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

[Thomas Zimmermann <tzimmermann@xxxxxxx>]

Hi

Am 21.04.22 um 19:39 schrieb James Hilliard:
> On Thu, Apr 21, 2022 at 8:22 AM Javier Martinez Canillas
> <javierm@xxxxxxxxxx> wrote:
> > On 4/21/22 14:54, Patrik Jakobsson wrote:
> > > On Thu, Apr 21, 2022 at 2:47 PM Javier Martinez Canillas
> > > <javierm@xxxxxxxxxx> wrote:
> >
> > [snip]
> >
> > > > > > > diff --git a/drivers/gpu/drm/gma500/Kconfig b/drivers/gpu/drm/gma500/Kconfig
> > > > > > > index 0cff20265f97..a422fa84d53b 100644
> > > > > > > --- a/drivers/gpu/drm/gma500/Kconfig
> > > > > > > +++ b/drivers/gpu/drm/gma500/Kconfig
> > > > > > > @@ -2,11 +2,13 @@
> > > > > > >    config DRM_GMA500
> > > > > > >        tristate "Intel GMA500/600/3600/3650 KMS Framebuffer"
> > > > > > >        depends on DRM && PCI && X86 && MMU
> > > > > > > +     depends on FB
> > > > > >
> > > > > > Why do we need FB here? Framebuffer support should be hidden by DRM's
> > > > > > fbdev helpers.
> > > > >
> > > > > It is not needed but gives him video output since it enables the drm
> > > > > fbdev emulation.
> > > >
> > > > I'm not sure to understand this. Shouldn't depend on DRM_FBDEV_EMULATION then?
> > >
> > > No, it shouldn't depend on any FBDEV stuff since it's not actually
> > > required. It just happens to help in this case since weston + fbdev
> > > backend works but not weston with drm backend (or whatever config
> > > James have set).
> >
> > I see. Then the correct approach for them would be to just enable CONFIG_FB
> > and DRM_FBDEV_EMULATION in their kernel config, rather than making this to
> > depend on anything FB related as you said.
>
> Yeah, so it looks like CONFIG_FB_EFI is not needed but
> CONFIG_DRM_FBDEV_EMULATION is, I think I just assumed efifb
> was what was needed based on the kernel logs.
>
> This does not work:
> CONFIG_FB enabled
> CONFIG_DRM_FBDEV_EMULATION disabled
>
> This works:
> CONFIG_FB enabled
> CONFIG_DRM_FBDEV_EMULATION enabled
>
> > > > > I looked some more at the logs and it seems weston doesn't work on his
> > > > > system without the fbdev backend. So the question is why weston isn't
> > > > > working without fbdev? Perhaps this is just a Weston configuration
> > > > > issue?
> > > >
> > > > But is weston using the fbdev emulated by DRM or the one registered by
> > > > efifb? I thought that the latter from what was mentioned in this thread.
> > >
> > > It's using drm fbdev emulation with gma500 so EFIFB has nothing to do
> > > with this. I believe it was just simply incorrectly reported. If I'm
> > > correct then "depends on FB" is what makes video output work for
> > > James.
> >
> > Got it. Thanks for the clarification.
>
> Here's my weston.ini:
> [core]
> shell=kiosk-shell.so
> modules=systemd-notify.so
> backend=drm-backend.so
> idle-time=0
> require-input=false
> use-pixman=true
>
> [shell]
> locking=false
> cursor-theme=Obsidian
> panel-position=none
>
> [output]
> name=DVI-D-1
> transform=rotate-270
>
> [output]
> name=DP-2
> mode=off
>
> [output]
> name=LVDS-1
> mode=off

You mentioned that you want to use HDMI, but it's not configured here. 
Is that intentionally?

Best regards
Thomas

> [libinput]
> touchscreen_calibrator=true
>
> > --
> > Best regards,
> >
> > Javier Martinez Canillas
> > Linux Engineering
> > Red Hat

--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Ivo Totev

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