[PATCH 2/3] ov7670: disable QVGA mode

[PATCH 2/3] ov7670: disable QVGA mode

[Daniel Drake]

Capturing at this resolution results in an ugly green horizontal line
at the left side of the image. Disable until fixed.

http://dev.laptop.org/ticket/10231

Signed-off-by: Daniel Drake <dsd@laptop.org>
---
 drivers/media/video/ov7670.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/drivers/media/video/ov7670.c b/drivers/media/video/ov7670.c
index 7017e5c..9fffcdd 100644
--- a/drivers/media/video/ov7670.c
+++ b/drivers/media/video/ov7670.c
@@ -672,7 +672,9 @@ static struct ov7670_win_size {
 		.vstop		= 494,
 		.regs 		= NULL,
 	},
-	/* QVGA */
+#if 0
+	/* QVGA - disabled due to ugly green line.
+	 * http://dev.laptop.org/ticket/10231 */
 	{
 		.width		= QVGA_WIDTH,
 		.height		= QVGA_HEIGHT,
@@ -683,6 +685,7 @@ static struct ov7670_win_size {
 		.vstop		= 494,
 		.regs 		= NULL,
 	},
+#endif
 #if 0
 	/* QCIF - disabled because it only shows a small portion of sensor FOV */
 	{
-- 
1.7.2.3

Re: [PATCH 2/3] ov7670: disable QVGA mode

[Jonathan Corbet]

On Fri,  8 Oct 2010 22:04:18 +0100 (BST)
Daniel Drake <dsd@laptop.org> wrote:

> Capturing at this resolution results in an ugly green horizontal line
> at the left side of the image. Disable until fixed.

A problem like that will be at the controller level, not the sensor
level.  Given that this is an XO-1 report, I'd assume something
requires tweaking in the cafe_ccic driver.  I wasn't aware of this; I
know it worked once upon a time.

Again, given that ov7670 sensors can appear elsewhere, I'd be inclined
not to turn off this functionality because of this problem.

jon

Re: [PATCH 2/3] ov7670: disable QVGA mode

[Daniel Drake]

On 8 October 2010 22:13, Jonathan Corbet <corbet@lwn.net> wrote:
> A problem like that will be at the controller level, not the sensor
> level.  Given that this is an XO-1 report, I'd assume something
> requires tweaking in the cafe_ccic driver.  I wasn't aware of this; I
> know it worked once upon a time.

I reported it 3 months ago
http://dev.laptop.org/ticket/10231

Are you interested in working on this?
I'd have no idea where to start.

I'm not so convinced that it's a controller problem rather than a
sensor one, given that it says the sensor register values were
determined empirically rather than from docs.

Thanks,
Daniel

Re: [PATCH 2/3] ov7670: disable QVGA mode

[Mauro Carvalho Chehab]

Em 08-10-2010 18:18, Daniel Drake escreveu:
> On 8 October 2010 22:13, Jonathan Corbet <corbet@lwn.net> wrote:
>> A problem like that will be at the controller level, not the sensor
>> level.  Given that this is an XO-1 report, I'd assume something
>> requires tweaking in the cafe_ccic driver.  I wasn't aware of this; I
>> know it worked once upon a time.
> 
> I reported it 3 months ago
> http://dev.laptop.org/ticket/10231
> 
> Are you interested in working on this?
> I'd have no idea where to start.

It maybe at one or at the other. What happens is that, in general, both the controller
and the sensor discards the initial/final parts of a line. The visible area of the image
is (generally) configurable on both. If the visible area doesn't match, you'll see a vertical
or a horizontal line.

This is configured by hstart and hstop, in the case of ov sensors. If you wanna try to fix, all 
you need to do is do move the start/stop window, for example, subtracting 2 on both hstart/hstop. 
If this doesn't fix, try 3, 4, ...

Yet, as Jon mentioned, if this works on XO-1, the better fix would be to adjust the screen visible
area at XO-2 visible area setup (sometimes called "crop area" at datasheets).


> 
> I'm not so convinced that it's a controller problem rather than a
> sensor one, given that it says the sensor register values were
> determined empirically rather than from docs.
> 
> Thanks,
> Daniel
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