linux-kernel - [PATCH 1/3] media: i2c: imx219: Only use higher LLP

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Message-Id: <20250219-imx219_fixes_v2-v1-1-0e3f5dd9b024@ideasonboard.com>
Date: Wed, 19 Feb 2025 17:16:43 +0530
From: Jai Luthra <jai.luthra@...asonboard.com>
To: Sakari Ailus <sakari.ailus@...ux.intel.com>, 
 Dave Stevenson <dave.stevenson@...pberrypi.com>, 
 Mauro Carvalho Chehab <mchehab@...nel.org>
Cc: linux-media@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Jacopo Mondi <jacopo.mondi@...asonboard.com>, 
 Jai Luthra <jai.luthra@...asonboard.com>
Subject: [PATCH 1/3] media: i2c: imx219: Only use higher LLP_MIN for binned
 resolutions

The LLP_MIN of 3560 is only needed to fix artefacts seen with binned
resolutions. As increasing the LLP reduces the highest possible
framerate by ~3%, use the default minimum of 3448 for non-binned
resolutions.

Suggested-by: Dave Stevenson <dave.stevenson@...pberrypi.com>
Link: https://lore.kernel.org/linux-media/CAPY8ntC1-S6zKtDvmc6EgyxP+j6rTShuG8Dr8PKb9XQr2PeS_w@mail.gmail.com/
Signed-off-by: Jai Luthra <jai.luthra@...asonboard.com>
---
 drivers/media/i2c/imx219.c | 24 ++++++++++++++++--------
 1 file changed, 16 insertions(+), 8 deletions(-)

diff --git a/drivers/media/i2c/imx219.c b/drivers/media/i2c/imx219.c
index f662c9d755114265aad46c5cc7f5031b9bc0dbba..6e51a7af5e2a05cacefb201d96a9fbdc349f17d8 100644
--- a/drivers/media/i2c/imx219.c
+++ b/drivers/media/i2c/imx219.c
@@ -74,7 +74,8 @@
 #define IMX219_FLL_MAX			0xffff
 #define IMX219_VBLANK_MIN		32
 #define IMX219_REG_LINE_LENGTH_A	CCI_REG16(0x0162)
-#define IMX219_LLP_MIN			0x0de8
+#define IMX219_LLP_MIN			0x0d78
+#define IMX219_BINNED_LLP_MIN		0x0de8
 #define IMX219_LLP_MAX			0x7ff0
 
 #define IMX219_REG_X_ADD_STA_A		CCI_REG16(0x0164)
@@ -317,13 +318,13 @@ static const struct imx219_mode supported_modes[] = {
 		/* 8MPix 15fps mode */
 		.width = 3280,
 		.height = 2464,
-		.fll_def = 3415,
+		.fll_def = 3526,
 	},
 	{
 		/* 1080P 30fps cropped */
 		.width = 1920,
 		.height = 1080,
-		.fll_def = 1707,
+		.fll_def = 1763,
 	},
 	{
 		/* 2x2 binned 60fps mode */
@@ -901,7 +902,7 @@ static int imx219_set_pad_format(struct v4l2_subdev *sd,
 	if (fmt->which == V4L2_SUBDEV_FORMAT_ACTIVE) {
 		int exposure_max;
 		int exposure_def;
-		int hblank;
+		int hblank, llp_min;
 		int pixel_rate;
 
 		/* Update limits and set FPS to default */
@@ -918,6 +919,17 @@ static int imx219_set_pad_format(struct v4l2_subdev *sd,
 					 imx219->exposure->minimum,
 					 exposure_max, imx219->exposure->step,
 					 exposure_def);
+
+		/*
+		 * With analog binning the default minimum line length of 3448
+		 * can cause artefacts because the ADC operates on two lines
+		 * together. Switch to higher minimum of 3560 if we are binning.
+		 */
+		llp_min = (bin_h || bin_v) ? IMX219_BINNED_LLP_MIN :
+					     IMX219_LLP_MIN;
+		__v4l2_ctrl_modify_range(imx219->hblank, llp_min - mode->width,
+					 IMX219_LLP_MAX - mode->width, 1,
+					 llp_min - mode->width);
 		/*
 		 * Retain PPL setting from previous mode so that the
 		 * line time does not change on a mode change.
@@ -926,10 +938,6 @@ static int imx219_set_pad_format(struct v4l2_subdev *sd,
 		 * mode width subtracted.
 		 */
 		hblank = prev_line_len - mode->width;
-		__v4l2_ctrl_modify_range(imx219->hblank,
-					 IMX219_LLP_MIN - mode->width,
-					 IMX219_LLP_MAX - mode->width, 1,
-					 IMX219_LLP_MIN - mode->width);
 		__v4l2_ctrl_s_ctrl(imx219->hblank, hblank);
 
 		/* Scale the pixel rate based on the mode specific factor */

-- 
2.48.1