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

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Date:   Fri, 18 Feb 2022 10:57:33 +0100
From:   Thomas Zimmermann <tzimmermann@...e.de>
To:     Michal Suchanek <msuchanek@...e.de>,
        dri-devel@...ts.freedesktop.org, linux-fbdev@...r.kernel.org
Cc:     David Airlie <airlied@...ux.ie>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>, Sam Ravnborg <sam@...nborg.org>,
        Helge Deller <deller@....de>, x86@...nel.org,
        Javier Martinez Canillas <javierm@...hat.com>,
        Ingo Molnar <mingo@...hat.com>, Arnd Bergmann <arnd@...db.de>,
        Borislav Petkov <bp@...en8.de>,
        Maxime Ripard <maxime@...no.tech>,
        Thomas Gleixner <tglx@...utronix.de>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org, Martin Mares <mj@....cz>,
        linux-video@...ey.karlin.mff.cuni.cz,
        Daniel Mack <daniel@...que.org>
Subject: Re: [PATCH] simpldrm: Enable boot time VESA graphic mode selection.

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 
concrete example of a mode that doesn't work any longer?

> 
> Fixes: 11e8f5fd223b ("drm: Add simpledrm driver")
> Signed-off-by: Michal Suchanek <msuchanek@...e.de>
> ---
>   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.

Best regards
Thomas

[1] 
https://elixir.bootlin.com/linux/v5.16.10/source/drivers/firmware/Kconfig#L224

>   	select DRM_GEM_SHMEM_HELPER
>   	select DRM_KMS_HELPER
>   	help
> diff --git a/drivers/video/fbdev/Kconfig b/drivers/video/fbdev/Kconfig
> index 6ed5e608dd04..4f3be9b7a520 100644
> --- a/drivers/video/fbdev/Kconfig
> +++ b/drivers/video/fbdev/Kconfig
> @@ -66,9 +66,8 @@ config FB_DDC
>   	select I2C_ALGOBIT
>   	select I2C
>   
> -config FB_BOOT_VESA_SUPPORT
> +config BOOT_VESA_SUPPORT
>   	bool
> -	depends on FB
>   	help
>   	  If true, at least one selected framebuffer driver can take advantage
>   	  of VESA video modes set at an early boot stage via the vga= parameter.
> @@ -627,7 +626,7 @@ config FB_VESA
>   	select FB_CFB_FILLRECT
>   	select FB_CFB_COPYAREA
>   	select FB_CFB_IMAGEBLIT
> -	select FB_BOOT_VESA_SUPPORT
> +	select BOOT_VESA_SUPPORT
>   	help
>   	  This is the frame buffer device driver for generic VESA 2.0
>   	  compliant graphic cards. The older VESA 1.2 cards are not supported.
> @@ -1051,7 +1050,7 @@ config FB_INTEL
>   	select FB_CFB_FILLRECT
>   	select FB_CFB_COPYAREA
>   	select FB_CFB_IMAGEBLIT
> -	select FB_BOOT_VESA_SUPPORT if FB_INTEL = y
> +	select BOOT_VESA_SUPPORT if FB_INTEL = y
>   	depends on !DRM_I915
>   	help
>   	  This driver supports the on-board graphics built in to the Intel
> @@ -1378,7 +1377,7 @@ config FB_SIS
>   	select FB_CFB_FILLRECT
>   	select FB_CFB_COPYAREA
>   	select FB_CFB_IMAGEBLIT
> -	select FB_BOOT_VESA_SUPPORT if FB_SIS = y
> +	select BOOT_VESA_SUPPORT if FB_SIS = y
>   	select FB_SIS_300 if !FB_SIS_315
>   	help
>   	  This is the frame buffer device driver for the SiS 300, 315, 330

-- 
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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