Commit f670b50e authored by Thomas Zimmermann's avatar Thomas Zimmermann
Browse files

sysfb: Fix screen_info type check for VGA 



Use the helper screen_info_video_type() to get the framebuffer
type from struct screen_info. Handle supported values in sorted
switch statement.

Reading orig_video_isVGA is unreliable. On most systems it is a
VIDEO_TYPE_ constant. On some systems with VGA it is simply set
to 1 to signal the presence of a VGA output. See vga_probe() for
an example. Retrieving the screen_info type with the helper
screen_info_video_type() detects these cases and returns the
appropriate VIDEO_TYPE_ constant. For VGA, sysfb creates a device
named "vga-framebuffer".

The sysfb code has been taken from vga16fb, where it likely didn't
work correctly either. With this bugfix applied, vga16fb loads for
compatible vga-framebuffer devices.

Fixes: 0db5b61e ("fbdev/vga16fb: Create EGA/VGA devices in sysfb code")
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Javier Martinez Canillas <javierm@redhat.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Tzung-Bi Shih <tzungbi@kernel.org>
Cc: Helge Deller <deller@gmx.de>
Cc: "Uwe Kleine-König" <u.kleine-koenig@baylibre.com>
Cc: Zsolt Kajtar <soci@c64.rulez.org>
Cc: <stable@vger.kernel.org> # v6.1+
Signed-off-by: default avatarThomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: default avatarTzung-Bi Shih <tzungbi@kernel.org>
Reviewed-by: default avatarJavier Martinez Canillas <javierm@redhat.com>
Link: https://lore.kernel.org/r/20250603154838.401882-1-tzimmermann@suse.de
parent 2f29b5c2

drivers/firmware/sysfb.c

+18 −8
Original line number Diff line number Diff line
@@ -143,6 +143,7 @@ static __init int sysfb_init(void) 
{

	struct screen_info *si = &screen_info;

	struct device *parent;

	unsigned int type;

	struct simplefb_platform_data mode;

	const char *name;

	bool compatible;
@@ -170,17 +171,26 @@ static __init int sysfb_init(void) 
			goto put_device;

	}



	type = screen_info_video_type(si);



	/* if the FB is incompatible, create a legacy framebuffer device */

	if (si->orig_video_isVGA == VIDEO_TYPE_EFI)

		name = "efi-framebuffer";

	else if (si->orig_video_isVGA == VIDEO_TYPE_VLFB)

		name = "vesa-framebuffer";

	else if (si->orig_video_isVGA == VIDEO_TYPE_VGAC)

		name = "vga-framebuffer";

	else if (si->orig_video_isVGA == VIDEO_TYPE_EGAC)

	switch (type) {

	case VIDEO_TYPE_EGAC:

		name = "ega-framebuffer";

	else

		break;

	case VIDEO_TYPE_VGAC:

		name = "vga-framebuffer";

		break;

	case VIDEO_TYPE_VLFB:

		name = "vesa-framebuffer";

		break;

	case VIDEO_TYPE_EFI:

		name = "efi-framebuffer";

		break;

	default:

		name = "platform-framebuffer";

		break;

	}



	pd = platform_device_alloc(name, 0);

	if (!pd) {