Hi Helen,
On Fri, Jul 3, 2020 at 10:00 PM Helen Koike <helen.koike@xxxxxxxxxxxxx> 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@xxxxxxxxxxxxx>
> > ---
> > 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.
>
> 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.
That's my interpretation of the spec and I would choose to implement
such behavior, however not everyone agrees on that. Please check the
discussion over the v3 series [1].
[1] https://lore.kernel.org/linux-media/20200702184324.GP12562@xxxxxxxxxxxxxxxxxxxxxxxxxx/
Best regards,
Tomasz
