Date: Sat, 20 Jul 2019 17:03:25 +0530 From: Vijay Kumar Banerjee <vijaykumar9597@gmail.com> To: Sergey Manucharian <sm@ara-ler.com> Cc: Oleksandr Tymoshenko <gonzo@bluezbox.com>, freebsd-arm@freebsd.org Subject: Re: Question regarding framebuffer driver. Message-ID: <CAFgkNAkgv5NBVt95c0bhqAvC0Yw9JDbxXN970LWELme9bHkVZQ@mail.gmail.com> In-Reply-To: <20190720055421.GB41013@dendrobates> References: <CAFgkNAnjbN5M5XSsNR=5EbGB%2BDjW1n4qM%2B1=QpdP3PueaSeUDQ@mail.gmail.com> <20190720024214.GA56812@bluezbox.com> <20190720055421.GB41013@dendrobates>
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On Sat, Jul 20, 2019 at 11:24 AM Sergey Manucharian <sm@ara-ler.com> wrote: > 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. > > Hi, I'm using an HDMI screen and by turn on I mean that there's no backlight. In case of HDMI what is responsible for turning on the backlight? I can see the EDID reading working and the values match the ones I get from the FBSD image, which means the TDA driver is working I suppose (?) Regarding PWM : From the device tree obtained form the FreeBSD tree, I see that the PWM entries are "disabled" and during the startup I can see that they're not attaching because the ofw_bus_status_okay fails. Is it supposed to be manually set to "okay" with an overlay or something is going wrong in the pwm driver? > 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). > > If there's no other clue I can follow this way of stepwise checking each drivers. Can you please elaborate "hardcoding logic in TDA so it doesn't require VT"? I'm new to the FreeBSD source so any hint is much appreciated. Thanks for the quick reply and for the helpful tips. Best Regards, Viay > -S. > > >
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