lkml.org 
[lkml]   [2020]   [Sep]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH v2 5/5] media: mt9p031: Fix corrupted frame after restarting stream
Date
From: Dirk Bender <d.bender@phytec.de>

To prevent corrupted frames after starting and stopping the sensor it's
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 <d.bender@phytec.de>
Signed-off-by: Stefan Riedmueller <s.riedmueller@phytec.de>
---
No changes in v2
---
drivers/media/i2c/mt9p031.c | 25 +++++++++++++++++++++++++
1 file changed, 25 insertions(+)

diff --git a/drivers/media/i2c/mt9p031.c b/drivers/media/i2c/mt9p031.c
index d10457361e6c..d59f66e3dcf3 100644
--- a/drivers/media/i2c/mt9p031.c
+++ b/drivers/media/i2c/mt9p031.c
@@ -80,6 +80,8 @@
#define MT9P031_PIXEL_CLOCK_SHIFT(n) ((n) << 8)
#define MT9P031_PIXEL_CLOCK_DIVIDE(n) ((n) << 0)
#define MT9P031_FRAME_RESTART 0x0b
+#define MT9P031_FRAME_RESTART_SET (1 << 0)
+#define MT9P031_FRAME_PAUSE_RESTART_SET (1 << 1)
#define MT9P031_SHUTTER_DELAY 0x0c
#define MT9P031_RST 0x0d
#define MT9P031_RST_ENABLE 1
@@ -483,9 +485,25 @@ 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) {
+ val = mt9p031_read(client, MT9P031_FRAME_RESTART);
+
+ /* enable pause restart */
+ val |= MT9P031_FRAME_PAUSE_RESTART_SET;
+ ret = mt9p031_write(client, MT9P031_FRAME_RESTART, val);
+ if (ret < 0)
+ return ret;
+
+ /* enable restart + keep pause restart set */
+ val |= MT9P031_FRAME_RESTART_SET;
+ ret = mt9p031_write(client, MT9P031_FRAME_RESTART, val);
+ if (ret < 0)
+ return ret;
+
/* Stop sensor readout */
ret = mt9p031_set_output_control(mt9p031,
MT9P031_OUTPUT_CONTROL_CEN, 0);
@@ -505,6 +523,13 @@ static int mt9p031_s_stream(struct v4l2_subdev *subdev, int enable)
if (ret < 0)
return ret;

+ val = mt9p031_read(client, MT9P031_FRAME_RESTART);
+ /* disable reset + pause restart */
+ val &= ~MT9P031_FRAME_PAUSE_RESTART_SET;
+ ret = mt9p031_write(client, MT9P031_FRAME_RESTART, val);
+ if (ret < 0)
+ return ret;
+
return mt9p031_pll_enable(mt9p031);
}

--
2.25.1
\
 
 \ /
  Last update: 2020-09-30 12:53    [W:0.144 / U:0.628 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site