Re: [PATCH v4 18/36] media: Add i.MX media core driver

From: Steve Longerbeam
Date: Thu Feb 16 2017 - 20:33:24 EST

On 02/16/2017 05:02 AM, Philipp Zabel wrote:
On Wed, 2017-02-15 at 18:19 -0800, Steve Longerbeam wrote:
+- Clean up and move the ov5642 subdev driver to drivers/media/i2c, and
+ create the binding docs for it.

This is done already, right?

I cleaned up ov5640 and moved it to drivers/media/i2c with binding docs,
but not the ov5642 yet.

+- The Frame Interval Monitor could be exported to v4l2-core for
+ general use.
+- The subdev that is the original source of video data (referred to as
+ the "sensor" in the code), is called from various subdevs in the
+ pipeline in order to set/query the video standard ({g|s|enum}_std)
+ and to get/set the original frame interval from the capture interface
+ ([gs]_parm). Instead, the entities that need this info should call its
+ direct neighbor, and the neighbor should propagate the call to its
+ neighbor in turn if necessary.

Especially the [gs]_parm fix is necessary to present userspace with the
correct frame interval in case of frame skipping in the CSI.

Right, understood. I've added this to list of fixes for version 5.

What a pain though! It means propagating every call to g_frame_interval
upstream until a subdev "that cares" returns ret == 0 or
ret != -ENOIOCTLCMD. And that goes for any other chained subdev call
as well.

I've thought of writing something like a v4l2_chained_subdev_call()
macro to do this, but it would be a big macro.

+- At driver load time, the device-tree node that is the original source
+ (the "sensor"), is parsed to record its media bus configuration, and
+ this info is required in various subdevs to setup the pipeline.
+ Laurent Pinchart argues that instead the subdev should call its
+ neighbor's g_mbus_config op (which should be propagated if necessary)
+ to get this info. However Hans Verkuil is planning to remove the
+ g_mbus_config op. For now this driver uses the parsed DT mbus config
+ method until this issue is resolved.
diff --git a/drivers/staging/media/imx/imx-media-dev.c b/drivers/staging/media/imx/imx-media-dev.c
new file mode 100644
index 0000000..e2041ad
--- /dev/null
+++ b/drivers/staging/media/imx/imx-media-dev.c
+static inline u32 pixfmt_to_colorspace(const struct imx_media_pixfmt *fmt)
+ return (fmt->cs == IPUV3_COLORSPACE_RGB) ?

This ...

+int imx_media_mbus_fmt_to_pix_fmt(struct v4l2_pix_format *pix,
+ struct v4l2_mbus_framefmt *mbus,
+ const struct imx_media_pixfmt *cc)
+ u32 stride;
+ if (!cc) {
+ cc = imx_media_find_format(0, mbus->code, true, false);
+ if (!cc)
+ return -EINVAL;
+ }
+ stride = cc->planar ? mbus->width : (mbus->width * cc->bpp) >> 3;
+ pix->width = mbus->width;
+ pix->height = mbus->height;
+ pix->pixelformat = cc->fourcc;
+ pix->colorspace = pixfmt_to_colorspace(cc);

... is not right. The colorspace should be taken from the input pad
colorspace everywhere (except for the IC output pad in the future, once
that supports changing YCbCr encoding and quantization), not guessed
based on the media bus format.

Ok, will fix this to assign pix->colorspace to mbus->colorspace, after
all the subdevs assign colorspace values to their pads.