[PATCH v5 6/7] media: staging: rkisp1: allow quantization setting by userspace on the isp source pad
Tomasz Figa
tfiga at chromium.org
Wed Jul 22 13:20:54 EDT 2020
On Wed, Jul 22, 2020 at 7:13 PM Helen Koike <helen.koike at collabora.com> wrote:
>
> Hi,
>
> On 7/22/20 10:12 AM, Tomasz Figa wrote:
> > On Fri, Jul 03, 2020 at 05:00:40PM -0300, Helen Koike wrote:
> >> Hi Dafna,
> >>
> >> Thanks for your patch.
> >>
> >> On 7/3/20 2:10 PM, Dafna Hirschfeld wrote:
> >>> The isp entity has a hardware support to force full range quantization
> >>> for YUV formats. Use the subdev CSC API to allow userspace to set the
> >>> quantization for YUV formats on the isp entity.
> >>>
> >>> - The flag V4L2_SUBDEV_MBUS_CODE_CSC_QUANTIZATION is set on
> >>> YUV formats during enumeration of the isp formats on the source pad.
> >>> - The full quantization is set on YUV formats if userspace ask it
> >>> on the isp entity using the flag V4L2_MBUS_FRAMEFMT_SET_CSC.
> >>>
> >>> On the capture and the resizer, the quantization is read-only
> >>> and always set to the default quantization.
> >>>
> >>> Signed-off-by: Dafna Hirschfeld <dafna.hirschfeld at collabora.com>
> >>> ---
> >>> drivers/staging/media/rkisp1/TODO | 2 +-
> >>> drivers/staging/media/rkisp1/rkisp1-capture.c | 10 ----------
> >>> drivers/staging/media/rkisp1/rkisp1-isp.c | 18 ++++++++++++++----
> >>> 3 files changed, 15 insertions(+), 15 deletions(-)
> >>>
> >>> diff --git a/drivers/staging/media/rkisp1/TODO b/drivers/staging/media/rkisp1/TODO
> >>> index c0cbec0a164d..db05288949bd 100644
> >>> --- a/drivers/staging/media/rkisp1/TODO
> >>> +++ b/drivers/staging/media/rkisp1/TODO
> >>> @@ -2,7 +2,7 @@
> >>> * Use threaded interrupt for rkisp1_stats_isr(), remove work queue.
> >>> * Fix checkpatch errors.
> >>> * Review and comment every lock
> >>> -* Handle quantization
> >>> +* Add uapi docs. Remeber to add documentation of how quantization is handled.
> >>> * Document rkisp1-common.h
> >>> * streaming paths (mainpath and selfpath) check if the other path is streaming
> >>> in several places of the code, review this, specially that it doesn't seem it
> >>> diff --git a/drivers/staging/media/rkisp1/rkisp1-capture.c b/drivers/staging/media/rkisp1/rkisp1-capture.c
> >>> index f69235f82c45..93d6846886f2 100644
> >>> --- a/drivers/staging/media/rkisp1/rkisp1-capture.c
> >>> +++ b/drivers/staging/media/rkisp1/rkisp1-capture.c
> >>> @@ -1085,8 +1085,6 @@ static void rkisp1_try_fmt(const struct rkisp1_capture *cap,
> >>> const struct v4l2_format_info **fmt_info)
> >>> {
> >>> const struct rkisp1_capture_config *config = cap->config;
> >>> - struct rkisp1_capture *other_cap =
> >>> - &cap->rkisp1->capture_devs[cap->id ^ 1];
> >>> const struct rkisp1_capture_fmt_cfg *fmt;
> >>> const struct v4l2_format_info *info;
> >>> const unsigned int max_widths[] = { RKISP1_RSZ_MP_SRC_MAX_WIDTH,
> >>> @@ -1111,14 +1109,6 @@ static void rkisp1_try_fmt(const struct rkisp1_capture *cap,
> >>>
> >>> info = rkisp1_fill_pixfmt(pixm, cap->id);
> >>>
> >>> - /* can not change quantization when stream-on */
> >>> - if (other_cap->is_streaming)
> >>> - pixm->quantization = other_cap->pix.fmt.quantization;
> >>> - /* output full range by default, take effect in params */
> >>> - else if (!pixm->quantization ||
> >>> - pixm->quantization > V4L2_QUANTIZATION_LIM_RANGE)
> >>> - pixm->quantization = V4L2_QUANTIZATION_FULL_RANGE;
> >>> -
> >>> if (fmt_cfg)
> >>> *fmt_cfg = fmt;
> >>> if (fmt_info)
> >>> diff --git a/drivers/staging/media/rkisp1/rkisp1-isp.c b/drivers/staging/media/rkisp1/rkisp1-isp.c
> >>> index 58c90c67594d..d575c1e4dc4b 100644
> >>> --- a/drivers/staging/media/rkisp1/rkisp1-isp.c
> >>> +++ b/drivers/staging/media/rkisp1/rkisp1-isp.c
> >>> @@ -589,6 +589,10 @@ static int rkisp1_isp_enum_mbus_code(struct v4l2_subdev *sd,
> >>>
> >>> if (code->index == pos - 1) {
> >>> code->code = fmt->mbus_code;
> >>> + if (fmt->pixel_enc == V4L2_PIXEL_ENC_YUV &&
> >>> + dir == RKISP1_ISP_SD_SRC)
> >>> + code->flags =
> >>> + V4L2_SUBDEV_MBUS_CODE_CSC_QUANTIZATION;
> >>> return 0;
> >>> }
> >>> }
> >>> @@ -620,7 +624,6 @@ static int rkisp1_isp_init_config(struct v4l2_subdev *sd,
> >>> RKISP1_ISP_PAD_SOURCE_VIDEO);
> >>> *src_fmt = *sink_fmt;
> >>> src_fmt->code = RKISP1_DEF_SRC_PAD_FMT;
> >>> - src_fmt->quantization = V4L2_QUANTIZATION_FULL_RANGE;
> >>>
> >>> src_crop = v4l2_subdev_get_try_crop(sd, cfg,
> >>> RKISP1_ISP_PAD_SOURCE_VIDEO);
> >>> @@ -663,10 +666,17 @@ static void rkisp1_isp_set_src_fmt(struct rkisp1_isp *isp,
> >>> isp->src_fmt = mbus_info;
> >>> src_fmt->width = src_crop->width;
> >>> src_fmt->height = src_crop->height;
> >>> - src_fmt->quantization = format->quantization;
> >>> - /* full range by default */
> >>> - if (!src_fmt->quantization)
> >>> +
> >>> + /*
> >>> + * The CSC API is used to allow userspace to force full
> >>> + * quantization on YUV formats.
> >>> + */
> >>> + if (format->flags & V4L2_MBUS_FRAMEFMT_SET_CSC &&
> >>> + format->quantization == V4L2_QUANTIZATION_FULL_RANGE &&
> >>> + mbus_info->pixel_enc == V4L2_PIXEL_ENC_YUV)
> >>> src_fmt->quantization = V4L2_QUANTIZATION_FULL_RANGE;
> >>> + else
> >>> + src_fmt->quantization = V4L2_QUANTIZATION_DEFAULT;
> >>
> >> According to the docs [1]:
> >>
> >> [1] https://linuxtv.org/downloads/v4l-dvb-apis-new/userspace-api/v4l/colorspaces-defs.html?highlight=quantization
> >>
> >> "The default colorspace. This can be used by applications to let the driver fill in the colorspace."
> >>
> >> So, in my understanding, the driver should never return V4L2_QUANTIZATION_DEFAULT to userspace.
> >>
> >
> > The part of the documentation you quoted comes from the description of
> > V4L2_COLORSPACE_DEFAULT and not V4L2_QUANTIZATION_DEFAULT.
> >
> > For the latter it says:
> >
> > "Use the default quantization encoding as defined by the colorspace.
> > This is always full range for R’G’B’ (except for the BT.2020 colorspace)
> > and HSV. It is usually limited range for Y’CbCr."
> >
> > Which, in my understanding, doesn't suggest in any way that it shouldn't
> > be returned by the driver. There is also a valid case when the driver
> > simply doesn't know or care what quantization the captured signal uses.
>
> Thanks for this clarification.
>
> >
> > However, in this case, I don't see why we would return DEFAULT here
> > indeed, as the driver has the full knowledge, RGB is full range and YUV
> > is limited range unless full range was requested.
> >
> >> We have the same issue in the resizer.
> >>
> >> I also see an issue in the capture that allows userspace to change quantization, and this should be fixed.
> >>
> >> In my understanding, since you are leaving all the other pads and video nodes with read-only quantization,
> >> changing quantization in the ISP source pad should change the readings in all the other pads and video nodes.
> >> So, if all pads are reporting V4L2_QUANTIZATION_LIM_RANGE (which is the default for sRGB colorspace), and userspace sets
> >> V4L2_QUANTIZATION_FULL_RANGE to the isp source pad, then all the other pads and video nodes should also report
> >> V4L2_QUANTIZATION_FULL_RANGE, since this will be the actual quantization used by the driver.
> >
> > This was extensively discussed at v3:
> > https://patchwork.kernel.org/patch/11493105/
> >
> > The conclusion is that there is no value from both the kernel and the userspace point of
> > view in propagating this to the end of the pipeline, because the
> > hardware components later in the pipeline don't care and the userspace,
> > given the DEFAULT quantization value, can infer the exact quantziation from the
> > pipeline - here from what it configured at the ISP entity.
>
> Let's use DEFAULT then, sounds the simplest solution imho, unless you disagree.
>
> Acked-by: Helen Koike <helen.koike at collabora.com>
Yes. Laurent convinced me that it is indeed the right behavior here.
Reviewed-by: Tomasz Figa <tfiga at chromium.org>
Best regards,
Tomasz
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