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Message-ID: <c51fcd39-b17a-48c3-9043-2e877ed29171@xs4all.nl>
Date: Wed, 28 Feb 2024 12:24:06 +0100
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Subject: Re: [PATCH v2 2/9] media: Add Chameleon v3 framebuffer driver
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To: =?UTF-8?Q?Pawe=C5=82_Anikiel?= <panikiel@google.com>, airlied@gmail.com,
 akpm@linux-foundation.org, conor+dt@kernel.org, daniel@ffwll.ch,
 dinguyen@kernel.org, krzysztof.kozlowski+dt@linaro.org,
 maarten.lankhorst@linux.intel.com, mchehab@kernel.org, mripard@kernel.org,
 robh+dt@kernel.org, tzimmermann@suse.de
Cc: devicetree@vger.kernel.org, dri-devel@lists.freedesktop.org,
 linux-kernel@vger.kernel.org, linux-media@vger.kernel.org,
 chromeos-krk-upstreaming@google.com, ribalda@chromium.org
References: <20240221160215.484151-1-panikiel@google.com>
 <20240221160215.484151-3-panikiel@google.com>
From: Hans Verkuil <hverkuil-cisco@xs4all.nl>
In-Reply-To: <20240221160215.484151-3-panikiel@google.com>
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Hi Paweł,

On 21/02/2024 17:02, Paweł Anikiel wrote:
> Add v4l2 driver for the Google Chameleon v3 framebuffer device.

This is just a video capture device, right? A framebuffer device is something
that lives in drivers/video/fbdev.

It is *very* confusing to see the term 'framebuffer' used in a video
capture context.

This commit log should also give a better description of the hardware.
Just a single one-liner is a bit on the short side :-)

> 
> Signed-off-by: Paweł Anikiel <panikiel@google.com>
> ---
>  drivers/media/platform/Kconfig                |   1 +
>  drivers/media/platform/Makefile               |   1 +
>  drivers/media/platform/google/Kconfig         |   3 +
>  drivers/media/platform/google/Makefile        |   2 +
>  .../media/platform/google/chameleonv3/Kconfig |  13 +
>  .../platform/google/chameleonv3/Makefile      |   3 +
>  .../platform/google/chameleonv3/chv3-fb.c     | 895 ++++++++++++++++++

chv3-video.c would be a much better name for chv3-fb.c.

That's a commonly used filename for video capture drivers.

>  7 files changed, 918 insertions(+)
>  create mode 100644 drivers/media/platform/google/Kconfig
>  create mode 100644 drivers/media/platform/google/Makefile
>  create mode 100644 drivers/media/platform/google/chameleonv3/Kconfig
>  create mode 100644 drivers/media/platform/google/chameleonv3/Makefile
>  create mode 100644 drivers/media/platform/google/chameleonv3/chv3-fb.c
> 
> diff --git a/drivers/media/platform/Kconfig b/drivers/media/platform/Kconfig
> index 91e54215de3a..b82f7b142b85 100644
> --- a/drivers/media/platform/Kconfig
> +++ b/drivers/media/platform/Kconfig
> @@ -69,6 +69,7 @@ source "drivers/media/platform/aspeed/Kconfig"
>  source "drivers/media/platform/atmel/Kconfig"
>  source "drivers/media/platform/cadence/Kconfig"
>  source "drivers/media/platform/chips-media/Kconfig"
> +source "drivers/media/platform/google/Kconfig"
>  source "drivers/media/platform/intel/Kconfig"
>  source "drivers/media/platform/marvell/Kconfig"
>  source "drivers/media/platform/mediatek/Kconfig"
> diff --git a/drivers/media/platform/Makefile b/drivers/media/platform/Makefile
> index 3296ec1ebe16..f7067eb05f76 100644
> --- a/drivers/media/platform/Makefile
> +++ b/drivers/media/platform/Makefile
> @@ -12,6 +12,7 @@ obj-y += aspeed/
>  obj-y += atmel/
>  obj-y += cadence/
>  obj-y += chips-media/
> +obj-y += google/
>  obj-y += intel/
>  obj-y += marvell/
>  obj-y += mediatek/
> diff --git a/drivers/media/platform/google/Kconfig b/drivers/media/platform/google/Kconfig
> new file mode 100644
> index 000000000000..2a5f01034c11
> --- /dev/null
> +++ b/drivers/media/platform/google/Kconfig
> @@ -0,0 +1,3 @@
> +# SPDX-License-Identifier: GPL-2.0-only
> +
> +source "drivers/media/platform/google/chameleonv3/Kconfig"
> diff --git a/drivers/media/platform/google/Makefile b/drivers/media/platform/google/Makefile
> new file mode 100644
> index 000000000000..c971a09faeb4
> --- /dev/null
> +++ b/drivers/media/platform/google/Makefile
> @@ -0,0 +1,2 @@
> +# SPDX-License-Identifier: GPL-2.0-only
> +obj-y += chameleonv3/
> diff --git a/drivers/media/platform/google/chameleonv3/Kconfig b/drivers/media/platform/google/chameleonv3/Kconfig
> new file mode 100644
> index 000000000000..76d0383a8589
> --- /dev/null
> +++ b/drivers/media/platform/google/chameleonv3/Kconfig
> @@ -0,0 +1,13 @@
> +# SPDX-License-Identifier: GPL-2.0-only
> +
> +config VIDEO_CHV3_FB
> +	tristate "Google Chameleon v3 framebuffer video driver"
> +	depends on V4L_PLATFORM_DRIVERS
> +	depends on VIDEO_DEV
> +	select VIDEOBUF2_DMA_CONTIG
> +	select V4L2_FWNODE
> +	help
> +	  v4l2 driver for the video interface present on the Google
> +	  Chameleon v3. The Chameleon v3 uses the framebuffer IP core
> +	  to take the video signal from different sources and directly
> +	  write frames into memory.

So it is composing different video streams into buffers? Or does it
capture from a single source at a time? The text is rather ambiguous.

> diff --git a/drivers/media/platform/google/chameleonv3/Makefile b/drivers/media/platform/google/chameleonv3/Makefile
> new file mode 100644
> index 000000000000..d63727148688
> --- /dev/null
> +++ b/drivers/media/platform/google/chameleonv3/Makefile
> @@ -0,0 +1,3 @@
> +# SPDX-License-Identifier: GPL-2.0-only
> +
> +obj-$(CONFIG_VIDEO_CHV3_FB) += chv3-fb.o
> diff --git a/drivers/media/platform/google/chameleonv3/chv3-fb.c b/drivers/media/platform/google/chameleonv3/chv3-fb.c
> new file mode 100644
> index 000000000000..35a44365eba0
> --- /dev/null
> +++ b/drivers/media/platform/google/chameleonv3/chv3-fb.c
> @@ -0,0 +1,895 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright 2023-2024 Google LLC.
> + * Author: Paweł Anikiel <panikiel@google.com>
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/dma-mapping.h>
> +#include <linux/interrupt.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/videodev2.h>
> +#include <media/v4l2-ctrls.h>
> +#include <media/v4l2-device.h>
> +#include <media/v4l2-dv-timings.h>
> +#include <media/v4l2-event.h>
> +#include <media/v4l2-fwnode.h>
> +#include <media/v4l2-ioctl.h>
> +#include <media/videobuf2-dma-contig.h>
> +
> +#define DEVICE_NAME	"chv3-fb"
> +
> +/*
> + * The device is expected to report some format even if there's currently no
> + * active video stream. In such case we default to 1080p.
> + */
> +#define DEFAULT_WIDTH	1920
> +#define DEFAULT_HEIGHT	1080
> +
> +#define FB_EN				0x00
> +#define FB_EN_BIT			BIT(0)
> +#define FB_HEIGHT			0x04
> +#define FB_WIDTH			0x08
> +#define FB_BUFFERA			0x0c
> +#define FB_BUFFERB			0x10
> +#define FB_BUFFERSIZE			0x14
> +#define FB_RESET			0x18
> +#define FB_RESET_BIT			BIT(0)
> +#define FB_ERRORSTATUS			0x1c
> +#define FB_IOCOLOR			0x20
> +#define FB_DATARATE			0x24
> +#define FB_DATARATE_SINGLE		0x0
> +#define FB_DATARATE_DOUBLE		0x1
> +#define FB_PIXELMODE			0x28
> +#define FB_PIXELMODE_SINGLE		0x0
> +#define FB_PIXELMODE_DOUBLE		0x1
> +#define FB_SYNCPOLARITY			0x2c
> +#define FB_DMAFORMAT			0x30
> +#define FB_DMAFORMAT_8BPC		0x0
> +#define FB_DMAFORMAT_10BPC_UPPER	0x1
> +#define FB_DMAFORMAT_10BPC_LOWER	0x2
> +#define FB_DMAFORMAT_12BPC_UPPER	0x3
> +#define FB_DMAFORMAT_12BPC_LOWER	0x4
> +#define FB_DMAFORMAT_16BPC		0x5
> +#define FB_DMAFORMAT_RAW		0x6
> +#define FB_DMAFORMAT_8BPC_LEGACY	0x7
> +#define FB_VERSION			0x34
> +#define FB_VERSION_CURRENT		0xc0fb0001
> +
> +#define FB_IRQ_MASK		0x8
> +#define FB_IRQ_CLR		0xc
> +#define FB_IRQ_ALL		0xf
> +#define FB_IRQ_BUFF0		BIT(0)
> +#define FB_IRQ_BUFF1		BIT(1)
> +#define FB_IRQ_RESOLUTION	BIT(2)
> +#define FB_IRQ_ERROR		BIT(3)
> +
> +struct chv3_fb {
> +	struct device *dev;
> +	void __iomem *iobase;
> +	void __iomem *iobase_irq;
> +
> +	struct v4l2_device v4l2_dev;
> +	struct vb2_queue queue;
> +	struct video_device vdev;
> +	struct v4l2_pix_format pix_fmt;
> +	struct v4l2_dv_timings timings;
> +
> +	struct v4l2_async_notifier notifier;
> +	struct v4l2_subdev *subdev;
> +	int subdev_source_pad;
> +
> +	u32 sequence;
> +	bool writing_to_a;
> +
> +	struct list_head bufs;
> +	spinlock_t bufs_lock;
> +
> +	struct mutex fb_lock;
> +};
> +
> +struct chv3_fb_buffer {
> +	struct vb2_v4l2_buffer vb;
> +	struct list_head link;
> +};
> +
> +static void chv3_fb_set_format_resolution(struct chv3_fb *fb, u32 width, u32 height)
> +{
> +	u32 bytes_per_pixel;
> +
> +	if (fb->pix_fmt.pixelformat == V4L2_PIX_FMT_RGB24)
> +		bytes_per_pixel = 3;
> +	else
> +		bytes_per_pixel = 4;
> +
> +	fb->pix_fmt.width = width;
> +	fb->pix_fmt.height = height;
> +	fb->pix_fmt.bytesperline = width * bytes_per_pixel;
> +	fb->pix_fmt.sizeimage = fb->pix_fmt.bytesperline * height;
> +}
> +
> +/*
> + * The video interface has hardware counters which expose the width and
> + * height of the current video stream. It can't reliably detect if the stream
> + * is present or not, so this is only used as a fallback in the case where
> + * we don't have access to the receiver hardware.
> + */
> +static int chv3_fb_query_dv_timings_fallback(struct chv3_fb *fb,
> +					     struct v4l2_dv_timings *timings)
> +{
> +	u32 width, height;
> +
> +	width  = readl(fb->iobase + FB_WIDTH);
> +	height = readl(fb->iobase + FB_HEIGHT);
> +	if (width == 0 || height == 0)
> +		return -ENOLINK;
> +
> +	memset(timings, 0, sizeof(*timings));
> +	timings->type = V4L2_DV_BT_656_1120;
> +	timings->bt.width  = width;
> +	timings->bt.height = height;
> +
> +	return 0;
> +}
> +
> +static int chv3_fb_query_dv_timings(struct chv3_fb *fb, struct v4l2_dv_timings *timings)
> +{
> +	if (fb->subdev) {
> +		return v4l2_subdev_call(fb->subdev, pad, query_dv_timings,
> +					fb->subdev_source_pad, timings);
> +	} else {
> +		return chv3_fb_query_dv_timings_fallback(fb, timings);
> +	}
> +}
> +
> +static const struct v4l2_dv_timings_cap chv3_fb_fallback_dv_timings_cap = {
> +	.type = V4L2_DV_BT_656_1120,
> +	.bt = {
> +		.min_width = 0,

This is an unlikely minimum width (ditto for height below).

> +		.max_width = 65535,

The max is suspect as well: I would expect it to be a multiple of 2/4/8/16.

> +		.min_height = 0,
> +		.max_height = 65535,
> +		.min_pixelclock = 0,
> +		.max_pixelclock = 2147483647,

Ditto for these.

> +		.standards = V4L2_DV_BT_STD_CEA861 | V4L2_DV_BT_STD_DMT |
> +			V4L2_DV_BT_STD_CVT | V4L2_DV_BT_STD_GTF,
> +		.capabilities = V4L2_DV_BT_CAP_PROGRESSIVE |
> +			V4L2_DV_BT_CAP_REDUCED_BLANKING |
> +			V4L2_DV_BT_CAP_CUSTOM,
> +	},
> +};
> +
> +static int chv3_fb_enum_dv_timings_fallback(struct chv3_fb *fb,
> +					    struct v4l2_enum_dv_timings *timings)
> +{
> +	return v4l2_enum_dv_timings_cap(timings, &chv3_fb_fallback_dv_timings_cap,
> +					NULL, NULL);
> +}
> +
> +static int chv3_fb_dv_timings_cap_fallback(struct chv3_fb *fb,
> +					   struct v4l2_dv_timings_cap *cap)
> +{
> +	*cap = chv3_fb_fallback_dv_timings_cap;
> +
> +	return 0;
> +}
> +
> +static void chv3_fb_apply_dv_timings(struct chv3_fb *fb)
> +{
> +	struct v4l2_dv_timings timings;
> +	int res;
> +
> +	res = chv3_fb_query_dv_timings(fb, &timings);
> +	if (res)
> +		return;
> +
> +	fb->timings = timings;
> +	chv3_fb_set_format_resolution(fb, timings.bt.width, timings.bt.height);
> +}
> +
> +static int chv3_fb_querycap(struct file *file, void *fh,
> +			    struct v4l2_capability *cap)
> +{
> +	strscpy(cap->driver, DEVICE_NAME, sizeof(cap->driver));
> +	strscpy(cap->card, "Chameleon v3 video", sizeof(cap->card));
> +
> +	return 0;
> +}
> +
> +static int chv3_fb_g_fmt_vid_cap(struct file *file, void *fh,
> +				 struct v4l2_format *fmt)
> +{
> +	struct chv3_fb *fb = video_drvdata(file);
> +
> +	fmt->fmt.pix = fb->pix_fmt;
> +
> +	return 0;
> +}
> +
> +static int chv3_fb_enum_fmt_vid_cap(struct file *file, void *fh,
> +				    struct v4l2_fmtdesc *fmt)
> +{
> +	struct chv3_fb *fb = video_drvdata(file);
> +
> +	if (fmt->index != 0)
> +		return -EINVAL;
> +
> +	fmt->flags = 0;
> +	fmt->pixelformat = fb->pix_fmt.pixelformat;
> +
> +	return 0;
> +}
> +
> +static int chv3_fb_enum_framesizes(struct file *file, void *fh,
> +				   struct v4l2_frmsizeenum *frm)
> +{
> +	struct chv3_fb *fb = video_drvdata(file);
> +
> +	if (frm->index != 0)
> +		return -EINVAL;
> +
> +	if (frm->pixel_format != fb->pix_fmt.pixelformat)
> +		return -EINVAL;
> +
> +	frm->type = V4L2_FRMSIZE_TYPE_DISCRETE;
> +	frm->discrete.width  = fb->pix_fmt.width;
> +	frm->discrete.height = fb->pix_fmt.height;

This is not something you would expect to see supported for a
video receiver input. This is something you use for camera sensors.

This should almost certainly be dropped.

> +
> +	return 0;
> +}
> +
> +static int chv3_fb_g_input(struct file *file, void *fh, unsigned int *index)
> +{
> +	*index = 0;
> +
> +	return 0;
> +}
> +
> +static int chv3_fb_s_input(struct file *file, void *fh, unsigned int index)
> +{
> +	if (index != 0)
> +		return -EINVAL;
> +
> +	return 0;
> +}
> +
> +static int chv3_fb_enum_input(struct file *file, void *fh,
> +			      struct v4l2_input *input)
> +{
> +	if (input->index != 0)
> +		return -EINVAL;
> +
> +	strscpy(input->name, "input0", sizeof(input->name));
> +	input->type = V4L2_INPUT_TYPE_CAMERA;
> +	input->capabilities = V4L2_IN_CAP_DV_TIMINGS;
> +
> +	return 0;
> +}
> +
> +static int chv3_fb_g_edid(struct file *file, void *fh,
> +			  struct v4l2_edid *edid)
> +{
> +	struct chv3_fb *fb = video_drvdata(file);
> +	int res;
> +
> +	if (!fb->subdev)
> +		return -ENOTTY;
> +
> +	if (edid->pad != 0)
> +		return -EINVAL;
> +
> +	edid->pad = fb->subdev_source_pad;
> +	res = v4l2_subdev_call(fb->subdev, pad, get_edid, edid);
> +	edid->pad = 0;
> +
> +	return res;
> +}
> +
> +static int chv3_fb_s_edid(struct file *file, void *fh,
> +			  struct v4l2_edid *edid)
> +{
> +	struct chv3_fb *fb = video_drvdata(file);
> +	int res;
> +
> +	if (!fb->subdev)
> +		return -ENOTTY;
> +
> +	if (edid->pad != 0)
> +		return -EINVAL;
> +
> +	edid->pad = fb->subdev_source_pad;
> +	res = v4l2_subdev_call(fb->subdev, pad, set_edid, edid);
> +	edid->pad = 0;
> +
> +	return res;
> +}
> +
> +static int chv3_fb_s_dv_timings(struct file *file, void *fh,
> +				struct v4l2_dv_timings *timings)
> +{
> +	struct chv3_fb *fb = video_drvdata(file);
> +
> +	if (timings->bt.width == fb->timings.bt.width &&
> +	    timings->bt.height == fb->timings.bt.height)

You would typically use v4l2_match_dv_timings() for this. The check above
is insufficient since it does not even check for different framerates or
interlaced vs progressive.

> +		return 0;
> +
> +	if (vb2_is_busy(&fb->queue))
> +		return -EBUSY;
> +
> +	if (!v4l2_valid_dv_timings(timings, &chv3_fb_fallback_dv_timings_cap, NULL, NULL))
> +		return -ERANGE;
> +
> +	fb->timings = *timings;
> +	chv3_fb_set_format_resolution(fb, timings->bt.width, timings->bt.height);
> +
> +	return 0;
> +}
> +
> +static int chv3_fb_g_dv_timings(struct file *file, void *fh,
> +				struct v4l2_dv_timings *timings)
> +{
> +	struct chv3_fb *fb = video_drvdata(file);
> +
> +	*timings = fb->timings;
> +	return 0;
> +}
> +
> +static int chv3_fb_vidioc_query_dv_timings(struct file *file, void *fh,
> +					   struct v4l2_dv_timings *timings)
> +{
> +	struct chv3_fb *fb = video_drvdata(file);
> +
> +	return chv3_fb_query_dv_timings(fb, timings);
> +}
> +
> +static int chv3_fb_enum_dv_timings(struct file *file, void *fh,
> +				   struct v4l2_enum_dv_timings *timings)
> +{
> +	struct chv3_fb *fb = video_drvdata(file);
> +	int res;
> +
> +	if (timings->pad != 0)
> +		return -EINVAL;
> +
> +	if (fb->subdev) {
> +		timings->pad = fb->subdev_source_pad;
> +		res = v4l2_subdev_call(fb->subdev, pad, enum_dv_timings, timings);
> +		timings->pad = 0;
> +		return res;
> +	} else {
> +		return chv3_fb_enum_dv_timings_fallback(fb, timings);
> +	}
> +}
> +
> +static int chv3_fb_dv_timings_cap(struct file *file, void *fh,
> +				  struct v4l2_dv_timings_cap *cap)
> +{
> +	struct chv3_fb *fb = video_drvdata(file);
> +	int res;
> +
> +	if (cap->pad != 0)
> +		return -EINVAL;
> +
> +	if (fb->subdev) {
> +		cap->pad = fb->subdev_source_pad;
> +		res = v4l2_subdev_call(fb->subdev, pad, dv_timings_cap, cap);
> +		cap->pad = 0;
> +		return res;
> +	} else {
> +		return chv3_fb_dv_timings_cap_fallback(fb, cap);
> +	}
> +}
> +
> +static int chv3_fb_subscribe_event(struct v4l2_fh *fh,
> +				   const struct v4l2_event_subscription *sub)
> +{
> +	switch (sub->type) {
> +	case V4L2_EVENT_SOURCE_CHANGE:
> +		return v4l2_src_change_event_subscribe(fh, sub);
> +	}
> +
> +	return v4l2_ctrl_subscribe_event(fh, sub);
> +}

I am missing support for the V4L2_CID_DV_RX_POWER_PRESENT control:

https://hverkuil.home.xs4all.nl/spec/userspace-api/v4l/ext-ctrls-dv.html

> +
> +static const struct v4l2_ioctl_ops chv3_fb_v4l2_ioctl_ops = {
> +	.vidioc_querycap = chv3_fb_querycap,
> +
> +	.vidioc_enum_fmt_vid_cap = chv3_fb_enum_fmt_vid_cap,
> +	.vidioc_g_fmt_vid_cap = chv3_fb_g_fmt_vid_cap,
> +	.vidioc_s_fmt_vid_cap = chv3_fb_g_fmt_vid_cap,
> +	.vidioc_try_fmt_vid_cap = chv3_fb_g_fmt_vid_cap,
> +
> +	.vidioc_enum_framesizes = chv3_fb_enum_framesizes,
> +
> +	.vidioc_enum_input = chv3_fb_enum_input,
> +	.vidioc_g_input = chv3_fb_g_input,
> +	.vidioc_s_input = chv3_fb_s_input,
> +	.vidioc_g_edid = chv3_fb_g_edid,
> +	.vidioc_s_edid = chv3_fb_s_edid,
> +
> +	.vidioc_reqbufs = vb2_ioctl_reqbufs,
> +	.vidioc_create_bufs = vb2_ioctl_create_bufs,
> +	.vidioc_querybuf = vb2_ioctl_querybuf,
> +	.vidioc_prepare_buf = vb2_ioctl_prepare_buf,
> +	.vidioc_expbuf = vb2_ioctl_expbuf,
> +	.vidioc_qbuf = vb2_ioctl_qbuf,
> +	.vidioc_dqbuf = vb2_ioctl_dqbuf,
> +	.vidioc_streamon = vb2_ioctl_streamon,
> +	.vidioc_streamoff = vb2_ioctl_streamoff,
> +
> +	.vidioc_s_dv_timings = chv3_fb_s_dv_timings,
> +	.vidioc_g_dv_timings = chv3_fb_g_dv_timings,
> +	.vidioc_query_dv_timings = chv3_fb_vidioc_query_dv_timings,
> +	.vidioc_enum_dv_timings = chv3_fb_enum_dv_timings,
> +	.vidioc_dv_timings_cap = chv3_fb_dv_timings_cap,
> +
> +	.vidioc_subscribe_event = chv3_fb_subscribe_event,
> +	.vidioc_unsubscribe_event = v4l2_event_unsubscribe,
> +};
> +
> +static int chv3_fb_queue_setup(struct vb2_queue *q,
> +			       unsigned int *nbuffers, unsigned int *nplanes,
> +			       unsigned int sizes[], struct device *alloc_devs[])
> +{
> +	struct chv3_fb *fb = vb2_get_drv_priv(q);
> +
> +	if (*nplanes) {
> +		if (sizes[0] < fb->pix_fmt.sizeimage)
> +			return -EINVAL;
> +		return 0;
> +	}
> +	*nplanes = 1;
> +	sizes[0] = fb->pix_fmt.sizeimage;
> +
> +	return 0;
> +}
> +
> +/*
> + * There are two address registers: BUFFERA and BUFFERB. The framebuffer
> + * alternates writing between them (i.e. even frames go to BUFFERA, odd
> + * ones to BUFFERB).
> + *
> + *  (buffer queue) >     QUEUED ---> QUEUED ---> QUEUED ---> ...
> + *                       BUFFERA     BUFFERB
> + *  (hw writing to this) ^
> + *                (and then to this) ^
> + *
> + * The buffer swapping happens at irq time. When an irq comes, the next
> + * frame is already assigned an address in the buffer queue. This gives
> + * the irq handler a whole frame's worth of time to update the buffer
> + * address register.
> + */
> +
> +static dma_addr_t chv3_fb_buffer_dma_addr(struct chv3_fb_buffer *buf)
> +{
> +	return vb2_dma_contig_plane_dma_addr(&buf->vb.vb2_buf, 0);
> +}
> +
> +static void chv3_fb_start_frame(struct chv3_fb *fb, struct chv3_fb_buffer *buf)
> +{
> +	fb->writing_to_a = 1;
> +	writel(chv3_fb_buffer_dma_addr(buf), fb->iobase + FB_BUFFERA);
> +	writel(FB_EN_BIT, fb->iobase + FB_EN);
> +}
> +
> +static void chv3_fb_next_frame(struct chv3_fb *fb, struct chv3_fb_buffer *buf)
> +{
> +	u32 reg = fb->writing_to_a ? FB_BUFFERB : FB_BUFFERA;
> +
> +	writel(chv3_fb_buffer_dma_addr(buf), fb->iobase + reg);
> +}
> +
> +static int chv3_fb_start_streaming(struct vb2_queue *q, unsigned int count)
> +{
> +	struct chv3_fb *fb = vb2_get_drv_priv(q);
> +	struct chv3_fb_buffer *buf;
> +	unsigned long flags;
> +
> +	fb->sequence = 0;
> +	writel(fb->pix_fmt.sizeimage, fb->iobase + FB_BUFFERSIZE);
> +
> +	spin_lock_irqsave(&fb->bufs_lock, flags);
> +	buf = list_first_entry_or_null(&fb->bufs, struct chv3_fb_buffer, link);
> +	if (buf) {
> +		chv3_fb_start_frame(fb, buf);
> +		if (!list_is_last(&buf->link, &fb->bufs))
> +			chv3_fb_next_frame(fb, list_next_entry(buf, link));
> +	}
> +	spin_unlock_irqrestore(&fb->bufs_lock, flags);
> +
> +	return 0;
> +}
> +
> +static void chv3_fb_stop_streaming(struct vb2_queue *q)
> +{
> +	struct chv3_fb *fb = vb2_get_drv_priv(q);
> +	struct chv3_fb_buffer *buf;
> +	unsigned long flags;
> +
> +	writel(0, fb->iobase + FB_EN);
> +
> +	spin_lock_irqsave(&fb->bufs_lock, flags);
> +	list_for_each_entry(buf, &fb->bufs, link)
> +		vb2_buffer_done(&buf->vb.vb2_buf, VB2_BUF_STATE_ERROR);
> +	INIT_LIST_HEAD(&fb->bufs);
> +	spin_unlock_irqrestore(&fb->bufs_lock, flags);
> +}
> +
> +static void chv3_fb_buf_queue(struct vb2_buffer *vb)
> +{
> +	struct chv3_fb *fb = vb2_get_drv_priv(vb->vb2_queue);
> +	struct vb2_v4l2_buffer *v4l2_buf = to_vb2_v4l2_buffer(vb);
> +	struct chv3_fb_buffer *buf = container_of(v4l2_buf, struct chv3_fb_buffer, vb);
> +	bool first, second;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&fb->bufs_lock, flags);
> +	first = list_empty(&fb->bufs);
> +	second = list_is_singular(&fb->bufs);
> +	list_add_tail(&buf->link, &fb->bufs);
> +	if (vb2_is_streaming(vb->vb2_queue)) {
> +		if (first)
> +			chv3_fb_start_frame(fb, buf);
> +		else if (second)
> +			chv3_fb_next_frame(fb, buf);
> +	}
> +	spin_unlock_irqrestore(&fb->bufs_lock, flags);
> +}
> +
> +static const struct vb2_ops chv3_fb_vb2_ops = {
> +	.queue_setup = chv3_fb_queue_setup,
> +	.wait_prepare = vb2_ops_wait_prepare,
> +	.wait_finish = vb2_ops_wait_finish,
> +	.start_streaming = chv3_fb_start_streaming,
> +	.stop_streaming = chv3_fb_stop_streaming,
> +	.buf_queue = chv3_fb_buf_queue,
> +};
> +
> +static int chv3_fb_open(struct file *file)
> +{
> +	struct chv3_fb *fb = video_drvdata(file);
> +	int res;
> +
> +	mutex_lock(&fb->fb_lock);
> +	res = v4l2_fh_open(file);
> +	if (!res) {
> +		if (v4l2_fh_is_singular_file(file))
> +			chv3_fb_apply_dv_timings(fb);
> +	}
> +	mutex_unlock(&fb->fb_lock);
> +
> +	return res;
> +}
> +
> +static const struct v4l2_file_operations chv3_fb_v4l2_fops = {
> +	.owner = THIS_MODULE,
> +	.open = chv3_fb_open,
> +	.release = vb2_fop_release,
> +	.unlocked_ioctl = video_ioctl2,
> +	.mmap = vb2_fop_mmap,
> +	.poll = vb2_fop_poll,
> +};
> +
> +static void chv3_fb_frame_irq(struct chv3_fb *fb)
> +{
> +	struct chv3_fb_buffer *buf;
> +
> +	spin_lock(&fb->bufs_lock);
> +
> +	buf = list_first_entry_or_null(&fb->bufs, struct chv3_fb_buffer, link);
> +	if (!buf)
> +		goto empty;
> +	list_del(&buf->link);
> +
> +	vb2_set_plane_payload(&buf->vb.vb2_buf, 0, fb->pix_fmt.sizeimage);
> +	buf->vb.vb2_buf.timestamp = ktime_get_ns();
> +	buf->vb.sequence = fb->sequence++;
> +	buf->vb.field = V4L2_FIELD_NONE;
> +	vb2_buffer_done(&buf->vb.vb2_buf, VB2_BUF_STATE_DONE);
> +
> +	buf = list_first_entry_or_null(&fb->bufs, struct chv3_fb_buffer, link);
> +	if (buf) {
> +		fb->writing_to_a = !fb->writing_to_a;
> +		if (!list_is_last(&buf->link, &fb->bufs))
> +			chv3_fb_next_frame(fb, list_next_entry(buf, link));
> +	} else {
> +		writel(0, fb->iobase + FB_EN);
> +	}
> +empty:
> +	spin_unlock(&fb->bufs_lock);
> +}
> +
> +static void chv3_fb_error_irq(struct chv3_fb *fb)
> +{
> +	if (vb2_is_streaming(&fb->queue))
> +		vb2_queue_error(&fb->queue);
> +}
> +
> +static void chv3_fb_resolution_irq(struct chv3_fb *fb)
> +{
> +	static const struct v4l2_event event = {
> +		.type = V4L2_EVENT_SOURCE_CHANGE,
> +		.u.src_change.changes = V4L2_EVENT_SRC_CH_RESOLUTION,
> +	};
> +
> +	v4l2_event_queue(&fb->vdev, &event);
> +	chv3_fb_error_irq(fb);
> +}
> +
> +static irqreturn_t chv3_fb_isr(int irq, void *data)
> +{
> +	struct chv3_fb *fb = data;
> +	unsigned int reg;
> +
> +	reg = readl(fb->iobase_irq + FB_IRQ_CLR);
> +	if (!reg)
> +		return IRQ_NONE;
> +
> +	if (reg & FB_IRQ_BUFF0)
> +		chv3_fb_frame_irq(fb);
> +	if (reg & FB_IRQ_BUFF1)
> +		chv3_fb_frame_irq(fb);
> +	if (reg & FB_IRQ_RESOLUTION)
> +		chv3_fb_resolution_irq(fb);
> +	if (reg & FB_IRQ_ERROR) {
> +		dev_warn(fb->dev, "framebuffer error: 0x%x\n",
> +			 readl(fb->iobase + FB_ERRORSTATUS));
> +		chv3_fb_error_irq(fb);
> +	}
> +
> +	writel(reg, fb->iobase_irq + FB_IRQ_CLR);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static int chv3_fb_check_version(struct chv3_fb *fb)
> +{
> +	u32 version;
> +
> +	version = readl(fb->iobase + FB_VERSION);
> +	if (version != FB_VERSION_CURRENT) {
> +		dev_err(fb->dev,
> +			"wrong framebuffer version: expected %x, got %x\n",
> +			FB_VERSION_CURRENT, version);
> +		return -ENODEV;
> +	}
> +	return 0;
> +}
> +
> +static void chv3_fb_set_default_format(struct chv3_fb *fb, bool legacy_format)
> +{
> +	struct v4l2_pix_format *pix = &fb->pix_fmt;
> +
> +	if (legacy_format)
> +		pix->pixelformat = V4L2_PIX_FMT_BGRX32;
> +	else
> +		pix->pixelformat = V4L2_PIX_FMT_RGB24;
> +	pix->field = V4L2_FIELD_NONE;
> +	pix->colorspace = V4L2_COLORSPACE_SRGB;
> +
> +	chv3_fb_set_format_resolution(fb, DEFAULT_WIDTH, DEFAULT_HEIGHT);
> +}
> +
> +static void chv3_fb_set_default_timings(struct chv3_fb *fb)
> +{
> +	memset(&fb->timings, 0, sizeof(fb->timings));
> +	fb->timings.type = V4L2_DV_BT_656_1120;
> +	fb->timings.bt.width  = DEFAULT_WIDTH;
> +	fb->timings.bt.height = DEFAULT_HEIGHT;

Wouldn't it be better to say: fb->timings = V4L2_DV_BT_CEA_1920X1080P60;

> +}
> +
> +#define notifier_to_fb(nf) container_of(nf, struct chv3_fb, notifier)
> +
> +static int chv3_fb_async_notify_bound(struct v4l2_async_notifier *notifier,
> +				      struct v4l2_subdev *subdev,
> +				      struct v4l2_async_connection *asc)
> +{
> +	struct chv3_fb *fb = notifier_to_fb(notifier);
> +	int pad;
> +
> +	pad = media_entity_get_fwnode_pad(&subdev->entity, asc->match.fwnode,
> +					  MEDIA_PAD_FL_SOURCE);
> +	if (pad < 0)
> +		return pad;
> +
> +	fb->subdev = subdev;
> +	fb->subdev_source_pad = pad;
> +
> +	return 0;
> +}
> +
> +static void chv3_fb_async_notify_unbind(struct v4l2_async_notifier *notifier,
> +					struct v4l2_subdev *subdev,
> +					struct v4l2_async_connection *asc)
> +{
> +	struct chv3_fb *fb = notifier_to_fb(notifier);
> +
> +	video_unregister_device(&fb->vdev);

Use vb2_video_unregister_device. See documentation in include/media/videobuf2-v4l2.h.

> +}
> +
> +static int chv3_fb_async_notify_complete(struct v4l2_async_notifier *notifier)
> +{
> +	struct chv3_fb *fb = notifier_to_fb(notifier);
> +
> +	return video_register_device(&fb->vdev, VFL_TYPE_VIDEO, -1);
> +}
> +
> +static const struct v4l2_async_notifier_operations chv3_fb_async_notify_ops = {
> +	.bound = chv3_fb_async_notify_bound,
> +	.unbind = chv3_fb_async_notify_unbind,
> +	.complete = chv3_fb_async_notify_complete,
> +};
> +
> +static int chv3_fb_fallback_init(struct chv3_fb *fb)
> +{
> +	fb->subdev = NULL;
> +	fb->subdev_source_pad = 0;
> +
> +	return video_register_device(&fb->vdev, VFL_TYPE_VIDEO, -1);
> +}
> +
> +static int chv3_fb_fwnode_init(struct chv3_fb *fb)
> +{
> +	struct v4l2_async_connection *asc;
> +	struct fwnode_handle *endpoint;
> +	int res;
> +
> +	endpoint = fwnode_graph_get_next_endpoint(dev_fwnode(fb->dev), NULL);
> +	if (!endpoint)
> +		return -EINVAL;
> +
> +	v4l2_async_nf_init(&fb->notifier, &fb->v4l2_dev);
> +
> +	asc = v4l2_async_nf_add_fwnode_remote(&fb->notifier, endpoint,
> +					      struct v4l2_async_connection);
> +	fwnode_handle_put(endpoint);
> +
> +	if (IS_ERR(asc))
> +		return PTR_ERR(asc);
> +
> +	fb->notifier.ops = &chv3_fb_async_notify_ops;
> +	res = v4l2_async_nf_register(&fb->notifier);
> +	if (res) {
> +		v4l2_async_nf_cleanup(&fb->notifier);
> +		return res;
> +	}
> +
> +	return 0;
> +}
> +
> +static int chv3_fb_probe(struct platform_device *pdev)
> +{
> +	struct chv3_fb *fb;
> +	bool legacy_format;
> +	int res;
> +	int irq;
> +
> +	fb = devm_kzalloc(&pdev->dev, sizeof(*fb), GFP_KERNEL);
> +	if (!fb)
> +		return -ENOMEM;
> +	fb->dev = &pdev->dev;
> +	platform_set_drvdata(pdev, fb);
> +
> +	/* map register space */
> +	fb->iobase = devm_platform_ioremap_resource(pdev, 0);
> +	if (IS_ERR(fb->iobase))
> +		return PTR_ERR(fb->iobase);
> +
> +	fb->iobase_irq = devm_platform_ioremap_resource(pdev, 1);
> +	if (IS_ERR(fb->iobase_irq))
> +		return PTR_ERR(fb->iobase_irq);
> +
> +	/* check hw version */
> +	res = chv3_fb_check_version(fb);
> +	if (res)
> +		return res;
> +
> +	/* setup interrupts */
> +	irq = platform_get_irq(pdev, 0);
> +	if (irq < 0)
> +		return -ENXIO;
> +	res = devm_request_irq(&pdev->dev, irq, chv3_fb_isr, 0, DEVICE_NAME, fb);
> +	if (res)
> +		return res;
> +
> +	/* initialize v4l2_device */
> +	res = v4l2_device_register(&pdev->dev, &fb->v4l2_dev);
> +	if (res)
> +		return res;
> +
> +	/* initialize vb2 queue */
> +	fb->queue.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
> +	fb->queue.io_modes = VB2_MMAP | VB2_DMABUF;
> +	fb->queue.dev = &pdev->dev;
> +	fb->queue.lock = &fb->fb_lock;
> +	fb->queue.ops = &chv3_fb_vb2_ops;
> +	fb->queue.mem_ops = &vb2_dma_contig_memops;
> +	fb->queue.drv_priv = fb;
> +	fb->queue.buf_struct_size = sizeof(struct chv3_fb_buffer);
> +	fb->queue.timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC;
> +	res = vb2_queue_init(&fb->queue);
> +	if (res)
> +		goto error;
> +
> +	/* initialize video_device */
> +	strscpy(fb->vdev.name, DEVICE_NAME, sizeof(fb->vdev.name));
> +	fb->vdev.fops = &chv3_fb_v4l2_fops;
> +	fb->vdev.ioctl_ops = &chv3_fb_v4l2_ioctl_ops;
> +	fb->vdev.lock = &fb->fb_lock;
> +	fb->vdev.release = video_device_release_empty;
> +	fb->vdev.device_caps = V4L2_CAP_VIDEO_CAPTURE | V4L2_CAP_STREAMING;
> +	fb->vdev.v4l2_dev = &fb->v4l2_dev;
> +	fb->vdev.queue = &fb->queue;
> +	video_set_drvdata(&fb->vdev, fb);
> +
> +	/* read other DT properties */
> +	legacy_format = device_property_read_bool(&pdev->dev, "google,legacy-format");
> +
> +	if (device_get_named_child_node(&pdev->dev, "port"))
> +		res = chv3_fb_fwnode_init(fb);
> +	else
> +		res = chv3_fb_fallback_init(fb);
> +	if (res)
> +		goto error;
> +
> +	/* initialize rest of driver struct */
> +	INIT_LIST_HEAD(&fb->bufs);
> +	spin_lock_init(&fb->bufs_lock);
> +	mutex_init(&fb->fb_lock);
> +
> +	chv3_fb_set_default_format(fb, legacy_format);
> +	chv3_fb_set_default_timings(fb);
> +
> +	/* initialize hw */
> +	writel(FB_RESET_BIT, fb->iobase + FB_RESET);
> +	writel(FB_DATARATE_DOUBLE, fb->iobase + FB_DATARATE);
> +	writel(FB_PIXELMODE_DOUBLE, fb->iobase + FB_PIXELMODE);
> +	if (legacy_format)
> +		writel(FB_DMAFORMAT_8BPC_LEGACY, fb->iobase + FB_DMAFORMAT);
> +	else
> +		writel(FB_DMAFORMAT_8BPC, fb->iobase + FB_DMAFORMAT);
> +
> +	writel(FB_IRQ_ALL, fb->iobase_irq + FB_IRQ_MASK);
> +
> +	return 0;
> +
> +error:
> +	v4l2_device_unregister(&fb->v4l2_dev);
> +
> +	return res;
> +}
> +
> +static void chv3_fb_remove(struct platform_device *pdev)
> +{
> +	struct chv3_fb *fb = platform_get_drvdata(pdev);
> +
> +	/* disable interrupts */
> +	writel(0, fb->iobase_irq + FB_IRQ_MASK);
> +
> +	v4l2_async_nf_unregister(&fb->notifier);
> +	v4l2_async_nf_cleanup(&fb->notifier);
> +	v4l2_device_unregister(&fb->v4l2_dev);
> +}
> +
> +static const struct of_device_id chv3_fb_match_table[] = {
> +	{ .compatible = "google,chv3-fb" },
> +	{ },
> +};
> +
> +static struct platform_driver chv3_fb_platform_driver = {
> +	.probe = chv3_fb_probe,
> +	.remove_new = chv3_fb_remove,
> +	.driver = {
> +		.name = DEVICE_NAME,
> +		.of_match_table = chv3_fb_match_table,
> +	},
> +};
> +
> +module_platform_driver(chv3_fb_platform_driver);
> +
> +MODULE_AUTHOR("Paweł Anikiel <panikiel@google.com>");
> +MODULE_DESCRIPTION("Google Chameleon v3 video framebuffer driver");
> +MODULE_LICENSE("GPL");

For the v3, can you also provide the output of 'v4l2-compliance -s'
in the cover letter? Make sure you compile v4l2-compliance directly
from the git repo https://git.linuxtv.org/v4l-utils.git/ since the version
from distros is usually too old.

Regards,

	Hans