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

[Thomas Zimmermann <tzimmermann@suse.de>]

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Hi

Am 21.04.22 um 19:39 schrieb James Hilliard:
> On Thu, Apr 21, 2022 at 8:22 AM Javier Martinez Canillas
> <javierm@redhat.com> wrote:
>>
>> On 4/21/22 14:54, Patrik Jakobsson wrote:
>>> On Thu, Apr 21, 2022 at 2:47 PM Javier Martinez Canillas
>>> <javierm@redhat.com> 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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