
> > +static bool vidsw_endpoint_disabled(struct device_node *ep)
> > +{
> > + struct device_node *rpp;
> > +
> > + if (!of_device_is_available(ep))
> > + return true;
> > +
> > + rpp = of_graph_get_remote_port_parent(ep);
> > + if (!rpp)
> > + return true;
> > +
> > + return !of_device_is_available(rpp);
> > +}
> > +
> > +static int vidsw_async_init(struct vidsw *vidsw, struct device_node *node)
> > +{
> > + struct device_node *ep;
> > + u32 portno;
> > + int numports;
> > + int ret;
> > + int i;
> > + bool active_link = false;
> > +
> > + numports = vidsw->num_pads;
> > +
> > + for (i = 0; i < numports - 1; i++)
> > + vidsw->pads[i].flags = MEDIA_PAD_FL_SINK;
> > + vidsw->pads[numports - 1].flags = MEDIA_PAD_FL_SOURCE;
> > +
> > + vidsw->subdev.entity.function = MEDIA_ENT_F_MUX;
> > + ret = media_entity_pads_init(&vidsw->subdev.entity, numports,
> > + vidsw->pads);
> > + if (ret < 0)
> > + return ret;
> > +
> > + vidsw->subdev.entity.ops = &vidsw_ops;
> > +
> > + for_each_endpoint_of_node(node, ep) {
> > + struct v4l2_of_endpoint endpoint;
> > +
> > + v4l2_of_parse_endpoint(ep, &endpoint);
> > +
> > + portno = endpoint.base.port;
> > + if (portno >= numports - 1)
> > + continue;
> > +
> > + if (vidsw_endpoint_disabled(ep)) {
> > + dev_dbg(vidsw->subdev.dev, "port %d disabled\n", portno);
> > + continue;
> > + }
> > +
> > + vidsw->endpoint[portno] = endpoint;
> > +
> > + if (portno == vidsw->active)
> > + active_link = true;
> > + }
> > +
> > + for (portno = 0; portno < numports - 1; portno++) {
> > + if (!vidsw->endpoint[portno].base.local_node)
> > + continue;
> > +
> > + /* If the active input is not connected, use another */
> > + if (!active_link) {
> > + vidsw_set_active(vidsw, portno);
> > + active_link = true;
> > + }
> > + }
> > +
> > + return v4l2_async_register_subdev(&vidsw->subdev);
> > +}
> > +
> > +int vidsw_g_mbus_config(struct v4l2_subdev *sd, struct v4l2_mbus_config *cfg)
> > +{
> > + struct vidsw *vidsw = v4l2_subdev_to_vidsw(sd);
> > + struct media_pad *pad;
> > + int ret;
> > +
> > + if (vidsw->active == -1) {
> > + dev_err(sd->dev, "no configuration for inactive mux\n");
> > + return -EINVAL;
> > + }
> > +
> > + /*
> > + * Retrieve media bus configuration from the entity connected to the
> > + * active input
> > + */
> > + pad = media_entity_remote_pad(&vidsw->pads[vidsw->active]);
> > + if (pad) {
> > + sd = media_entity_to_v4l2_subdev(pad->entity);
> > + ret = v4l2_subdev_call(sd, video, g_mbus_config, cfg);
> > + if (ret == -ENOIOCTLCMD)
> > + pad = NULL;
> > + else if (ret < 0) {
> > + dev_err(sd->dev, "failed to get source configuration\n");
> > + return ret;
> > + }
> > + }
> > + if (!pad) {
> > + /* Mirror the input side on the output side */
> > + cfg->type = vidsw->endpoint[vidsw->active].bus_type;
> > + if (cfg->type == V4L2_MBUS_PARALLEL ||
> > + cfg->type == V4L2_MBUS_BT656)
> > + cfg->flags = vidsw->endpoint[vidsw->active].bus.parallel.flags;
> > + }
> > +
> > + return 0;
> > +}
>
> I am not certain this op is needed at all. In the current kernel this op is only
> used by soc_camera, pxa_camera and omap3isp (somewhat dubious). Normally this
> information should come from the device tree and there should be no need for this op.
>
> My (tentative) long-term plan was to get rid of this op.
>
> If you don't need it, then I recommend it is removed.

We currently use this to make the CSI capture interface understand
whether its source from the MIPI CSI-2 or from the parallel bus. That is
probably something that should be fixed, but I'm not quite sure how.

The Synopsys DesignWare MIPI CSI-2 reciever turns the incoming MIPI
CSI-2 signal into a 32-bit parallel pixel bus plus some signals for the
MIPI specific metadata (virtual channel, data type).

Then the CSI2IPU gasket turns this input bus into four separate parallel
16-bit pixel buses plus an 8-bit "mct_di" bus for each of them, that
carries the MIPI metadata. The incoming data is split into the four
outputs according to the MIPI virtual channel.

Two of these 16-bit + 8-bit parallel buses are routed through a
multiplexer before finally arriving at the CSI on the other side.

We need to configure the CSI to either use or ignore the data from the
8-bit mct_di bus depending on whether the source of the mux is
configured to the MIPI CSI-2 receiver / CSI2IPU gasket, or to a parallel
input.

Currently we let g_mbus_config pretend that even the internal 32-bit +
metadata and 16-bit + 8-bit metadata parallel buses are of type
V4L2_MBUS_CSI so that the CSI can ask the mux, which propagates to the
CSI-2 receiver, if connected.

Without g_mbus_config we'd need to get that information from somewhere
else. One possibility would be to extend MEDIA_BUS formats to describe
these "parallelized MIPI data" buses separately.

regards
Philipp

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