Re: [RFC V2 0/5] arm64: dts: imx8mm: Enable CSI and OV5640 Camera

[Laurent Pinchart]

Hi Adam,

On Wed, Oct 27, 2021 at 07:39:40PM -0500, Adam Ford wrote:
> On Sun, Oct 24, 2021 at 7:16 AM Fabio Estevam wrote:
> >
> > Hi Adam,
> >
> > [Adding Frieder on Cc]
> >
> > On Sat, Oct 23, 2021 at 5:35 PM Adam Ford <aford173@xxxxxxxxx> wrote:
> > >
> > > The imx8mm appears to have both a CSI bridge and mipi-csi-2 drivers.  With
> > > those enabled, both the imx8mm-evk and imx8mm-beacon boards should be able
> > > use an OV5640 camera.
> > >
> > > The mipi-csi2 driver sets the clock frequency to 333MHz, so the clock parent
> > > of the CSI1 must be reparented to a faster clock.  On the custom NXP kernel,
> > > they use IMX8MM_SYS_PLL2_1000M, so that is done in the device tree to match.
> > >
> > > With the CSI and mipi_csi2 drivers pointing to an OV5640 camera, the media
> > > pipeline can be configured with the following:
> > >
> > >     media-ctl --links "'ov5640 1-003c':0->'imx7-mipi-csis.0':0[1]"
> > >
> > > The camera and various nodes in the pipeline can be configured for UYVY:
> > >     media-ctl -v -V "'ov5640 1-003c':0 [fmt:UYVY8_1X16/640x480 field:none]"
> > >     media-ctl -v -V "'csi':0 [fmt:UYVY8_1X16/640x480 field:none]"
> > >
> > > With that, the media pipeline looks like:
> > >
> > >
> > > Media controller API version 5.15.0
> > >
> > > Media device information
> > > ------------------------
> > > driver          imx7-csi
> > > model           imx-media
> > > serial
> > > bus info        platform:32e20000.csi
> > > hw revision     0x0
> > > driver version  5.15.0
> > >
> > > 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:UYVY8_1X16/640x480 field:none colorspace:srgb xfer:srgb ycbcr:601 quantization:lim-range]
> > >                 <- "imx7-mipi-csis.0":1 [ENABLED,IMMUTABLE]
> > >         pad1: Source
> > >                 [fmt:UYVY8_1X16/640x480 field:none colorspace:srgb xfer:srgb ycbcr:601 quantization:lim-range]
> > >                 -> "csi capture":0 [ENABLED,IMMUTABLE]
> > >
> > > - entity 4: csi capture (1 pad, 1 link)
> > >             type Node subtype V4L flags 0
> > >             device node name /dev/video0
> > >         pad0: Sink
> > >                 <- "csi":1 [ENABLED,IMMUTABLE]
> > >
> > > - entity 10: imx7-mipi-csis.0 (2 pads, 2 links)
> > >              type V4L2 subdev subtype Unknown flags 0
> > >              device node name /dev/v4l-subdev1
> > >         pad0: Sink
> > >                 [fmt:UYVY8_1X16/640x480 field:none colorspace:smpte170m xfer:709 ycbcr:601 quantization:lim-range]
> > >                 <- "ov5640 1-003c":0 [ENABLED]
> > >         pad1: Source
> > >                 [fmt:UYVY8_1X16/640x480 field:none colorspace:smpte170m xfer:709 ycbcr:601 quantization:lim-range]
> > >                 -> "csi":0 [ENABLED,IMMUTABLE]
> > >
> > > - entity 15: ov5640 1-003c (1 pad, 1 link)
> > >              type V4L2 subdev subtype Sensor flags 0
> > >              device node name /dev/v4l-subdev2
> > >         pad0: Source
> > >                 [fmt:UYVY8_1X16/640x480@1/30 field:none colorspace:srgb xfer:srgb ycbcr:601 quantization:full-range]
> > >                 -> "imx7-mipi-csis.0":0 [ENABLED]
> > >
> > > When configured, gstreamer can be used to capture 1 frame and store it to a file.
> > >
> > > gst-launch-1.0 -v v4l2src num-buffers=1 ! video/x-raw,format=UYVY,width=640,height=480,framerate=60/1 ! filesink location=test
> > >
> > > Unfortunately, the video capture never appears to happen.  No errors occur, not
> > > interrupts are recorded and no errors are recorded.
> > >
> > > gst-launch-1.0 -v v4l2src num-buffers=1 ! video/x-raw,format=UYVY,width=640,height=480,framerate=60/1 ! filesink location=test
> > > Setting pipeline to PAUSED ...
> > > Pipeline is live and does not need PREROLL ...
> > > Pipeline is PREROLLED ...
> > > Setting pipeline to [  114.819632] v4l2_get_link_freq: Link frequency estimated using pixel rate: result might be inaccurate
> > > PLAYING ...
> > > New clock: GstSystem[  114.829203] v4l2_get_link_freq: Consider implementing support for V4L2_CID_LINK_FREQ in the transmitter driver
> > > Clock
> > > /GstPipeline:pipeline0/GstV4l2Src:v4l2src0.GstPad:src: caps = video/x-raw, format=(string)UYVY, width=(int)640, height=(int)480, framerate=(fraction)60/1, interlace-mode=(string)progressive, colorimetry=(string)bt709
> > > /GstPipeline:pipeline0/GstCapsFilter:capsfilter0.GstPad:src: caps = video/x-raw, format=(string)UYVY, width=(int)640, height=(int)480, framerate=(fraction)60/1, interlace-mode=(string)progressive, colorimetry=(string)bt709
> > > /GstPipeline:pipeline0/GstFileSink:filesink0.GstPad:sink: caps = video/x-raw, format=(string)UYVY, width=(int)640, height=(int)480, framerate=(fraction)60/1, interlace-mode=(string)progressive, colorimetry=(string)bt709
> > > /GstPipeline:pipeline0/GstCapsFilter:capsfilter0.GstPad:sink: caps = video/x-raw, format=(string)UYVY, width=(int)640, height=(int)480, framerate=(fraction)60/1, interlace-mode=(string)progressive, colorimetry=(string)bt709
> > >
> > >
> > > If anyone has any insight as to what might be wrong, I'd like feedback.
> > > I posted a device tree that I beleive goes with the newer imx8mm-evk, but
> > > I do not have this hardware, so I cannot test it.
> >
> > It seems that Frieder on Cc managed to get camera capture to work on
> > i.MX8MM here:
> > https://git.kontron-electronics.de/sw/misc/linux/-/commits/v5.10-mx8mm-csi
> >
> > Hopefully, this can help to figure out what is missing in mainline to
> > get camera capture to work on i.MX8M.
> >
> > I don't have access to an OV5640 camera to connect to the imx8mm-evk
> > board to try your series.
> 
> Fabio,
> 
> Thanks for the heads up on that repo.  I was able to use that repo and
> get still images to capture on an OV5640, but I noticed a fair amount
> of differences between that repo and what's found in linux-next.
> 
> Laurent,
> 
> I haven't exhausted the patch differences, but I found at least a few
> that appear to be missiing upstream, and I am curious to know if/what
> your opinion is on whether or not they're needed, since the patches on
> Frieder's repo appear to come from you.
> [1] - media: imx: imx7-media-csi: Add i.MX8MM identification

This shouldn't make any difference.

> [2] - media: imx: imx7_mipi_csis: Don't set reserved CLK_CTRL field on i.MX8MM

This was based on my analysis of the reference manual, but it turned out
to be incorrect, the i.MX8MM CSI-2 receiver didn't work at all for me
with that patch.

> [3] - media: imx: imx7_mipi_csis: Set dual pixel mode for RAW formats

This one isn't clear to me yet. I'll have to retest, I think I had to
set dual pixel mode to capture RAW8 and RAW10 with the OV5640, but
setting it broke raw capture with a different sensor. More investigation
is needed. In any case, with or without that patch, you should get
interrupts from the CSIS as the dual pixel mode is related to the
interface with the CSI bridge.

> media: imx: imx7_mipi_csis: Set dual pixel mode for RAW formats
> 
> Maybe these don't need to be applied, but they are 'some' of the
> differences that I see between this 5.10 branch and linux-next .  I
> know there are more, but
> 
> 
> [1] - https://git.kontron-electronics.de/sw/misc/linux/-/commit/8ac7ec6db0c260a871038721886dbdb6660ed84c
> [2] - https://git.kontron-electronics.de/sw/misc/linux/-/commit/0b5727c8eba8c370f7db5eace0243f78992a4dbb
> [3] - https://git.kontron-electronics.de/sw/misc/linux/-/commit/14befa6bc146b10092a6ac5d0ed4d42c87c6cf27
> 
> Frieder et al,
> 
> Have you (or anyone) tried CSI cameras on anything newer than 5.10?  I
> am curious to see if a regression popped in somewhere, but git bisect
> will make this difficult since there is a fair amount of variation
> between this custom repo and the upstream.

I'll try to run tests on mainline again, but it will have to wait a
couple of weeks I'm afraid.

-- 
Regards,

Laurent Pinchart