Re: [PATCH 00/23] media: imx: imx7-mipi-csis: Add i.MX8MM support / imx8mq support

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Martin,

On Thu, May 20, 2021 at 12:54:27PM +0200, Martin Kepplinger wrote:
> Am Mittwoch, dem 19.05.2021 um 18:46 +0300 schrieb Laurent Pinchart:
> > On Wed, May 19, 2021 at 05:21:11PM +0200, Martin Kepplinger wrote:
> > > Am Mittwoch, dem 19.05.2021 um 04:14 +0300 schrieb Laurent Pinchart:
> > > > On Tue, May 18, 2021 at 04:39:00PM +0200, Martin Kepplinger wrote:
> > > > > Am Sonntag, dem 16.05.2021 um 01:55 +0300 schrieb Laurent Pinchart:
> > > > > > On Tue, May 04, 2021 at 05:59:39PM +0200, Martin Kepplinger wrote:

[snip]

> I fixed mipi -> csi link. I had the DT port descriptions for mipi csi
> wrong.

\o/

> now, just because I think it makes sense, I do:
> 
> media-ctl --set-v4l2 "'csi':0 [fmt:SGBRG10/640x480 colorspace:raw]"
> 
> which now prints:
> 
> Device topology
> - entity 1: csi (2 pads, 2 links)
>             type V4L2 subdev subtype Unknown flags 0
>             device node name /dev/v4l-subdev0
> 	pad0: Sink
> 		[fmt:SGBRG10_1X10/640x480 field:none colorspace:raw xfer:none ycbcr:601 quantization:full-range]
> 		<- "imx8mq-mipi-csis.0":1 [ENABLED,IMMUTABLE]
> 	pad1: Source
> 		[fmt:SGBRG10_1X10/640x480 field:none colorspace:raw xfer:none ycbcr:601 quantization:full-range]
> 		-> "csi capture":0 [ENABLED,IMMUTABLE]
> 
> - entity 4: csi capture (1 pad, 1 link)
>             type Node subtype V4L flags 0
>             device node name /dev/video1
> 	pad0: Sink
> 		<- "csi":1 [ENABLED,IMMUTABLE]
> 
> - entity 10: imx8mq-mipi-csis.0 (2 pads, 2 links)
>              type V4L2 subdev subtype Unknown flags 0
>              device node name /dev/v4l-subdev1
> 	pad0: Sink
> 		<- "hi846 2-0020":0 []
> 	pad1: Source
> 		-> "csi":0 [ENABLED,IMMUTABLE]

This subdev doesn't seem to report formats on its sink and source pads,
which is weird. I've had a quick look at the .get_fmt() and .set_fmt()
implementations in the code you've posted, and they're wrong. They
shouldn't pass the calls to the source subdev with v4l2_subdev_call(),
they should instead implement get and set format on this subdev. You can
look at the imx7-mipi-csis driver to see how that's done. Once you'll
have fixed this, you'll have to set the format on each pad with
media-ctl to make sure formats through the pipeline match.

The only location where you imx8mq-mipi-csis driver should use
v4l2_subdev_call() is in .s_stream(), to propagate the operation to the
source.

By the way, I'd replace every occurence of "csis" with "csi2" in your
driver. The name "csis" in the i.MX7 driver comes from the CSI-2 RX IP
core that is named CSIS. That's not the case on the i.MX8QM.

> - entity 15: hi846 2-0020 (1 pad, 1 link)
>              type V4L2 subdev subtype Sensor flags 0
>              device node name /dev/v4l-subdev2
> 	pad0: Source
> 		[fmt:SGBRG10_1X10/640x480 field:none colorspace:raw]
> 		-> "imx8mq-mipi-csis.0":0 []

You need to enable this link, the following should do

media-ctl -l "'hi846 2-0020':0 -> 'imx8mq-mipi-csis.0':0 [1]"

> > > btw, my test is:
> > > 
> > > v4l2-ctl -d "/dev/v4l/by-path/platform-30a90000.csi1_bridge-video-index0"
> > > --set-fmt-video=width=640,height=480 --stream-mmap
> > > --stream-to=test.raw --stream-count=1
> > > 
> > > and that (probably because of the missing link) fails with
> > > 
> > > VIDIOC_STREAMON returned -1 (No such device)
> > > 
> > > which is in the kernel:
> > > 
> > > imx7-csi 30a90000.csi1_bridge: pipeline start failed with -19
> > 
> > Let's fix the missing link first.
> 
> But now when trying to stream a frame, the error is:
> 
> Because of:
> 
> media bus code not compatible with the pixel format set on the video
> node: 1 != 0
> 
> I get :
> 
> imx7-csi 30a90000.csi1_bridge: capture format not valid
> 
> which becomes for userspace:
> 
> VIDIOC_STREAMON returned -1 (Broken pipe)
> 
> Could that be a "user-problem" because "fmt" is not exactly the same
> everywhere? Also, the sensor entity pad is not yet ENABLED...

There's a combination of kernel-side issues (as detailed above) and
userspace issues (also as detailed above :-)).

> (media-ctl is still very new to me, sorry if that's dumb questions now)

It's not dumb at all.

-- 
Regards,

Laurent Pinchart