imx8mm lcdif->dsi->adv7535 no video, no errors

[Adam Ford]

On Mon, Aug 1, 2022 at 3:07 PM Adam Ford <aford173 at gmail.com> wrote:
>
> On Mon, Aug 1, 2022 at 2:33 PM Fabio Estevam <festevam at gmail.com> wrote:
> >
> > Hi Adam,
> >
> > On Sat, Jul 30, 2022 at 12:16 PM Adam Ford <aford173 at gmail.com> wrote:
> > >
> > > Hey all,
> > >
> > > I am trying to test Jagan's patch series [1] to add support for the
> > > samsung dsim bridge which is used on the imx8mm to output DSI video.
> > > The DSIM gets the video from the mxsfb, and in my case, the DSI is
> > > sent to the adv7535 for connecting to HDMI.
> >
> > I had to add some extra patches on top of Jagan's imx8mm-dsi-v3 to get
> > HDMI output functional on a imx8mm-evk via ADV7535:
> >
> > https://github.com/fabioestevam/kernel/commits/imx8mm-dsi-v3
> >
> > Does it work on your board?

Fabio,

I tried your branch, but I still get no video on the output of HDMI.
I do get a response to the modetest.  I won't post the whole thing
here, but here is a snippet

CRTCs:
id fb pos size
33 37 (0,0) (1920x1080)
  #0 1920x1080 60.00 1920 2008 2052 2200 1080 1084 1089 1125 148500
flags: nhsync, nvsync; type: driver
  props:
24 VRR_ENABLED:
flags: range
values: 0 1
value: 0

Planes:
id crtc fb CRTC x,y x,y gamma size possible crtcs
31 33 37 0,0 0,0 0        0x00000001
  formats: RG16 XR24
  props:
8 type:
flags: immutable enum
enums: Overlay=0 Primary=1 Cursor=2
value: 1
30 IN_FORMATS:
flags: immutable blob
blobs:

value:
01000000000000000200000018000000
01000000200000005247313658523234
03000000000000000000000000000000
0000000000000000
in_formats blob decoded:
RG16:  LINEAR
XR24:  LINEAR

Frame buffers:
id size pitch

When I compare this with NXP's downstream kernel that works with this
monitor, I get some different info:

CRTCs:
id fb pos size
33 41 (0,0) (1920x1080)
  #0 1920x1080 60.00 1920 2008 2052 2200 1080 1084 1089 1125 148500
flags: nhsync, nvsync; type: driver
  props:
24 VRR_ENABLED:
flags: range
values: 0 1
value: 0

Planes:
id crtc fb CRTC x,y x,y gamma size possible crtcs
31 33 41 0,0 0,0 0        0x00000001
  formats: XR24 AR24 RG16 XB24 AB24 RX24 RA24 AR15 XR15 AB15 XB15 BG16
  props:
8 type:
flags: immutable enum
enums: Overlay=0 Primary=1 Cursor=2
value: 1
32 zpos:
flags: immutable range
values: 0 0
value: 0

Frame buffers:
id size pitch

Notably, the  formats for the downstream list significantly more
formats.  I don't know how that translates to working video, but it
was something to note.

>
> I'll give them a try tonight.  I managed to get a hold of an adv7535
> user manual, and there are some items that it appears NXP did in their
> downstream kernel that never got pushed upstream. Based on my review
> of some of the changes, some of the NXP changes seem reasonable to me.
> If/when I can get it working, I'll try to report back some of my
> findings and push driver changes to the adv7535 as I find them.
>
> adam