linux-kernel - Re: [PATCH v3] drm/gma500: depend on framebuffer

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Date:   Mon, 11 Apr 2022 11:27:43 +0200
From:   Patrik Jakobsson <patrik.r.jakobsson@...il.com>
To:     James Hilliard <james.hilliard1@...il.com>
Cc:     dri-devel <dri-devel@...ts.freedesktop.org>,
        Randy Dunlap <rdunlap@...radead.org>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3] drm/gma500: depend on framebuffer

On Sun, Apr 10, 2022 at 10:05 PM James Hilliard
<james.hilliard1@...il.com> wrote:
>
> On Sun, Apr 10, 2022 at 1:52 PM Patrik Jakobsson
> <patrik.r.jakobsson@...il.com> wrote:
> >
> > On Sun, Apr 10, 2022 at 9:40 PM James Hilliard
> > <james.hilliard1@...il.com> wrote:
> > >
> > > On Sun, Apr 10, 2022 at 1:36 PM Patrik Jakobsson
> > > <patrik.r.jakobsson@...il.com> wrote:
> > > >
> > > > On Sat, Apr 9, 2022 at 6:23 AM James Hilliard <james.hilliard1@...il.com> wrote:
> > > > >
> > > > > Select the efi framebuffer if efi is enabled.
> > > > >
> > > > > This appears to be needed for video output to function correctly.
> > > > >
> > > > > Signed-off-by: James Hilliard <james.hilliard1@...il.com>
> > > >
> > > > Hi James,
> > > > EFI_FB is its own driver and not needed by gma500 to drive its
> > > > hardware. What makes you think it's required?
> > >
> > > I wasn't getting any HDMI video output without it enabled for some reason,
> > > I assume it is doing some sort of initialization needed by gma500
> > > during startup.
> >
> > Then it sounds like you might just be using EFI_FB and not gma500. Can
> > you provide the kernel log with drm.debug=0x1f set on kernel
> > command-line.
>
> Seems efifb loads first and then hands off to gma500

That is how it normally works but efifb shouldn't change the state of
the currently set mode so shouldn't affect gma500.
>From the logs I can see that you have LVDS (internal panel), HDMI and
DP (3 displays in total) connected. This sounds wrong. Your version of
gma500 (Cedarview) doesn't support more than 2 crtcs/pipes. This might
be a problem.