On 08/12/2020 00:51, Laurent Pinchart wrote:
> Hi Hans,
>
> On Mon, Dec 07, 2020 at 11:11:33AM +0100, Hans Verkuil wrote:
>> On 07/12/2020 00:53, Laurent Pinchart wrote:
>>> The CAL driver is video node centric, it controls the whole device
>>> through the video device nodes. This limits the possible use cases as it
>>> can't support sources that are more complex than a single subdev. To
>>> support more complex hardware pipelines, implement support for the media
>>> controller centric API. The exposed API can be selected through a module
>>> parameter.
>>>
>>> Signed-off-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
>>> ---
>>> Changes since v1:
>>>
>>> - Fix parameter name and description in MODULE_PARM_DESC()
>>> ---
>>> drivers/media/platform/ti-vpe/cal-camerarx.c | 1 +
>>> drivers/media/platform/ti-vpe/cal-video.c | 356 ++++++++++++++-----
>>> drivers/media/platform/ti-vpe/cal.c | 10 +-
>>> drivers/media/platform/ti-vpe/cal.h | 2 +
>>> 4 files changed, 288 insertions(+), 81 deletions(-)
>>>
>>> diff --git a/drivers/media/platform/ti-vpe/cal-camerarx.c b/drivers/media/platform/ti-vpe/cal-camerarx.c
>>> index 1920f36137b8..8abf887c47d6 100644
>>> --- a/drivers/media/platform/ti-vpe/cal-camerarx.c
>>> +++ b/drivers/media/platform/ti-vpe/cal-camerarx.c
>>> @@ -830,6 +830,7 @@ struct cal_camerarx *cal_camerarx_create(struct cal_dev *cal,
>>> sd = &phy->subdev;
>>> v4l2_subdev_init(sd, &cal_camerarx_subdev_ops);
>>> sd->entity.function = MEDIA_ENT_F_VID_IF_BRIDGE;
>>> + sd->flags = V4L2_SUBDEV_FL_HAS_DEVNODE;
>>> snprintf(sd->name, sizeof(sd->name), "CAMERARX%u", instance);
>>> sd->dev = cal->dev;
>>>
>>> diff --git a/drivers/media/platform/ti-vpe/cal-video.c b/drivers/media/platform/ti-vpe/cal-video.c
>>> index 779f1e1bc529..119a17fb97bc 100644
>>> --- a/drivers/media/platform/ti-vpe/cal-video.c
>>> +++ b/drivers/media/platform/ti-vpe/cal-video.c
>>> @@ -40,40 +40,10 @@ static char *fourcc_to_str(u32 fmt)
>>> }
>>>
>>> /* ------------------------------------------------------------------
>>> - * V4L2 Video IOCTLs
>>> + * V4L2 Common IOCTLs
>>> * ------------------------------------------------------------------
>>> */
>>>
>>> -static const struct cal_format_info *find_format_by_pix(struct cal_ctx *ctx,
>>> - u32 pixelformat)
>>> -{
>>> - const struct cal_format_info *fmtinfo;
>>> - unsigned int k;
>>> -
>>> - for (k = 0; k < ctx->num_active_fmt; k++) {
>>> - fmtinfo = ctx->active_fmt[k];
>>> - if (fmtinfo->fourcc == pixelformat)
>>> - return fmtinfo;
>>> - }
>>> -
>>> - return NULL;
>>> -}
>>> -
>>> -static const struct cal_format_info *find_format_by_code(struct cal_ctx *ctx,
>>> - u32 code)
>>> -{
>>> - const struct cal_format_info *fmtinfo;
>>> - unsigned int k;
>>> -
>>> - for (k = 0; k < ctx->num_active_fmt; k++) {
>>> - fmtinfo = ctx->active_fmt[k];
>>> - if (fmtinfo->code == code)
>>> - return fmtinfo;
>>> - }
>>> -
>>> - return NULL;
>>> -}
>>> -
>>> static int cal_querycap(struct file *file, void *priv,
>>> struct v4l2_capability *cap)
>>> {
>>> @@ -87,6 +57,51 @@ static int cal_querycap(struct file *file, void *priv,
>>> return 0;
>>> }
>>>
>>> +static int cal_g_fmt_vid_cap(struct file *file, void *priv,
>>> + struct v4l2_format *f)
>>> +{
>>> + struct cal_ctx *ctx = video_drvdata(file);
>>> +
>>> + *f = ctx->v_fmt;
>>> +
>>> + return 0;
>>> +}
>>> +
>>> +/* ------------------------------------------------------------------
>>> + * V4L2 Video Node Centric IOCTLs
>>> + * ------------------------------------------------------------------
>>> + */
>>> +
>>> +static const struct cal_format_info *find_format_by_pix(struct cal_ctx *ctx,
>>> + u32 pixelformat)
>>> +{
>>> + const struct cal_format_info *fmtinfo;
>>> + unsigned int k;
>>> +
>>> + for (k = 0; k < ctx->num_active_fmt; k++) {
>>> + fmtinfo = ctx->active_fmt[k];
>>> + if (fmtinfo->fourcc == pixelformat)
>>> + return fmtinfo;
>>> + }
>>> +
>>> + return NULL;
>>> +}
>>> +
>>> +static const struct cal_format_info *find_format_by_code(struct cal_ctx *ctx,
>>> + u32 code)
>>> +{
>>> + const struct cal_format_info *fmtinfo;
>>> + unsigned int k;
>>> +
>>> + for (k = 0; k < ctx->num_active_fmt; k++) {
>>> + fmtinfo = ctx->active_fmt[k];
>>> + if (fmtinfo->code == code)
>>> + return fmtinfo;
>>> + }
>>> +
>>> + return NULL;
>>> +}
>>> +
>>> static int cal_enum_fmt_vid_cap(struct file *file, void *priv,
>>> struct v4l2_fmtdesc *f)
>>> {
>>> @@ -174,16 +189,6 @@ static void cal_calc_format_size(struct cal_ctx *ctx,
>>> f->fmt.pix.bytesperline, f->fmt.pix.sizeimage);
>>> }
>>>
>>> -static int cal_g_fmt_vid_cap(struct file *file, void *priv,
>>> - struct v4l2_format *f)
>>> -{
>>> - struct cal_ctx *ctx = video_drvdata(file);
>>> -
>>> - *f = ctx->v_fmt;
>>> -
>>> - return 0;
>>> -}
>>> -
>>> static int cal_try_fmt_vid_cap(struct file *file, void *priv,
>>> struct v4l2_format *f)
>>> {
>>> @@ -383,16 +388,7 @@ static int cal_enum_frameintervals(struct file *file, void *priv,
>>> return 0;
>>> }
>>>
>>> -static const struct v4l2_file_operations cal_fops = {
>>> - .owner = THIS_MODULE,
>>> - .open = v4l2_fh_open,
>>> - .release = vb2_fop_release,
>>> - .poll = vb2_fop_poll,
>>> - .unlocked_ioctl = video_ioctl2, /* V4L2 ioctl handler */
>>> - .mmap = vb2_fop_mmap,
>>> -};
>>> -
>>> -static const struct v4l2_ioctl_ops cal_ioctl_ops = {
>>> +static const struct v4l2_ioctl_ops cal_ioctl_video_ops = {
>>> .vidioc_querycap = cal_querycap,
>>> .vidioc_enum_fmt_vid_cap = cal_enum_fmt_vid_cap,
>>> .vidioc_g_fmt_vid_cap = cal_g_fmt_vid_cap,
>>> @@ -418,7 +414,153 @@ static const struct v4l2_ioctl_ops cal_ioctl_ops = {
>>> };
>>>
>>> /* ------------------------------------------------------------------
>>> - * videobuf2 Operations
>>> + * V4L2 Media Controller Centric IOCTLs
>>> + * ------------------------------------------------------------------
>>> + */
>>> +
>>> +static int cal_mc_enum_fmt_vid_cap(struct file *file, void *priv,
>>> + struct v4l2_fmtdesc *f)
>>> +{
>>> + if (f->index >= cal_num_formats)
>>> + return -EINVAL;
>>> +
>>> + f->pixelformat = cal_formats[f->index].fourcc;
>>> + f->type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
>>> +
>>> + return 0;
>>> +}
>>> +
>>> +static void cal_mc_try_fmt(struct cal_ctx *ctx, struct v4l2_format *f,
>>> + const struct cal_format_info **info)
>>> +{
>>> + struct v4l2_pix_format *format = &f->fmt.pix;
>>> + const struct cal_format_info *fmtinfo;
>>> + unsigned int bpp;
>>> +
>>> + /*
>>> + * Default to the first format is the requested pixel format code isn't
>>> + * supported.
>>> + */
>>> + fmtinfo = cal_format_by_fourcc(f->fmt.pix.pixelformat);
>>> + if (!fmtinfo)
>>> + fmtinfo = &cal_formats[0];
>>> +
>>> + /*
>>> + * Clamp the size, update the pixel format. The field and colorspace are
>>> + * accepted as-is, except for V4L2_FIELD_ANY that is turned into
>>> + * V4L2_FIELD_NONE.
>>> + */
>>> + bpp = ALIGN(fmtinfo->bpp, 8);
>>> +
>>> + format->width = clamp_t(unsigned int, format->width,
>>> + CAL_MIN_WIDTH_BYTES * 8 / bpp,
>>> + CAL_MAX_WIDTH_BYTES * 8 / bpp);
>>> + format->height = clamp_t(unsigned int, format->height,
>>> + CAL_MIN_HEIGHT_LINES, CAL_MAX_HEIGHT_LINES);
>>> + format->pixelformat = fmtinfo->fourcc;
>>> +
>>> + if (format->field == V4L2_FIELD_ANY)
>>> + format->field = V4L2_FIELD_NONE;
>>> +
>>> + /*
>>> + * Calculate the number of bytes per line and the image size. The
>>> + * hardware stores the stride as a number of 16 bytes words, in a
>>> + * signed 15-bit value. Only 14 bits are thus usable.
>>> + */
>>> + format->bytesperline = ALIGN(clamp(format->bytesperline,
>>> + format->width * bpp / 8,
>>> + ((1U << 14) - 1) * 16), 16);
>>> +
>>> + format->sizeimage = format->height * format->bytesperline;
>>> +
>>> + if (info)
>>> + *info = fmtinfo;
>>> +
>>> + ctx_dbg(3, ctx, "%s: %s %ux%u (bytesperline %u sizeimage %u)\n",
>>> + __func__, fourcc_to_str(format->pixelformat),
>>> + format->width, format->height,
>>> + format->bytesperline, format->sizeimage);
>>> +}
>>> +
>>> +static int cal_mc_try_fmt_vid_cap(struct file *file, void *priv,
>>> + struct v4l2_format *f)
>>> +{
>>> + struct cal_ctx *ctx = video_drvdata(file);
>>> +
>>> + cal_mc_try_fmt(ctx, f, NULL);
>>> + return 0;
>>> +}
>>> +
>>> +static int cal_mc_s_fmt_vid_cap(struct file *file, void *priv,
>>> + struct v4l2_format *f)
>>> +{
>>> + struct cal_ctx *ctx = video_drvdata(file);
>>> + const struct cal_format_info *fmtinfo;
>>> +
>>> + if (vb2_is_busy(&ctx->vb_vidq)) {
>>> + ctx_dbg(3, ctx, "%s device busy\n", __func__);
>>> + return -EBUSY;
>>> + }
>>> +
>>> + cal_mc_try_fmt(ctx, f, &fmtinfo);
>>> +
>>> + ctx->v_fmt = *f;
>>> + ctx->fmtinfo = fmtinfo;
>>> +
>>> + return 0;
>>> +}
>>> +
>>> +static int cal_mc_enum_framesizes(struct file *file, void *fh,
>>> + struct v4l2_frmsizeenum *fsize)
>>> +{
>>> + struct cal_ctx *ctx = video_drvdata(file);
>>> + const struct cal_format_info *fmtinfo;
>>> + unsigned int bpp;
>>> +
>>> + if (fsize->index > 0)
>>> + return -EINVAL;
>>> +
>>> + fmtinfo = cal_format_by_fourcc(fsize->pixel_format);
>>> + if (!fmtinfo) {
>>> + ctx_dbg(3, ctx, "Invalid pixel format 0x%08x\n",
>>> + fsize->pixel_format);
>>> + return -EINVAL;
>>> + }
>>> +
>>> + bpp = ALIGN(fmtinfo->bpp, 8);
>>> +
>>> + fsize->type = V4L2_FRMSIZE_TYPE_STEPWISE;
>>> + fsize->stepwise.min_width = CAL_MIN_WIDTH_BYTES * 8 / bpp;
>>> + fsize->stepwise.max_width = CAL_MAX_WIDTH_BYTES * 8 / bpp;
>>> + fsize->stepwise.step_width = 64 / bpp;
>>> + fsize->stepwise.min_height = CAL_MIN_HEIGHT_LINES;
>>> + fsize->stepwise.max_height = CAL_MAX_HEIGHT_LINES;
>>> + fsize->stepwise.step_height = 1;
>>> +
>>> + return 0;
>>> +}
>>> +
>>> +static const struct v4l2_ioctl_ops cal_ioctl_mc_ops = {
>>> + .vidioc_querycap = cal_querycap,
>>> + .vidioc_enum_fmt_vid_cap = cal_mc_enum_fmt_vid_cap,
>>> + .vidioc_g_fmt_vid_cap = cal_g_fmt_vid_cap,
>>> + .vidioc_try_fmt_vid_cap = cal_mc_try_fmt_vid_cap,
>>> + .vidioc_s_fmt_vid_cap = cal_mc_s_fmt_vid_cap,
>>> + .vidioc_enum_framesizes = cal_mc_enum_framesizes,
>>> + .vidioc_reqbufs = vb2_ioctl_reqbufs,
>>> + .vidioc_create_bufs = vb2_ioctl_create_bufs,
>>> + .vidioc_prepare_buf = vb2_ioctl_prepare_buf,
>>> + .vidioc_querybuf = vb2_ioctl_querybuf,
>>> + .vidioc_qbuf = vb2_ioctl_qbuf,
>>> + .vidioc_dqbuf = vb2_ioctl_dqbuf,
>>> + .vidioc_expbuf = vb2_ioctl_expbuf,
>>> + .vidioc_streamon = vb2_ioctl_streamon,
>>> + .vidioc_streamoff = vb2_ioctl_streamoff,
>>> + .vidioc_log_status = v4l2_ctrl_log_status,
>>> +};
>>> +
>>> +/* ------------------------------------------------------------------
>>> + * videobuf2 Common Operations
>>> * ------------------------------------------------------------------
>>> */
>>>
>>> @@ -504,6 +646,26 @@ static void cal_release_buffers(struct cal_ctx *ctx,
>>> spin_unlock_irq(&ctx->dma.lock);
>>> }
>>>
>>> +/* ------------------------------------------------------------------
>>> + * videobuf2 Operations
>>> + * ------------------------------------------------------------------
>>> + */
>>> +
>>> +static int cal_video_check_format(struct cal_ctx *ctx)
>>> +{
>>> + const struct v4l2_mbus_framefmt *format;
>>> +
>>> + format = &ctx->phy->formats[CAL_CAMERARX_PAD_SOURCE];
>>> +
>>> + if (ctx->fmtinfo->code != format->code ||
>>> + ctx->v_fmt.fmt.pix.height != format->height ||
>>> + ctx->v_fmt.fmt.pix.width != format->width ||
>>> + ctx->v_fmt.fmt.pix.field != format->field)
>>> + return -EPIPE;
>>> +
>>> + return 0;
>>> +}
>>> +
>>> static int cal_start_streaming(struct vb2_queue *vq, unsigned int count)
>>> {
>>> struct cal_ctx *ctx = vb2_get_drv_priv(vq);
>>> @@ -511,6 +673,23 @@ static int cal_start_streaming(struct vb2_queue *vq, unsigned int count)
>>> dma_addr_t addr;
>>> int ret;
>>>
>>> + ret = media_pipeline_start(&ctx->vdev.entity, &ctx->phy->pipe);
>>> + if (ret < 0) {
>>> + ctx_err(ctx, "Failed to start media pipeline: %d\n", ret);
>>> + return ret;
>>> + }
>>> +
>>> + /*
>>> + * Verify that the currently configured format matches the output of
>>> + * the connected CAMERARX.
>>> + */
>>> + ret = cal_video_check_format(ctx);
>>> + if (ret < 0) {
>>> + ctx_dbg(3, ctx,
>>> + "Format mismatch between CAMERARX and video node\n");
>>> + goto error_pipeline;
>>> + }
>>> +
>>> spin_lock_irq(&ctx->dma.lock);
>>> buf = list_first_entry(&ctx->dma.queue, struct cal_buffer, list);
>>> ctx->dma.pending = buf;
>>> @@ -526,18 +705,21 @@ static int cal_start_streaming(struct vb2_queue *vq, unsigned int count)
>>>
>>> ret = v4l2_subdev_call(&ctx->phy->subdev, video, s_stream, 1);
>>> if (ret)
>>> - goto err;
>>> + goto error_stop;
>>>
>>> if (cal_debug >= 4)
>>> cal_quickdump_regs(ctx->cal);
>>>
>>> return 0;
>>>
>>> -err:
>>> +error_stop:
>>> cal_ctx_stop(ctx);
>>> pm_runtime_put_sync(ctx->cal->dev);
>>>
>>> +error_pipeline:
>>> + media_pipeline_stop(&ctx->vdev.entity);
>>> cal_release_buffers(ctx, VB2_BUF_STATE_QUEUED);
>>> +
>>> return ret;
>>> }
>>>
>>> @@ -552,6 +734,8 @@ static void cal_stop_streaming(struct vb2_queue *vq)
>>> pm_runtime_put_sync(ctx->cal->dev);
>>>
>>> cal_release_buffers(ctx, VB2_BUF_STATE_ERROR);
>>> +
>>> + media_pipeline_stop(&ctx->vdev.entity);
>>> }
>>>
>>> static const struct vb2_ops cal_video_qops = {
>>> @@ -569,13 +753,13 @@ static const struct vb2_ops cal_video_qops = {
>>> * ------------------------------------------------------------------
>>> */
>>>
>>> -static const struct video_device cal_videodev = {
>>> - .name = CAL_MODULE_NAME,
>>> - .fops = &cal_fops,
>>> - .ioctl_ops = &cal_ioctl_ops,
>>> - .minor = -1,
>>> - .release = video_device_release_empty,
>>> - .device_caps = V4L2_CAP_VIDEO_CAPTURE | V4L2_CAP_STREAMING,
>>> +static const struct v4l2_file_operations cal_fops = {
>>> + .owner = THIS_MODULE,
>>> + .open = v4l2_fh_open,
>>> + .release = vb2_fop_release,
>>> + .poll = vb2_fop_poll,
>>> + .unlocked_ioctl = video_ioctl2, /* V4L2 ioctl handler */
>>> + .mmap = vb2_fop_mmap,
>>> };
>>>
>>> static int cal_ctx_v4l2_init_formats(struct cal_ctx *ctx)
>>> @@ -649,19 +833,22 @@ static int cal_ctx_v4l2_init_formats(struct cal_ctx *ctx)
>>>
>>> int cal_ctx_v4l2_register(struct cal_ctx *ctx)
>>> {
>>> - struct v4l2_ctrl_handler *hdl = &ctx->ctrl_handler;
>>> struct video_device *vfd = &ctx->vdev;
>>> int ret;
>>>
>>> - ret = cal_ctx_v4l2_init_formats(ctx);
>>> - if (ret)
>>> - return ret;
>>> + if (!cal_mc_api) {
>>> + struct v4l2_ctrl_handler *hdl = &ctx->ctrl_handler;
>>>
>>> - ret = v4l2_ctrl_add_handler(hdl, ctx->phy->sensor->ctrl_handler, NULL,
>>> - true);
>>> - if (ret < 0) {
>>> - ctx_err(ctx, "Failed to add sensor ctrl handler\n");
>>> - return ret;
>>> + ret = cal_ctx_v4l2_init_formats(ctx);
>>> + if (ret)
>>> + return ret;
>>> +
>>> + ret = v4l2_ctrl_add_handler(hdl, ctx->phy->sensor->ctrl_handler,
>>> + NULL, true);
>>> + if (ret < 0) {
>>> + ctx_err(ctx, "Failed to add sensor ctrl handler\n");
>>> + return ret;
>>> + }
>>> }
>>>
>>> ret = video_register_device(vfd, VFL_TYPE_VIDEO, cal_video_nr);
>>> @@ -698,7 +885,6 @@ void cal_ctx_v4l2_unregister(struct cal_ctx *ctx)
>>>
>>> int cal_ctx_v4l2_init(struct cal_ctx *ctx)
>>> {
>>> - struct v4l2_ctrl_handler *hdl = &ctx->ctrl_handler;
>>> struct video_device *vfd = &ctx->vdev;
>>> struct vb2_queue *q = &ctx->vb_vidq;
>>> int ret;
>>> @@ -725,10 +911,14 @@ int cal_ctx_v4l2_init(struct cal_ctx *ctx)
>>> return ret;
>>>
>>> /* Initialize the video device and media entity. */
>>> - *vfd = cal_videodev;
>>> + vfd->fops = &cal_fops;
>>> + vfd->device_caps = V4L2_CAP_VIDEO_CAPTURE | V4L2_CAP_STREAMING
>>> + | (cal_mc_api ? V4L2_CAP_IO_MC : 0);
>>> vfd->v4l2_dev = &ctx->cal->v4l2_dev;
>>> vfd->queue = q;
>>> snprintf(vfd->name, sizeof(vfd->name), "CAL output %u", ctx->index);
>>> + vfd->release = video_device_release_empty;
>>> + vfd->ioctl_ops = cal_mc_api ? &cal_ioctl_mc_ops : &cal_ioctl_video_ops;
>>> vfd->lock = &ctx->mutex;
>>> video_set_drvdata(vfd, ctx);
>>>
>>> @@ -737,15 +927,19 @@ int cal_ctx_v4l2_init(struct cal_ctx *ctx)
>>> if (ret < 0)
>>> return ret;
>>>
>>> - /* Initialize the control handler. */
>>> - ret = v4l2_ctrl_handler_init(hdl, 11);
>>> - if (ret < 0) {
>>> - ctx_err(ctx, "Failed to init ctrl handler\n");
>>> - goto error;
>>> + if (!cal_mc_api) {
>>> + /* Initialize the control handler. */
>>> + struct v4l2_ctrl_handler *hdl = &ctx->ctrl_handler;
>>> +
>>> + ret = v4l2_ctrl_handler_init(hdl, 11);
>>> + if (ret < 0) {
>>> + ctx_err(ctx, "Failed to init ctrl handler\n");
>>> + goto error;
>>> + }
>>> +
>>> + vfd->ctrl_handler = hdl;
>>> }
>>
>> I think it is a good idea if the probe() function will log whether this
>> driver is in MC or video centric mode.
>
> Would a debug message be fine ? I usually try to make the probe function
> silent by default to avoid adding to the already large boot time log.
I now realized that you set V4L2_CAP_IO_MC in the MC case, and that's easy
to check with v4l2-ctl -D, so userspace does have an easy method to see
whether or not it is MC-centric. So just ignore my comment, the code is fine
as it is now.
>
>>>
>>> - vfd->ctrl_handler = hdl;
>>> -
>>> return 0;
>>>
>>> error:
>>> @@ -755,6 +949,8 @@ int cal_ctx_v4l2_init(struct cal_ctx *ctx)
>>>
>>> void cal_ctx_v4l2_cleanup(struct cal_ctx *ctx)
>>> {
>>> - v4l2_ctrl_handler_free(&ctx->ctrl_handler);
>>> + if (!cal_mc_api)
>>> + v4l2_ctrl_handler_free(&ctx->ctrl_handler);
>>> +
>>> media_entity_cleanup(&ctx->vdev.entity);
>>> }
>>> diff --git a/drivers/media/platform/ti-vpe/cal.c b/drivers/media/platform/ti-vpe/cal.c
>>> index 293cbac905b3..2ce2b6404c92 100644
>>> --- a/drivers/media/platform/ti-vpe/cal.c
>>> +++ b/drivers/media/platform/ti-vpe/cal.c
>>> @@ -43,6 +43,10 @@ unsigned int cal_debug;
>>> module_param_named(debug, cal_debug, uint, 0644);
>>> MODULE_PARM_DESC(debug, "activates debug info");
>>>
>>> +bool cal_mc_api;
>>> +module_param_named(mc_api, cal_mc_api, bool, 0444);
>>> +MODULE_PARM_DESC(mc_api, "activates the MC API");
>>> +
>>
>> I noticed that this defaults to video centric.
>>
>> To come back to the discussion of the v2 of this patch, I believe we
>> need to decide what to do here so we have a good template for future
>> drivers that need this.
>>
>> My opinion is that you want a Kconfig option to set the default for
>> this, so this becomes something like this:
>>
>> bool cal_mc_api = CONFIG_TI_CAL_MC_API;
>>
>> What do you think?
>>
>> I will make a PR for v5.12 for patches 1-23, but I would like to have this
>> remaining issue resolved before merging this final patch.
>>
>> I do think that a Kconfig option is very desirable, but whether the default
>> of this option should be y or n is less clear. Since this driver has always
>> been video-centric I can imagine that it makes sense to set it to n. But
>> for e.g. a new driver like the tegra-video driver (currently in staging),
>> it would make sense to set it to y since it is a new driver. Ditto for the
>> rpi camera driver.
>
> For this driver I think video-centric mode is the best default to start
> with, to avoid changing the behaviour all of a sudden. We can switch it
> to MC-centric by default later if desired, after userspace gets a chance
> to adapt.
Fair enough.
>
>> In that case the rule would be that for new mainline drivers the default
>> should always be y (MC-centric), but if the driver was already in mainline
>> and MC support is added (like for this driver), then the default remains n
>> for backwards compatibility.
>
> I think that for new drivers we shouldn't support video-centric mode at
> all. It should only be supported in downstream (vendor) kernels, and
> only if backward compatibility with existing userspace needs to be
> ensured. The unicam driver, for instance, fits in that category. Drivers
> whose development is ongoing (or hasn't started) should only use the MC
> API. Whether the option should be y or n by default would then be a
> vendor decision, it wouldn't affect upstream.
No, that I strongly disagree with. Vendors would have to carry those patches
for a long time, and if past experience is any guide, they will mess it up.
Or even refuse to upgrade to the mainline code because it is too much hassle
and instead keep using their own driver.
In my opinion the mainline driver should be MC-centric, and it is up to the
vendor to decide whether video-centric is also supported: this should only
be done if there is a long history of video-centric behavior in the past.
In that case a Kconfig option is needed to select MC, and in the mainline
kernel this should default to y for such new drivers.
In both Raspbian and Linux4Tegra video-centric has been the norm for many
years, so there are many userspace applications that expect that behavior.
You want those distros to use the mainline driver (eventually...) since
those distros are widely used so you also get a large installed base and
(hopefully) bug reports and bug fixes for the driver. If you decide to
require the distro to carry a patch to turn a driver into a video-centric
variant, then I am afraid they will not bother upgrading to the mainline
driver and just keep their own driver.
In any case, I really like your approach, all I want is a Kconfig option
and it is good to go.
Regards,
Hans
>
>>> /* ------------------------------------------------------------------
>>> * Format Handling
>>> * ------------------------------------------------------------------
>>> @@ -660,13 +664,17 @@ static int cal_async_notifier_complete(struct v4l2_async_notifier *notifier)
>>> {
>>> struct cal_dev *cal = container_of(notifier, struct cal_dev, notifier);
>>> unsigned int i;
>>> + int ret = 0;
>>>
>>> for (i = 0; i < ARRAY_SIZE(cal->ctx); ++i) {
>>> if (cal->ctx[i])
>>> cal_ctx_v4l2_register(cal->ctx[i]);
>>> }
>>>
>>> - return 0;
>>> + if (cal_mc_api)
>>> + ret = v4l2_device_register_subdev_nodes(&cal->v4l2_dev);
>>> +
>>> + return ret;
>>> }
>>>
>>> static const struct v4l2_async_notifier_operations cal_async_notifier_ops = {
>>> diff --git a/drivers/media/platform/ti-vpe/cal.h b/drivers/media/platform/ti-vpe/cal.h
>>> index 60f5f7480b17..199692610fb9 100644
>>> --- a/drivers/media/platform/ti-vpe/cal.h
>>> +++ b/drivers/media/platform/ti-vpe/cal.h
>>> @@ -160,6 +160,7 @@ struct cal_camerarx {
>>> struct device_node *sensor_ep_node;
>>> struct device_node *sensor_node;
>>> struct v4l2_subdev *sensor;
>>> + struct media_pipeline pipe;
>>>
>>> struct v4l2_subdev subdev;
>>> struct media_pad pads[2];
>>> @@ -224,6 +225,7 @@ struct cal_ctx {
>>>
>>> extern unsigned int cal_debug;
>>> extern int cal_video_nr;
>>> +extern bool cal_mc_api;
>>>
>>> #define cal_dbg(level, cal, fmt, arg...) \
>>> do { \
>
