linux-kernel - Re: [PATCH REPOST] TDA1997x: replace video detection routine

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Date:   Fri, 23 Jul 2021 13:57:06 +0200
From:   Krzysztof Hałasa <khalasa@...p.pl>
To:     Hans Verkuil <hverkuil@...all.nl>
Cc:     Tim Harvey <tharvey@...eworks.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        linux-media@...r.kernel.org, lkml <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH REPOST] TDA1997x: replace video detection routine

Hi Hans,

Hans Verkuil <hverkuil@...all.nl> writes:

> The tda1997x doesn't have any method of obtaining the sync polarities?
>
> HSync and VSync are, as you say, using in-band signaling, but the 'polarity'
> still matters when it comes to detecting timings. All HDMI receivers I have
> ever seen have a register that reports the polarities. I find it *very* hard
> to imagine that this device doesn't support that.

I didn't know that HDMI serializers send the logical levels of those
lines, I thought some frame/field/line start/end codes are sent instead.
I will have to have a closer look at this chip, then.

> Do you have a datasheet for this device?

No, there is only the current driver and also the old one (in Gateworks'
Freescale/NXP kernel). Tim may have something perhaps under NDA, maaybe.

I will see if I can find these bits in the registers.

Thanks.
-- 
Krzysztof "Chris" Hałasa

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