On Wed, 14 Apr 2010, Guennadi Liakhovetski wrote:
> Interpretation of the V4L2 API specification, according to which the
> VIDIOC_S_CROP ioctl for capture devices shall set the input window and
> preserve the scales, thus possibly changing the output window, seems to be
> incorrect. Switch to using a more intuitive definition, i.e., to
> preserving the output format while changing scales.
>
> Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@xxxxxx>
> ---
>
> Val, I do not have any mt9t031 hardware any more, could you, please, test
> this patch and verify, that it does indeed do, what's described above?
There hasn't been any replies to this, so, I presume, this patch cannot be
tested at present. Therefore I'm going to leave it out of my pull requests
until it gets tested somehow.
Thanks
Guennadi
>
> diff --git a/drivers/media/video/mt9t031.c b/drivers/media/video/mt9t031.c
> index a9061bf..a604fa0 100644
> --- a/drivers/media/video/mt9t031.c
> +++ b/drivers/media/video/mt9t031.c
> @@ -63,6 +63,8 @@
> struct mt9t031 {
> struct v4l2_subdev subdev;
> struct v4l2_rect rect; /* Sensor window */
> + unsigned int out_width;
> + unsigned int out_height;
> int model; /* V4L2_IDENT_MT9T031* codes from v4l2-chip-ident.h */
> u16 xskip;
> u16 yskip;
> @@ -284,6 +286,26 @@ static u16 mt9t031_skip(s32 *source, s32 target, s32 max)
> return skip;
> }
>
> +static u16 mt9t031_skip_out(s32 *source, s32 *target)
> +{
> + unsigned int skip;
> +
> + if (*source < *target + *target / 2) {
> + *target = *source;
> + return 1;
> + }
> +
> + skip = (*source + *target / 2) / *target;
> + if (skip > 8) {
> + skip = 8;
> + *target = (*source + 4) / 8;
> + }
> + /* We try to preserve input, but with division we have to adjust it too */
> + *source = *target * skip;
> +
> + return skip;
> +}
> +
> /* rect is the sensor rectangle, the caller guarantees parameter validity */
> static int mt9t031_set_params(struct i2c_client *client,
> struct v4l2_rect *rect, u16 xskip, u16 yskip)
> @@ -393,6 +415,7 @@ static int mt9t031_s_crop(struct v4l2_subdev *sd, struct v4l2_crop *a)
> struct v4l2_rect rect = a->c;
> struct i2c_client *client = sd->priv;
> struct mt9t031 *mt9t031 = to_mt9t031(client);
> + u16 xskip, yskip;
>
> rect.width = ALIGN(rect.width, 2);
> rect.height = ALIGN(rect.height, 2);
> @@ -403,7 +426,10 @@ static int mt9t031_s_crop(struct v4l2_subdev *sd, struct v4l2_crop *a)
> soc_camera_limit_side(&rect.top, &rect.height,
> MT9T031_ROW_SKIP, MT9T031_MIN_HEIGHT, MT9T031_MAX_HEIGHT);
>
> - return mt9t031_set_params(client, &rect, mt9t031->xskip, mt9t031->yskip);
> + xskip = mt9t031_skip_out(&rect.width, &mt9t031->out_width);
> + yskip = mt9t031_skip_out(&rect.height, &mt9t031->out_height);
> +
> + return mt9t031_set_params(client, &rect, xskip, yskip);
> }
>
> static int mt9t031_g_crop(struct v4l2_subdev *sd, struct v4l2_crop *a)
> @@ -437,8 +463,8 @@ static int mt9t031_g_fmt(struct v4l2_subdev *sd,
> struct i2c_client *client = sd->priv;
> struct mt9t031 *mt9t031 = to_mt9t031(client);
>
> - mf->width = mt9t031->rect.width / mt9t031->xskip;
> - mf->height = mt9t031->rect.height / mt9t031->yskip;
> + mf->width = mt9t031->out_width;
> + mf->height = mt9t031->out_height;
> mf->code = V4L2_MBUS_FMT_SBGGR10_1X10;
> mf->colorspace = V4L2_COLORSPACE_SRGB;
> mf->field = V4L2_FIELD_NONE;
> @@ -455,8 +481,9 @@ static int mt9t031_s_fmt(struct v4l2_subdev *sd,
> struct v4l2_rect rect = mt9t031->rect;
>
> /*
> - * try_fmt has put width and height within limits.
> - * S_FMT: use binning and skipping for scaling
> + * try_fmt has put width and height within limits. Note: when converting
> + * to a generic v4l2-subdev driver, try_fmt will have to be called
> + * explicitly. S_FMT: use binning and skipping for scaling.
> */
> xskip = mt9t031_skip(&rect.width, mf->width, MT9T031_MAX_WIDTH);
> yskip = mt9t031_skip(&rect.height, mf->height, MT9T031_MAX_HEIGHT);
> @@ -464,6 +491,9 @@ static int mt9t031_s_fmt(struct v4l2_subdev *sd,
> mf->code = V4L2_MBUS_FMT_SBGGR10_1X10;
> mf->colorspace = V4L2_COLORSPACE_SRGB;
>
> + mt9t031->out_width = mf->width;
> + mt9t031->out_height = mf->height;
> +
> /* mt9t031_set_params() doesn't change width and height */
> return mt9t031_set_params(client, &rect, xskip, yskip);
> }
> @@ -807,6 +837,9 @@ static int mt9t031_probe(struct i2c_client *client,
> mt9t031->rect.width = MT9T031_MAX_WIDTH;
> mt9t031->rect.height = MT9T031_MAX_HEIGHT;
>
> + mt9t031->out_width = MT9T031_MAX_WIDTH;
> + mt9t031->out_height = MT9T031_MAX_HEIGHT;
> +
> /*
> * Simulated autoexposure. If enabled, we calculate shutter width
> * ourselves in the driver based on vertical blanking and frame width
>
---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/
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