Re: [PATCH] simpldrm: Enable boot time VESA graphic mode selection.

[Thomas Zimmermann]

Hi

Am 18.02.22 um 11:08 schrieb Michal Suchánek:
> Hello,
>
> On Fri, Feb 18, 2022 at 10:57:33AM +0100, Thomas Zimmermann wrote:
> > Hi Michal
> >
> > Am 18.02.22 um 10:33 schrieb Michal Suchanek:
> > > Since switch to simpledrm VESA graphic modes are no longer available
> > > with legacy BIOS.
> > >
> > > The x86 realmode boot code enables the VESA graphic modes when option
> > > FB_BOOT_VESA_SUPPORT is enabled.
> > >
> > > To enable use of VESA modes with simpledrm in legacy BIOS boot mode drop
> > > dependency of BOOT_VESA_SUPPORT on FB, also drop the FB_ prefix, and
> > > select the option when simpledrm is built-in on x86.
> >
> > Thanks for sending the patch.
> >
> > I tested simpledrm on a VESA-based systems and it work. Do you have a
>
> In EFI or legacy mode?

It was a 32-bit AthlonXP. So as legacy as it gets.

> > concrete example of a mode that doesn't work any longer?
>
> As per discussion in
> https://bugzilla.opensuse.org/show_bug.cgi?id=1193250 vga=791 does not.

I wonder if this fixes a few more of the complains we've seen about 
missing resolutions.

> Also it is clear examinig the realmode code that this option is needed
> to enable graphic mode selection.
>
> I don't have a system with legacy BIOS at hand but from user testing
> this improves the situation - kernel does not reeject the videomode
> argument, and simpledrm is initialized during boot.

No doubt about that.

Best regards
Thomas

> Thanks
>
> Michal
>
> > > Fixes: 11e8f5fd223b ("drm: Add simpledrm driver")
> > > Signed-off-by: Michal Suchanek <msuchanek@xxxxxxx>
> > > ---
> > >    arch/x86/boot/video-vesa.c   | 4 ++--
> > >    drivers/gpu/drm/tiny/Kconfig | 1 +
> > >    drivers/video/fbdev/Kconfig  | 9 ++++-----
> > >    3 files changed, 7 insertions(+), 7 deletions(-)
> > >
> > > diff --git a/arch/x86/boot/video-vesa.c b/arch/x86/boot/video-vesa.c
> > > index 7e185977a984..c2c6d35e3a43 100644
> > > --- a/arch/x86/boot/video-vesa.c
> > > +++ b/arch/x86/boot/video-vesa.c
> > > @@ -83,7 +83,7 @@ static int vesa_probe(void)
> > >    			   (vminfo.memory_layout == 4 ||
> > >    			    vminfo.memory_layout == 6) &&
> > >    			   vminfo.memory_planes == 1) {
> > > -#ifdef CONFIG_FB_BOOT_VESA_SUPPORT
> > > +#ifdef CONFIG_BOOT_VESA_SUPPORT
> > >    			/* Graphics mode, color, linear frame buffer
> > >    			   supported.  Only register the mode if
> > >    			   if framebuffer is configured, however,
> > > @@ -121,7 +121,7 @@ static int vesa_set_mode(struct mode_info *mode)
> > >    	if ((vminfo.mode_attr & 0x15) == 0x05) {
> > >    		/* It's a supported text mode */
> > >    		is_graphic = 0;
> > > -#ifdef CONFIG_FB_BOOT_VESA_SUPPORT
> > > +#ifdef CONFIG_BOOT_VESA_SUPPORT
> > >    	} else if ((vminfo.mode_attr & 0x99) == 0x99) {
> > >    		/* It's a graphics mode with linear frame buffer */
> > >    		is_graphic = 1;
> > > diff --git a/drivers/gpu/drm/tiny/Kconfig b/drivers/gpu/drm/tiny/Kconfig
> > > index 712e0004e96e..1bc30c64ed15 100644
> > > --- a/drivers/gpu/drm/tiny/Kconfig
> > > +++ b/drivers/gpu/drm/tiny/Kconfig
> > > @@ -54,6 +54,7 @@ config DRM_GM12U320
> > >    config DRM_SIMPLEDRM
> > >    	tristate "Simple framebuffer driver"
> > >    	depends on DRM && MMU
> > > +	select BOOT_VESA_SUPPORT if X86 && DRM_SIMPLEDRM = y
> >
> > We shouldn't select this option in drivers IMHO. Simple-framebuffer devices
> > with VESA are enabled with [1] and that should also select the
> > BOOT_VESA_SUPPORT.
>
> Sounds ok to select from there, it should also cover simplefb then.
>
> Thanks
>
> Michal

--
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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