linux-kernel - [PATCH 5/6] media: stm32: dcmipp: byteproc: only allow compose with 8/16bit fmts

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Message-ID: <20251219-stm32-dcmipp-enhancements-v1-5-e2f8d46f022c@foss.st.com>
Date: Fri, 19 Dec 2025 15:30:39 +0100
From: Alain Volmat <alain.volmat@...s.st.com>
To: Hugues Fruchet <hugues.fruchet@...s.st.com>,
        Mauro Carvalho Chehab
	<mchehab@...nel.org>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        "Alexandre
 Torgue" <alexandre.torgue@...s.st.com>,
        Sakari Ailus
	<sakari.ailus@...ux.intel.com>,
        Hans Verkuil <hverkuil@...nel.org>
CC: <linux-media@...r.kernel.org>, <linux-stm32@...md-mailman.stormreply.com>,
        <linux-arm-kernel@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
        "Alain Volmat" <alain.volmat@...s.st.com>
Subject: [PATCH 5/6] media: stm32: dcmipp: byteproc: only allow compose
 with 8/16bit fmts

Since the byteproc is working at byte level, it is not possible to
perform decimation with formats other than 8 or 16 bit per pixel.
Ensure any other format won't be able to set a compose.

Signed-off-by: Alain Volmat <alain.volmat@...s.st.com>
---
 .../media/platform/st/stm32/stm32-dcmipp/dcmipp-byteproc.c   | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/media/platform/st/stm32/stm32-dcmipp/dcmipp-byteproc.c b/drivers/media/platform/st/stm32/stm32-dcmipp/dcmipp-byteproc.c
index f45a3027f8f3..f9e4a3a9ef3f 100644
--- a/drivers/media/platform/st/stm32/stm32-dcmipp/dcmipp-byteproc.c
+++ b/drivers/media/platform/st/stm32/stm32-dcmipp/dcmipp-byteproc.c
@@ -131,6 +131,8 @@ static void dcmipp_byteproc_adjust_crop(struct v4l2_rect *r,
 static void dcmipp_byteproc_adjust_compose(struct v4l2_rect *r,
 					   const struct v4l2_mbus_framefmt *fmt)
 {
+	const struct dcmipp_byteproc_pix_map *vpix;
+
 	r->top = 0;
 	r->left = 0;
 
@@ -142,6 +144,14 @@ static void dcmipp_byteproc_adjust_compose(struct v4l2_rect *r,
 		return;
 	}
 
+	/* Prevent compose on formats which are not 1 or 2 bytes per pixel */
+	vpix = dcmipp_byteproc_pix_map_by_code(fmt->code);
+	if (vpix->bpp != 1 && vpix->bpp != 2) {
+		r->width = fmt->width;
+		r->height = fmt->height;
+		return;
+	}
+
 	/* Adjust height - we can only perform 1/2 decimation */
 	if (r->height <= (fmt->height / 2))
 		r->height = fmt->height / 2;
@@ -149,7 +159,7 @@ static void dcmipp_byteproc_adjust_compose(struct v4l2_rect *r,
 		r->height = fmt->height;
 
 	/* Adjust width /2 or /4 for 8bits formats and /2 for 16bits formats */
-	if (fmt->code == MEDIA_BUS_FMT_Y8_1X8 && r->width <= (fmt->width / 4))
+	if (vpix->bpp == 1 && r->width <= (fmt->width / 4))
 		r->width = fmt->width / 4;
 	else if (r->width <= (fmt->width / 2))
 		r->width = fmt->width / 2;

-- 
2.34.1