[coreboot] Re: Question On External Display

[Rao G]

Hi Matt,

Compared VBT data in pre-OS and OS, the data is identical.

Likely issue due to MMIO registers not configured correctly defined in
below spec?
https://01.org/sites/default/files/documentation/intel_os_gfx_prm_vol10_-_di...

The LVDS display which is on DDI0 is fine so I could switch to OS and get
VBT data.
DP/HDMI/DVI on DDI1 in windows is causing the issue.

I expect coreboot is filling below mailbox's correctly?

INTEL_IGD_OPREGION_MBOX1  MBox1; // Mailbox 1: Public ACPI Methods
INTEL_IGD_OPREGION_MBOX2  MBox2; // Mailbox 2: Software SCI Inteface
INTEL_IGD_OPREGION_MBOX3  MBox3; // Mailbox 3: BIOS/Driver Communication
INTEL_IGD_OPREGION_VBT    VBT;   // Video BIOS Table (OEM customizable data)

Regards
Rao

On Thu, Aug 12, 2021 at 10:24 AM Rao G  wrote:
> Thank you Matt.
>
> the VBT data in BIOS and VBT data captured in OS if they remain identical
> would that mean this problem
> is not due to VBT data copied into ACPINVS igd_opregion?
>
> Attaching VBT data for this platform which is captured from OS
>
> also Xrandr output on each Video Interface
>
> On Wed, Aug 11, 2021 at 3:28 PM Matt DeVillier 
> wrote:
> > On Wed, Aug 11, 2021 at 5:05 AM Rao G  wrote:
> > > Thanks Nico for your response.
> > > > am expecting some register should set with eDP as interface and when
> > > > display is connected
> > > >
> > > > any clue why the i915 OS driver was turning off DP display in case 2?
> > >
> > > I assume the HPD signal doesn't get through to the software.
> > >
> > > [Rao]
> > > You mean I need to check PORT_HOTPLUG_EN and PORT_HOTPLUG_STAT mmio
> >
> > offsets for this issue?
> > > BIOS display is fine, Windows logo is also seen but there is no signal
> >
> > when "windows login" is reached
> >
> > IME, that's almost always due to incorrect/missing/mismatched VBT data
> > in the ACPI opregion/mailbox
> > > It had similar behaviour w.r.t to ubuntu 18.04, I configured DDI1 to
> >
> > "DP with HDMI/DVI"
> > > Can this issue be fixed with VBE data configured through BMP or it
> >
> > needs a fix from graphics MMIO?
> > > Regards
> > > Rao
> > >
> > > On Fri, Jul 30, 2021 at 10:27 PM Nico Huber  wrote:
> > > > On 30.07.21 18:59, Rao G wrote:
> > > > > Thanks Nico.
> > > > >
> > > > > HPD is active , measured the signal
> > > >
> > > > Is your coreboot port public somewhere? If the hardware is fine, maybe
> > > > the firmware isn't?
> > > > > Configured Ports
> > > > > 1.DDI0- PortB - DP with HDMI/DVI is good in BIOS & OS
> > > > > 2.DDI1- PortC - DP with HDMI/DVI is good in BIOS, i915 was turning
> >
> > off the
> > > > > DP display (Never understood the reason)
> > > >
> > > > It's very suspicious that these two behave differently. Does the HPD
> > > > signal (MMIO read) work for DDI0?
> > > > > So configured PortC with eDP
> > > > >
> > > > > If there is no way BIOS to detect the external display with MMIO
> >
> > registers
> > > > > when configured as eDP, Can i not turn off the DDI1/Port C at
> >
> > runtime in
> > > > > BIOS,
> > > >
> > > > Maybe it's time to switch to an open-source solution? libgfxinit will
> > > > probably have the same issue, but it might be possible to get a rather
> > > > short delay.
> > > > > am expecting some register should set with eDP as interface and when
> > > > > display is connected
> > > > >
> > > > > any clue why the i915 OS driver was turning off DP display in case 2?
> > > >
> > > > I assume the HPD signal doesn't get through to the software.
> > > >
> > > > Nico
> > >
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