Re: [PATCH v1 3/9] media: verisilicon: Save bit depth for AV1 decoder

Bonjour Nicolas,

On Mon, Dec 19, 2022 at 5:37 PM Nicolas Dufresne [off-list ref] wrote:

Le lundi 19 décembre 2022 à 16:56 +0100, Benjamin Gaignard a écrit :

quoted

Store bit depth information from AV1 sequence control.

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@collabora.com>
---
 .../media/platform/verisilicon/hantro_drv.c   | 26 +++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/drivers/media/platform/verisilicon/hantro_drv.c b/drivers/media/platform/verisilicon/hantro_drv.c
index 4500e1fc0f2c..8e93710dcfed 100644
--- a/drivers/media/platform/verisilicon/hantro_drv.c
+++ b/drivers/media/platform/verisilicon/hantro_drv.c

@@ -324,6 +324,25 @@ static int hantro_vp9_s_ctrl(struct v4l2_ctrl *ctrl)
      return 0;
 }

+static int hantro_av1_s_ctrl(struct v4l2_ctrl *ctrl)
+{
+     struct hantro_ctx *ctx;
+
+     ctx = container_of(ctrl->handler,
+                        struct hantro_ctx, ctrl_handler);
+
+     switch (ctrl->id) {
+     case V4L2_CID_STATELESS_AV1_SEQUENCE:
+             ctx->bit_depth = ctrl->p_new.p_av1_sequence->bit_depth;

That seems a little be weak, what happens if you change the bit_depth with a
non-request s_ctrl while its decoding ? To be this deserve a little bit of
protection, a something that validate and copy it at the start of the decoding.

Oh, nice catch. We need to return EBUSY, see
https://www.kernel.org/doc/html/v5.0/media/uapi/v4l/buffer.html#interactions-between-formats-controls-and-buffers.

There's already an API in the V4L2 control framework for drivers to use,
see v4l2_ctrl_grab in
https://www.kernel.org/doc/html/v5.0/media/kapi/v4l2-controls.html#active-and-grabbed-controls.

p.s. I know, VP9 seems similar, though arguably that was copied from jpeg, for
which it seems totally save to change the quality at run-time.

No, wasn't copied from JPEG :-) I just didn't realize this was an
issue, but it is
given the bit_depth affects the buffers so you are correct, it needs
to be fixed for VP9 too.

Thanks!
Ezequiel

quoted

+             break;
+     default:
+             return -EINVAL;
+     }
+
+     return 0;
+}
+
+
 static const struct v4l2_ctrl_ops hantro_ctrl_ops = {
      .try_ctrl = hantro_try_ctrl,
 };

@@ -336,6 +355,12 @@ static const struct v4l2_ctrl_ops hantro_vp9_ctrl_ops = {
      .s_ctrl = hantro_vp9_s_ctrl,
 };

+static const struct v4l2_ctrl_ops hantro_av1_ctrl_ops = {
+     .try_ctrl = hantro_try_ctrl,
+     .s_ctrl = hantro_av1_s_ctrl,
+};
+
+
 #define HANTRO_JPEG_ACTIVE_MARKERS   (V4L2_JPEG_ACTIVE_MARKER_APP0 | \
                                       V4L2_JPEG_ACTIVE_MARKER_COM | \
                                       V4L2_JPEG_ACTIVE_MARKER_DQT | \

@@ -513,6 +538,7 @@ static const struct hantro_ctrl controls[] = {
              .codec = HANTRO_AV1_DECODER,
              .cfg = {
                      .id = V4L2_CID_STATELESS_AV1_SEQUENCE,
+                     .ops = &hantro_av1_ctrl_ops,
              },
      }, {
              .codec = HANTRO_AV1_DECODER,

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