[E3-hacking] [PATCH v3 3/6] SoC Camera: add driver for OV6650 sensor

[Guennadi Liakhovetski]

On Sat, 2 Oct 2010, Janusz Krzysztofik wrote:

> Saturday 02 October 2010 07:47:47 Guennadi Liakhovetski napisał(a):
> > Ok, let's take this one, but, please, address the below couple of minor
> > issues in an incremental patch.
> >
> > On Mon, 27 Sep 2010, Janusz Krzysztofik wrote:
> > > +/* write a register */
> > > +static int ov6650_reg_write(struct i2c_client *client, u8 reg, u8 val)
> > > +{
> > > +	int ret;
> > > +	unsigned char data[2] = { reg, val };
> > > +	struct i2c_msg msg = {
> > > +		.addr	= client->addr,
> > > +		.flags	= 0,
> > > +		.len	= 2,
> > > +		.buf	= data,
> > > +	};
> > > +
> > > +	ret = i2c_transfer(client->adapter, &msg, 1);
> > > +	usleep_range(100, 1000);
> >
> > So, 100us are enough? Then I'd just go with udelay(100).
> 
> Guennadi,
> I already tried with udelay(100), as you had suggested before, and it worked, 
> but then checkpatch.pl --sctirct told me:
> 
> "CHECK: usleep_range is preferred over udelay; see 
> Documentation/timers/timers-howto.txt
> +       udelay(100);"
> 
> So, I had read Documentation/timers/timers-howto.txt again and switched to 
> usleep_range, as it suggested.
> 
> Please confirm if you still prefere udelay(100) over usleep_range(), and I'll 
> change it back.

No, no, that's ok then...

> > > static bool is_unscaled_ok(int width, int height, struct v4l2_rect *rect)
> > > +{
> > > +	return (width > rect->width >> 1 || height > rect->height >> 1);
> > > +}
> >
> > Ok, just one more pair of brackets to remove;)
> 
> OK.
> 
> > > +
> > > +static u8 to_clkrc(struct v4l2_fract *timeperframe,
> > > +		unsigned long pclk_limit, unsigned long pclk_max)
> > > +{
> > > +	unsigned long pclk;
> > > +
> > > +	if (timeperframe->numerator && timeperframe->denominator)
> > > +		pclk = pclk_max * timeperframe->denominator /
> > > +				(FRAME_RATE_MAX * timeperframe->numerator);
> > > +	else
> > > +		pclk = pclk_max;
> > > +
> > > +	if (pclk_limit && pclk_limit < pclk)
> > > +		pclk = pclk_limit;
> > > +
> > > +	return (pclk_max - 1) / pclk;
> > > +}
> > > +
> > > +/* set the format we will capture in */
> > > +static int ov6650_s_fmt(struct v4l2_subdev *sd, struct
> > > v4l2_mbus_framefmt *mf) +{
> > > +	struct i2c_client *client = sd->priv;
> > > +	struct soc_camera_device *icd = client->dev.platform_data;
> > > +	struct soc_camera_sense *sense = icd->sense;
> > > +	struct ov6650 *priv = to_ov6650(client);
> > > +	bool half_scale = !is_unscaled_ok(mf->width, mf->height, &priv->rect);
> > > +	struct v4l2_crop a = {
> > > +		.type = V4L2_BUF_TYPE_VIDEO_CAPTURE,
> > > +		.c = {
> > > +			.left	= priv->rect.left + (priv->rect.width >> 1) -
> > > +					(mf->width >> (1 - half_scale)),
> > > +			.top	= priv->rect.top + (priv->rect.height >> 1) -
> > > +					(mf->height >> (1 - half_scale)),
> > > +			.width	= mf->width << half_scale,
> > > +			.height	= mf->height << half_scale,
> > > +		},
> > > +	};
> >
> > Hm, this seems wrong to me... You calculate left and top to preserve the
> > center, right? 
> 
> Exactly.
> 
> > This is good, but: if output is unscaled, you want 
> >
> > 	.left = priv->rect.left + (priv->rect.width - mf->width) / 2;
> 
> 	== priv->rect.left +  priv->rect.width  / 2  -   mf->width        /  2
> 	== priv->rect.left + (priv->rect.width >> 1) - ( mf->width       >>  1)
> 	== priv->rect.left + (priv->rect.width >> 1) - ( mf->width       >> (1 - 0))
> >
> > in this case half_scale = 0 and the above is correct. Now, is the output
> > is scaled, you want
> >
> > 	.left = priv->rect.left + (priv->rect.width - mf->width * 2) / 2;
> 
> 	== priv->rect.left +  priv->rect.width  / 2  -   mf->width  * 2   /  2
> 	== priv->rect.left + (priv->rect.width >> 1) - ((mf->width << 1) >>  1)
> 	== priv->rect.left + (priv->rect.width >> 1) - ( mf->width       >> (1 - 1))
> 
> > which is not, what you have above. Am I missing anything?
> 
> One of us must be ;).

Ok, good, then it's me:)

> > > +	case V4L2_MBUS_FMT_UYVY8_2X8:
> > > +		dev_dbg(&client->dev, "pixel format YUYV8_2X8_BE\n");
> > > +		if (half_scale) {
> > > +			coma_mask |= COMA_RGB | COMA_BW | COMA_WORD_SWAP;
> > > +			coma_set |= COMA_BYTE_SWAP;
> > > +		} else {
> > > +			coma_mask |= COMA_RGB | COMA_BW;
> > > +			coma_set |= COMA_BYTE_SWAP | COMA_WORD_SWAP;
> > > +		}
> > > +		break;
> > > +	case V4L2_MBUS_FMT_VYUY8_2X8:
> > > +		dev_dbg(&client->dev, "pixel format YVYU8_2X8_BE (untested)\n");
> > > +		if (half_scale) {
> > > +			coma_mask |= COMA_RGB | COMA_BW;
> > > +			coma_set |= COMA_BYTE_SWAP | COMA_WORD_SWAP;
> > > +		} else {
> > > +			coma_mask |= COMA_RGB | COMA_BW | COMA_WORD_SWAP;
> > > +			coma_set |= COMA_BYTE_SWAP;
> > > +		}
> > > +		break;
> >
> > ...since there anyway will be an incremental patch . what does
> > word-swapping have to do with scaling?...
> 
> A hardware (firmware) bug perhaps? All I can say is that I had found out it 
> worked like this for me before, and I've just ensured it still does.
> 
> > > +	case V4L2_MBUS_FMT_SBGGR8_1X8:
> > > +		dev_dbg(&client->dev, "pixel format SBGGR8_1X8 (untested)\n");
> > > +		coma_mask |= COMA_BW | COMA_BYTE_SWAP | COMA_WORD_SWAP;
> > > +		coma_set |= COMA_RAW_RGB | COMA_RGB;
> > > +		break;
> > > +	case 0:
> > > +		break;
> >
> > 0 is defined as reserved... What for do you need it here?
> 
> This I have mentioned in my v2 -> v3 changes list:
> 
> > - add support for geometry only change to s_fmt, 
> 
> I've tried to follow a pattern copied from mt9v022.c:
> 
> +        case 0:
> +		/* No format change, only geometry */
> +		break;
> 
> but now I see I've missed the comment unfortunately. Please specify if you 
> prefere to have it dropped or documented.

Well, what you're actually missing here is this:

http://git.linuxtv.org/media_tree.git?a=commitdiff;h=4222226680cc25e48dc264f4de2dd81e55fd3580

Thanks
Guennadi
---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/