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Message-ID: <20220804095715.d3ay7yvn2adxdo4x@pengutronix.de>
Date: Thu, 4 Aug 2022 11:57:15 +0200
From: Marco Felsch <m.felsch@...gutronix.de>
To: Adam Ford <aford173@...il.com>
Cc: Dave Stevenson <dave.stevenson@...pberrypi.com>,
Neil Armstrong <narmstrong@...libre.com>,
David Airlie <airlied@...ux.ie>,
dri-devel <dri-devel@...ts.freedesktop.org>,
Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
Andrzej Hajda <andrzej.hajda@...el.com>,
Marek Szyprowski <m.szyprowski@...sung.com>,
Marek Vasut <marex@...x.de>,
Jernej Skrabec <jernej.skrabec@...il.com>,
Jagan Teki <jagan@...rulasolutions.com>, robert.chiras@....com,
laurentiu.palcu@....com, NXP Linux Team <linux-imx@....com>,
Jonas Karlman <jonas@...boo.se>,
Sascha Hauer <s.hauer@...gutronix.de>,
arm-soc <linux-arm-kernel@...ts.infradead.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Robert Foss <robert.foss@...aro.org>,
Pengutronix Kernel Team <kernel@...gutronix.de>,
Shawn Guo <shawnguo@...nel.org>
Subject: Re: imx8mm lcdif->dsi->adv7535 no video, no errors
On 22-08-03, Adam Ford wrote:
> On Wed, Aug 3, 2022 at 7:17 AM Dave Stevenson
...
> > Not meaning to butt in, but I have datasheets for ADV7533 and 7535
> > from previously looking at these chips.
>
> Thanks for the feedback.
>
> > Mine fairly plainly states:
> > "The DSI receiver input supports DSI video mode operation only, and
> > specifically, only supports nonburst mode with sync pulses".
> > Non-burst mode meaning that the DSI pixel rate MUST be the same as the
> > HDMI pixel rate.
>
> Mine also states the DSI source needs to provide correct video timing
> with start and stop sync packets.
>
> If I remember correctly, it seemed like Marek V wanted the hard coded
> samsung,burst-clock-frequency to go away so the clock frequency could
> be set dynamically.
As previously said, this is something on our TODO list too :) but needs
a bit more infrastructure work.
> I have attempted to do some of this work based on what I am seeing in
> the NXP kernel, and I get get my monitor to sync at some resolutions,
> but the screen is usually all green or all blue, so it's not really a
> success. The clock part appears to be good enough to make the monitor
> see some sort of signal, so I am going to investigate the calculation
> of the rest of the video timings to see if I can fix the color issue.
Please don't pay to much attention to the NXP kernel. No one have a glue
where those porches came from. If I specify the burst-clock-freq. to
445.5 and set the lane number to 4 and hack in the porches values from
NXP, than I get a 720P output too. But this isn't the way to go instead
we should calc the porches settings and the burst-clock-frequency
dynamiclly to provide more than just a few resolutions. But for that we
need a clear understanding of how the ADV is working.
I will prepare a repo to day and will send you a link with the hack
patches in it, so you can test it :)
Regards,
Marco
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