[PATCH v3 5/6] media: mt9p031: Fix corrupted frame after restarting stream
From: Stefan Riedmueller <hidden>
Date: 2021-07-02 09:59:43
Also in:
linux-media, lkml
Subsystem:
media input infrastructure (v4l/dvb), mt9p031 aptina camera sensor, the rest, v4l2 camera sensor drivers · Maintainers:
Mauro Carvalho Chehab, Laurent Pinchart, Linus Torvalds, Sakari Ailus
From: Dirk Bender <redacted> To prevent corrupted frames after starting and stopping the sensor its datasheet specifies a specific pause sequence to follow: Stopping: Set Pause_Restart Bit -> Set Restart Bit -> Set Chip_Enable Off Restarting: Set Chip_Enable On -> Clear Pause_Restart Bit The Restart Bit is cleared automatically and must not be cleared manually as this would cause undefined behavior. Signed-off-by: Dirk Bender <redacted> Signed-off-by: Stefan Riedmueller <redacted> --- drivers/media/i2c/mt9p031.c | 28 +++++++++++++++++++++++++++- 1 file changed, 27 insertions(+), 1 deletion(-)
diff --git a/drivers/media/i2c/mt9p031.c b/drivers/media/i2c/mt9p031.c
index 6a6f16df3f4a..3511c4ff350d 100644
--- a/drivers/media/i2c/mt9p031.c
+++ b/drivers/media/i2c/mt9p031.c@@ -79,7 +79,9 @@ #define MT9P031_PIXEL_CLOCK_INVERT (1 << 15) #define MT9P031_PIXEL_CLOCK_SHIFT(n) ((n) << 8) #define MT9P031_PIXEL_CLOCK_DIVIDE(n) ((n) << 0) -#define MT9P031_FRAME_RESTART 0x0b +#define MT9P031_RESTART 0x0b +#define MT9P031_FRAME_PAUSE_RESTART (1 << 1) +#define MT9P031_FRAME_RESTART (1 << 0) #define MT9P031_SHUTTER_DELAY 0x0c #define MT9P031_RST 0x0d #define MT9P031_RST_ENABLE 1
@@ -482,9 +484,23 @@ static int mt9p031_set_params(struct mt9p031 *mt9p031) static int mt9p031_s_stream(struct v4l2_subdev *subdev, int enable) { struct mt9p031 *mt9p031 = to_mt9p031(subdev); + struct i2c_client *client = v4l2_get_subdevdata(subdev); + int val; int ret; if (!enable) { + /* enable pause restart */ + val = MT9P031_FRAME_PAUSE_RESTART; + ret = mt9p031_write(client, MT9P031_RESTART, val); + if (ret < 0) + return ret; + + /* enable restart + keep pause restart set */ + val |= MT9P031_FRAME_RESTART; + ret = mt9p031_write(client, MT9P031_RESTART, val); + if (ret < 0) + return ret; + /* Stop sensor readout */ ret = mt9p031_set_output_control(mt9p031, MT9P031_OUTPUT_CONTROL_CEN, 0);
@@ -504,6 +520,16 @@ static int mt9p031_s_stream(struct v4l2_subdev *subdev, int enable) if (ret < 0) return ret; + /* + * - clear pause restart + * - don't clear restart as clearing restart manually can cause + * undefined behavior + */ + val = MT9P031_FRAME_RESTART; + ret = mt9p031_write(client, MT9P031_RESTART, val); + if (ret < 0) + return ret; + return mt9p031_pll_enable(mt9p031); }
--
2.25.1