Re: [PATCH 3/3] drm/vkms: fbdev emulation support

From: Daniel Vetter <daniel@ffwll.ch>
To: Neil Armstrong <narmstrong@baylibre.com>
Cc: Haneen Mohammed <hamohammed.sa@gmail.com>,
	Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com>,
	Daniel Vetter <daniel.vetter@ffwll.ch>,
	DRI Development <dri-devel@lists.freedesktop.org>,
	Melissa Wen <melissa.srw@gmail.com>,
	Thomas Zimmermann <tzimmermann@suse.de>,
	Daniel Vetter <daniel.vetter@intel.com>
Subject: Re: [PATCH 3/3] drm/vkms: fbdev emulation support
Date: Mon, 12 Oct 2020 16:23:35 +0200	[thread overview]
Message-ID: <20201012142335.GY438822@phenom.ffwll.local> (raw)
In-Reply-To: <9ad2c6dd-9f3e-8b88-e013-dcb0e1fd8005@baylibre.com>

On Mon, Oct 12, 2020 at 02:40:58PM +0200, Neil Armstrong wrote:
> Hi,
> 
> On 12/10/2020 13:24, Thomas Zimmermann wrote:
> > Hi
> > 
> > On Sat, 10 Oct 2020 01:21:56 +0200 Daniel Vetter <daniel.vetter@ffwll.ch>
> > wrote:
> > 
> >> Hooray for generic fbdev support, making this a oneliner. We just
> >> needed to fix preferred_depth fixed and the vmap support added first.
> >>
> >> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
> >> Cc: Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com>
> >> Cc: Melissa Wen <melissa.srw@gmail.com>
> >> Cc: Haneen Mohammed <hamohammed.sa@gmail.com>
> >> Cc: Daniel Vetter <daniel@ffwll.ch>
> >> ---
> >>  drivers/gpu/drm/vkms/vkms_drv.c | 2 ++
> >>  1 file changed, 2 insertions(+)
> >>
> >> diff --git a/drivers/gpu/drm/vkms/vkms_drv.c b/drivers/gpu/drm/vkms/vkms_drv.c
> >> index 6221e5040264..cc09e2df5cb1 100644
> >> --- a/drivers/gpu/drm/vkms/vkms_drv.c
> >> +++ b/drivers/gpu/drm/vkms/vkms_drv.c
> >> @@ -169,6 +169,8 @@ static int __init vkms_init(void)
> >>  	if (ret)
> >>  		goto out_devres;
> >>  
> >> +	drm_fbdev_generic_setup(&vkms_device->drm, 0);
> >> +
> > 
> > It feels strange to have console support in a driver for non-interactive
> > systems. But OK, why not. I guess it helps with testing?

Yeah I want to polish the igt fbdev testcase a bit, need a victim for fb
device selction. vkms was the quickest way to get two fbdev instances into
one box :-)

Plus more code we could test using igt & vkms in gitlab CI, whenever we
get around to that ...

> It's weird because it the kernel is misconfigured and no console is specified on the cmdline
> this console could become the main console...
> 
> It's a great feature, but couldn't this be a module parameter ?

If you have vkms enabled in a distro, you're doing it wrong.

Also, if you accidentally load vkms, then Xorg will happily bind to it
(maybe in preference to the real fbdev driver that's there as a simplefb).
So imo this problem isn't really new.
-Daniel

> 
> Neil
> 
> > 
> > Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
> > 
> > Best regards
> > Thomas
> > 
> >>  	return 0;
> >>  
> >>  out_devres:
> > 
> > _______________________________________________
> > dri-devel mailing list
> > dri-devel@lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/dri-devel
> > 
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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