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

[Adam Ford]

On Tue, Aug 2, 2022 at 3:08 AM Marco Felsch <m.felsch at pengutronix.de> wrote:
>
> Hi Adam, Fabio,
>
> On 22-08-01, Adam Ford wrote:
> > On Mon, Aug 1, 2022 at 8:53 PM Fabio Estevam <festevam at gmail.com> wrote:
> > >
> > > On Mon, Aug 1, 2022 at 10:39 PM Adam Ford <aford173 at gmail.com> wrote:
> > >
> > > > I managed to get my HDMI output working. I had the lanes set to 2
> > > > instead of 4.  Once I switched to 4-lanes, the monitor came up in
> > > > 1080p.  I haven't yet been able to get other modes to work.
> > >
> > > Ok, good. On another thread, you mentioned that you were also trying
> > > to get LVDS to work via SN65DSI83.
> > >
> > > Does LVDS work for you on this branch?
> >
> > I haven't tried with Marek's latest suggestion.  In the other thread
> > he mentioned a burst mode and setting the DSI speeds to higher
> > frequencies, but the patch he had didn't look like it would apply
> > cleanly, so I will need to dig into that a bit further.
>
> Can you provide me a link to this thread?

Sure,

https://www.spinics.net/lists/dri-devel/msg358301.html

>
> > Since my company doesn't really ship the LVDS displays with the kits,
> > the HDMI is the default video, so I've been focusing on it.
> >
> > To answer Marco's question, I was able to revert "MLK-21958-13:
> > drm/bridge: adv7511: Limit supported clocks" and still get a display
> > at 1080p, but all the other resolutions I tried appear to come up
> > blank.
>
> Cool so now you have the same state as we are.

I have a couple patches applied to mine which mimic some of the stuff
that NXP did.  Since I have access to a programmer manual, i was able
to confirm some of the 7535 specific stuff and the low-refresh rate
changes in their kernel appear appropriate and I also created a second
table of default settings for the 7535 and if the type is set
properly, i'll use the newer table instead of the older one. If anyone
wants any of these patches, I can certainly share them, but I am not
certain they make any difference.

There are a few other items in the programmer manual that I want to
attempt to implement once I have a chance to further review the
document.

>
> I think that the most important one is the blanking calc. Can you try to
> revert "drm/bridge: adv7511: Repair bus_flags and bus_format" and check
> if you can get a output still? Also something to try would be to disable
> the internal timing generator by specifying
> 'adi,disable-timing-generator'. Also if you have an oscilloscope for
> such frequencies you can check the hdmi clk-lane. I noticed that this is
> sometimes wrong.

I am doing this from my home office as a side project, so I don't have
a scope, but I can try to revert the other patch and try to disable
the internal timing generator when I get home tonight.  I'll report my
findings.

>
> Regards,
>   Marco
>
> > I didn't try every one.  With that revert, more options come
> > available, but 1440x900 and 800x600 were options I tried
> > unsuccessfullyl.
>
> >
> > adam
> >