media: vimc: Enable set resolution at the scaler src pad

Modify the scaler subdevice to accept setting the resolution of the source
pad (previously the source resolution would always be 3 times the sink for
both dimensions). Now any resolution can be set at src (even smaller ones)
and the sink video will be scaled to match it.

Test example: With the vimc module up (using the default vimc topology)
media-ctl -d platform:vimc -V '"Sensor A":0[fmt:SBGGR8_1X8/640x480]'
media-ctl -d platform:vimc -V '"Debayer A":0[fmt:SBGGR8_1X8/640x480]'
media-ctl -d platform:vimc -V '"Scaler":0[fmt:RGB888_1X24/640x480]'
media-ctl -d platform:vimc -V '"Scaler":0[crop:(100,50)/400x150]'
media-ctl -d platform:vimc -V '"Scaler":1[fmt:RGB888_1X24/300x700]'
v4l2-ctl -z platform:vimc -d "RGB/YUV Capture" -v width=300,height=700
v4l2-ctl -z platform:vimc -d "Raw Capture 0" -v pixelformat=BA81
v4l2-ctl --stream-mmap --stream-count=10 -z platform:vimc -d "RGB/YUV Capture" \
	--stream-to=test.raw

The result will be a cropped stream that can be checked with the command
ffplay -loglevel warning -v info -f rawvideo -pixel_format rgb24 \
	-video_size "300x700" test.raw
Co-developed-by: Gabriela Bittencourt <gabrielabittencourt00@gmail.com>
Signed-off-by: Gabriela Bittencourt <gabrielabittencourt00@gmail.com>
Co-developed-by: Gabriel Francisco Mandaji <gfmandaji@gmail.com>
Signed-off-by: Gabriel Francisco Mandaji <gfmandaji@gmail.com>
Signed-off-by: Pedro Terra <pedro@terraco.de>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

Documentation/admin-guide/media/vimc.rst

@@ -61,9 +61,10 @@ vimc-debayer:
 	* 1 Pad source
 
 vimc-scaler:
-	Scale up the image by a factor of 3. E.g.: a 640x480 image becomes a
-        1920x1440 image. (this value can be configured, see at
-        `Module options`_).
+	Re-size the image to meet the source pad resolution. E.g.: if the sync
+	pad is configured to 360x480 and the source to 1280x720, the image will
+	be stretched to fit the source resolution. Works for any resolution
+	within the vimc limitations (even shrinking the image if necessary).
 	Exposes:
 
 	* 1 Pad sink
@@ -75,16 +76,3 @@ vimc-capture:
 
 	* 1 Pad sink
 	* 1 Pad source
-
-
-Module options
---------------
-
-Vimc has a module parameter to configure the driver.
-
-* ``sca_mult=<unsigned int>``
-
-        Image size multiplier factor to be used to multiply both width and
-        height, so the image size will be ``sca_mult^2`` bigger than the
-        original one. Currently, only supports scaling up (the default value
-        is 3).