On Wed, Aug 11, 2021 at 5:05 AM Rao G <grao.v80@gmail.com> 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 <nico.h@gmx.de> 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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