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?
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
--
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