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Date:      Fri, 19 Jul 2019 23:54:21 -0600
From:      Sergey Manucharian <sm@ara-ler.com>
To:        Oleksandr Tymoshenko <gonzo@bluezbox.com>
Cc:        Vijay Kumar Banerjee <vijaykumar9597@gmail.com>, freebsd-arm@freebsd.org
Subject:   Re: Question regarding framebuffer driver.
Message-ID:  <20190720055421.GB41013@dendrobates>
In-Reply-To: <20190720024214.GA56812@bluezbox.com>
References:  <CAFgkNAnjbN5M5XSsNR=5EbGB%2BDjW1n4qM%2B1=QpdP3PueaSeUDQ@mail.gmail.com> <20190720024214.GA56812@bluezbox.com>

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Vijay Kumar Banerjee (vijaykumar9597@gmail.com) wrote:
> > >From the FreeBSD bootlog (12-RELEASE), I see that the screen is
> > turning on after the VT initialization message, so I guess it's something
> > that happens after the vt initialization that turns the screen on.

What kind of screen? If it's not HDMI, but directly connected LCD,
"turn on" has two different meaning: one is the screen's backlight,
another is the actual text/image drawn on the screen. So, even if your
screen is black, do you see the backlight? Usually the backlight is
controlled by PWM signal, if the backlight is off, the corresponding pin 
is not configured properly. Instead of PWM you can configure it just as 
output with high value to check.

Excerpts from Oleksandr Tymoshenko's message from Fri 19-Jul-19 19:42:
> without HDMI framer and try to initialize framebuffer in am335x_lcd
> driver with certain pattern to make sure it works. FreeBSD driver worked
> with 4DCAPE [1] at some point, so it might be a good start.

I confirm it works with Newhaven 7" LCD cape as well.
(Except touchpanel, which is completely different story).

-S.





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