linux-kernel - [PATCH v4 05/15] media: rcar-csi2: Optimize rcsi2_calc

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20251216-rcar-streams-v4-5-f28b4831cc67@ideasonboard.com>
Date: Tue, 16 Dec 2025 17:18:22 +0200
From: Tomi Valkeinen <tomi.valkeinen+renesas@...asonboard.com>
To: Niklas Söderlund <niklas.soderlund@...natech.se>, 
 Mauro Carvalho Chehab <mchehab@...nel.org>, 
 Sakari Ailus <sakari.ailus@...ux.intel.com>
Cc: linux-media@...r.kernel.org, linux-renesas-soc@...r.kernel.org, 
 linux-kernel@...r.kernel.org, 
 Niklas Söderlund <niklas.soderlund+renesas@...natech.se>, 
 Mauro Carvalho Chehab <mchehab+huawei@...nel.org>, 
 Laurent Pinchart <laurent.pinchart@...asonboard.com>, 
 Jacopo Mondi <jacopo.mondi@...asonboard.com>, 
 Tomi Valkeinen <tomi.valkeinen+renesas@...asonboard.com>, 
 Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>
Subject: [PATCH v4 05/15] media: rcar-csi2: Optimize rcsi2_calc_mbps()

With modern drivers supporting link-freq, we don't need to do any
calculations based on the bpp and number of lanes when figuring out the
link frequency. However, the code currently always runs code to get the
bpp and number of lanes.

Optimize the rcsi2_calc_mbps() so that we only do that when needed, i.e.
when querying the link-freq is not supported by the upstream subdevice.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen+renesas@...asonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>
---
 drivers/media/platform/renesas/rcar-csi2.c | 50 +++++++++++++++++-------------
 1 file changed, 29 insertions(+), 21 deletions(-)

diff --git a/drivers/media/platform/renesas/rcar-csi2.c b/drivers/media/platform/renesas/rcar-csi2.c
index a2a87c5bfd7c..7305cc4a04cb 100644
--- a/drivers/media/platform/renesas/rcar-csi2.c
+++ b/drivers/media/platform/renesas/rcar-csi2.c
@@ -1006,15 +1006,10 @@ static int rcsi2_get_active_lanes(struct rcar_csi2 *priv,
 static int rcsi2_calc_mbps(struct rcar_csi2 *priv,
 			   struct v4l2_subdev_state *state)
 {
-	const struct rcar_csi2_format *format;
-	struct v4l2_mbus_framefmt *fmt;
 	struct media_pad *remote_pad;
 	struct v4l2_subdev *source;
-	unsigned int lanes;
-	unsigned int bpp;
 	s64 freq;
 	u64 mbps;
-	int ret;
 
 	if (!priv->remote)
 		return -ENODEV;
@@ -1022,28 +1017,41 @@ static int rcsi2_calc_mbps(struct rcar_csi2 *priv,
 	source = priv->remote;
 	remote_pad = &source->entity.pads[priv->remote_pad];
 
-	ret = rcsi2_get_active_lanes(priv, &lanes);
-	if (ret)
-		return ret;
+	/*
+	 * First try to get the real link freq. If that fails, try the heuristic
+	 * method with bpp and lanes (but that only works for one route).
+	 */
+	freq = v4l2_get_link_freq(remote_pad, 0, 0);
+	if (freq < 0) {
+		const struct rcar_csi2_format *format;
+		const struct v4l2_mbus_framefmt *fmt;
+		unsigned int lanes;
+		unsigned int bpp;
+		int ret;
 
-	fmt = v4l2_subdev_state_get_format(state, RCAR_CSI2_SINK);
-	if (!fmt)
-		return -EINVAL;
+		ret = rcsi2_get_active_lanes(priv, &lanes);
+		if (ret)
+			return ret;
 
-	format = rcsi2_code_to_fmt(fmt->code);
-	if (!format)
-		return -EINVAL;
+		fmt = v4l2_subdev_state_get_format(state, RCAR_CSI2_SINK);
+		if (!fmt)
+			return -EINVAL;
 
-	bpp = format->bpp;
+		format = rcsi2_code_to_fmt(fmt->code);
+		if (!format)
+			return -EINVAL;
 
-	freq = v4l2_get_link_freq(remote_pad, bpp, 2 * lanes);
-	if (freq < 0) {
-		int ret = (int)freq;
+		bpp = format->bpp;
 
-		dev_err(priv->dev, "failed to get link freq for %s: %d\n",
-			source->name, ret);
+		freq = v4l2_get_link_freq(remote_pad, bpp, 2 * lanes);
+		if (freq < 0) {
+			int ret = (int)freq;
 
-		return ret;
+			dev_err(priv->dev, "failed to get link freq for %s: %d\n",
+				source->name, ret);
+
+			return ret;
+		}
 	}
 
 	mbps = div_u64(freq * 2, MEGA);

-- 
2.43.0