From: Hans de Goede <johannes.goede@oss.qualcomm.com>
Date: Tue, 30 Dec 2025 17:03:02 +0000 (+0100)
Subject: media: mt9m114: Tweak default hblank and vblank for more accurate fps
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=432d109333afd674a416a061b98264bfcd5f0515;p=thirdparty%2Fkernel%2Flinux.git

media: mt9m114: Tweak default hblank and vblank for more accurate fps

The PLL gets programmed to achieve a 48 MHz pixelclock, with the current
vblank + hblank defaults this results in a fps of:

48000000 / ((1296 + 307) * (976 + 23) = 29.974 fps

Tweak the defaults to get closer to 30 fps:

48000000 / ((1296 + 308) * (976 + 21) = 30.015 fps

This improves things from being 0.026 fps too low to 0.015 fps too high.

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans de Goede <johannes.goede@oss.qualcomm.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>
---

diff --git a/drivers/media/i2c/mt9m114.c b/drivers/media/i2c/mt9m114.c
index 0076723c5aa5b..a45e6709d1082 100644
--- a/drivers/media/i2c/mt9m114.c
+++ b/drivers/media/i2c/mt9m114.c
@@ -337,8 +337,8 @@
  */
 #define MT9M114_MIN_HBLANK				303
 #define MT9M114_MIN_VBLANK				21
-#define MT9M114_DEF_HBLANK				307
-#define MT9M114_DEF_VBLANK				23
+#define MT9M114_DEF_HBLANK				308
+#define MT9M114_DEF_VBLANK				21
 
 #define MT9M114_DEF_FRAME_RATE				30
 #define MT9M114_MAX_FRAME_RATE				120