Re: [PATCH v12 00/18] drm: Add Samsung MIPI DSIM bridge

Adam Ford
2023-02-24T15:01:59Z

On Fri, Feb 24, 2023 at 8:08 AM Rasmus Villemoes
<rasmus.villemoes@prevas.dk> wrote:
>
> On 22/02/2023 11.05, Frieder Schrempf wrote:
>
> > The NXP kernel is completely different. AFAIK it uses the component
> > helpers to bundle all subdrivers from a central driver
> > (display-subsystem). This is not how the mainline approach using the
> > bridge driver interface works. So you can't compare them.
> >
> > Did you look at this extensive thread with findings from Adam?
> >
> > https://lore.kernel.org/lkml/CAHCN7xJ=N1vWVTBjArskJ59fyaLzmAGWfc0E=_iGizrDNR_Udw@mail.gmail.com/
> >
> > It is related to HDMI, but I guess a lot of things are valid for DP, too.
> >
> > Anyway, we need to get this series merged. Otherwise we can't work on
> > fixing all the other issues on top.
>
> Alright, I finally managed to get the imx8mm-dsi-v12 branch (commit
> fdde97c7d553) to work, by modifying Marek's patch for enabling the
> lcdif->mipi pipeline a little. The end result is in
> https://github.com/Villemoes/linux/tree/imx8mp-mipi . There are also a
> few cherry-picks of by-now-upstream patches to imx8mp.dtsi included.
>
> It works on our custom hardware, with the ti,sn65dsi86 mipi->eDP bridge.
>
> It does not seem to work on the imx8mp-evk with the adv7535 hdmi bridge
> daughter board, but that's probably just as much the fault of the
> adv7535 driver as anything in the SOC - it's impossible to get a real
> data sheet for that thing, and there's no end of random patches floating
> around, with the NXP kernel doing completely their own thing. So I've
> given up on getting that to work.

I have a board with an ADV7535, and for that chip to work, there needs
to be some work to do some math on the front porch, back port, and
sync timings based on the number of lanes. I have a work-in-progress
which supports 1080p, but I was waiting for the series to get accepted
first, since it seems to work when interacting directly with DSI
displays. I have my patch working on imx8mm, imx8mn and imx8mp. Once
the base driver is accepted, I'll push the patch for review.

adam

>
> Rasmus