[PATCH 1/6] media: verisilicon: Enforce a minimum CAPTURE sizeimage for the encoder

[Arun Iyengar via B4 Relay]

From: Arun Iyengar <aiyengar1990 at gmail.com>

For coded formats hantro_try_fmt() only computes sizeimage when the
application passes 0, and otherwise accepts any value. On the encoder
that lets the CAPTURE buffers be far too small for the selected
resolution.

This is easy to hit: "v4l2-ctl --set-fmt-video=width=1920,height=1080,
pixelformat=JPEG" does G_FMT, modifies the size and calls S_FMT, so it
passes back the 6768 byte sizeimage of the 96x32 default format. The
driver accepts it for 1920x1088, the hardware runs out of stream buffer
on every frame and the encoder only produces empty buffers.

The stateful encoder specification lets the encoder adjust sizeimage to
match hardware requirements. For the encoder, clamp the requested
sizeimage up to the worst-case frame size already used as the default,
while still allowing applications to ask for larger buffers. The
decoder behaviour is unchanged.

Signed-off-by: Arun Iyengar <aiyengar1990 at gmail.com>
---
 drivers/media/platform/verisilicon/hantro_v4l2.c | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/media/platform/verisilicon/hantro_v4l2.c b/drivers/media/platform/verisilicon/hantro_v4l2.c
index 83af9fa1ce94..c022b978f72b 100644
--- a/drivers/media/platform/verisilicon/hantro_v4l2.c
+++ b/drivers/media/platform/verisilicon/hantro_v4l2.c
@@ -386,14 +386,24 @@ static int hantro_try_fmt(const struct hantro_ctx *ctx,
 			pix_mp->plane_fmt[0].sizeimage +=
 				hantro_av1_mv_size(pix_mp->width,
 						   pix_mp->height);
-	} else if (!pix_mp->plane_fmt[0].sizeimage) {
+	} else {
+		u32 max_size = fmt->header_size +
+			pix_mp->width * pix_mp->height * fmt->max_depth;
+		u32 *sizeimage = &pix_mp->plane_fmt[0].sizeimage;
+
 		/*
 		 * For coded formats the application can specify
 		 * sizeimage. If the application passes a zero sizeimage,
 		 * let's default to the maximum frame size.
+		 *
+		 * The encoder must also be able to fit the worst-case
+		 * frame for the current resolution, so never let the
+		 * application go below it. Larger values are kept.
 		 */
-		pix_mp->plane_fmt[0].sizeimage = fmt->header_size +
-			pix_mp->width * pix_mp->height * fmt->max_depth;
+		if (ctx->is_encoder)
+			*sizeimage = max(*sizeimage, max_size);
+		else if (!*sizeimage)
+			*sizeimage = max_size;
 	}
 
 	return 0;

-- 
2.55.0