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Date:   Wed, 3 Aug 2022 07:56:02 +0200
From:   Marco Felsch <m.felsch@pengutronix.de>
To:     Adam Ford <aford173@gmail.com>
Cc:     Fabio Estevam <festevam@gmail.com>, Marek Vasut <marex@denx.de>,
        Stefan Agner <stefan@agner.ch>,
        Jernej Skrabec <jernej.skrabec@gmail.com>,
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        David Airlie <airlied@linux.ie>,
        dri-devel <dri-devel@lists.freedesktop.org>,
        Neil Armstrong <narmstrong@baylibre.com>,
        NXP Linux Team <linux-imx@nxp.com>,
        Robert Foss <robert.foss@linaro.org>,
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        laurentiu.palcu@nxp.com
Subject: Re: imx8mm lcdif->dsi->adv7535 no video, no errors
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Hi Adam,

sorry for the delay.

On 22-08-02, Adam Ford wrote:

...

> > > 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
> 
> I did some reading about the internal timing generator.  It appears
> that it's required when video formats use fractional bytes, and it's
> preconfigured to run at 720p by default, but registers 28h through 37h
> configure it for other video modes.

I thought this timing generator can detect the sync timing
automatically. Also I saw some mail discussions where this timing
generator can trigger missbehaviours. Since we send the sync packages
from the dsi-host to the ADV, I think it should be possible for the ADV
to reconstruct the sync signals without the need of the internal timing
generator.

> Are you thinking the imx8mm DSI generator would do it better?

You mean the porches we are sending?

Regards,
  Marco