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

Steve Longerbeam
2017-02-17T01:33:14Z

On 02/16/2017 05:02 AM, Philipp Zabel wrote:
> On Wed, 2017-02-15 at 18:19 -0800, Steve Longerbeam wrote:
<snip>
>> +
>> +- 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) ?
>> + V4L2_COLORSPACE_SRGB : V4L2_COLORSPACE_SMPTE170M;
>> +}
>
> 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.

Steve