Hi Laurent,
On 02.10.20 02:05, Laurent Pinchart wrote:
Hi Stefan,
Thank you for the patch.
On Wed, Sep 30, 2020 at 12:51:33PM +0200, Stefan Riedmueller wrote:
From: Dirk Bender <d.bender@xxxxxxxxx>
To prevent corrupted frames after starting and stopping the sensor it's
s/it's/its/
thanks, I'll fix that.
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@xxxxxxxxx>
Signed-off-by: Stefan Riedmueller <s.riedmueller@xxxxxxxxx>
---
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)
The fields are named Restart and Pause_Restart, I would drop _SET. Could
you also sort them from MSB to LSB as for the other registers ? Using
BIT() would be good too, although this could be done as an additional
patch to convert all the existing macros.
I'll do that. Also I will rename the register to MT9P031_RESTART and the
bits to MT9P031_FRAME_RESTART and MT9P031_FRAME_PAUSE_RESTART.
#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);
Do you need to read the register ? Can't you write
MT9P031_FRAME_PAUSE_RESTART_SET and then MT9P031_FRAME_PAUSE_RESTART_SET
| MT9P031_FRAME_RESTART_SET ? And actually, can't we just write both
bits in one go, do we need two writes ?
I think you're right we don't necessarily need to read the registers. The
only other bit is not used by the driver.
But I think we do need two separate writes, at least that is what the
datasheet states.
So I would drop the read but keep both write, ok?
+
+ /* 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;
Same here, I think you can simply write MT9P031_FRAME_PAUSE_RESTART_SET.
I'll drop the read here as well. But I need to make sure, that the Restart
Bit is not cleared manually here.
Regards,
Stefan
+ ret = mt9p031_write(client, MT9P031_FRAME_RESTART, val);
+ if (ret < 0)
+ return ret;
+
return mt9p031_pll_enable(mt9p031);
}
