media: hantro: Add quirk for NV12/NV12_4L4 capture format

The G2 core decoder engine produces NV12_4L4 format,
which is a simple NV12 4x4 tiled format. The driver currently
hides this format by always enabling the post-processor engine,
and therefore offering NV12 directly.

This is done without using the logic in hantro_postproc.c
and therefore makes it difficult to add VP9 cleanly.

Since fixing this is not easy, add a small quirk to force
NV12 if HEVC was configured, but otherwise declare NV12_4L4
as the pixel format in imx8mq_vpu_g2_variant.dec_fmts.

This will be used by the VP9 decoder which will be added soon.

Signed-off-by: Ezequiel Garcia <[e-mail]>
Signed-off-by: Andrzej Pietrasiewicz <[e-mail]>
Signed-off-by: Hans Verkuil <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

drivers/staging/media/hantro/hantro_v4l2.c

···
 	bool skip_mode_none;
 
 	/*
+	 * The HEVC decoder on the G2 core needs a little quirk to offer NV12
+	 * only on the capture side. Once the post-processor logic is used,
+	 * we will be able to expose NV12_4L4 and NV12 as the other cases,
+	 * and therefore remove this quirk.
+	 */
+	if (capture && ctx->vpu_src_fmt->fourcc == V4L2_PIX_FMT_HEVC_SLICE) {
+		if (f->index == 0) {
+			f->pixelformat = V4L2_PIX_FMT_NV12;
+			return 0;
+		}
+		return -EINVAL;
+	}
+
+	/*
 	 * When dealing with an encoder:
 	 *  - on the capture side we want to filter out all MODE_NONE formats.
 	 *  - on the output side we want to filter out all formats that are

drivers/staging/media/hantro/imx8m_vpu_hw.c

···
 
 static const struct hantro_fmt imx8m_vpu_g2_dec_fmts[] = {
 	{
-		.fourcc = V4L2_PIX_FMT_NV12,
+		.fourcc = V4L2_PIX_FMT_NV12_4L4,
 		.codec_mode = HANTRO_MODE_NONE,
 	},
 	{