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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: 0db5b61e0d ("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: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Tzung-Bi Shih <tzungbi@kernel.org>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://lore.kernel.org/r/20250603154838.401882-1-tzimmermann@suse.de
This commit is contained in:
Thomas Zimmermann 2025-06-03 17:48:20 +02:00
parent 2f29b5c231
commit f670b50ef5
1 changed files with 18 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

26
drivers/firmware/sysfb.c
View File

@ -143,6 +143,7 @@ static __init int sysfb_init(void)
{ {
struct screen_info *si = &screen_info; struct screen_info *si = &screen_info;
struct device *parent; struct device *parent;
unsigned int type;
struct simplefb_platform_data mode; struct simplefb_platform_data mode;
const char *name; const char *name;
bool compatible; bool compatible;
@ -170,17 +171,26 @@ static __init int sysfb_init(void)
goto put_device; goto put_device;
} }
type = screen_info_video_type(si);
/* if the FB is incompatible, create a legacy framebuffer device */ /* if the FB is incompatible, create a legacy framebuffer device */
if (si->orig_video_isVGA == VIDEO_TYPE_EFI) switch (type) {
name = "efi-framebuffer"; case VIDEO_TYPE_EGAC:
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)
name = "ega-framebuffer"; 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"; name = "platform-framebuffer";
break;
}
pd = platform_device_alloc(name, 0); pd = platform_device_alloc(name, 0);
if (!pd) { if (!pd) {