Linux >= 5.14.12 and 5.15-rc5 fail to show anything on the screen with CONFIG_DRM_SIMPLEDRM=y
Hello,
Kernel 5.14.12 introduced this change, git commit ec7cc3f74b4236860ce612656aa5be7936d1c594:
--- a/linux-5.14.11/drivers/video/fbdev/Kconfig +++ b/linux-5.14.12/drivers/video/fbdev/Kconfig @@ -2191,8 +2191,9 @@ config FB_HYPERV This framebuffer driver supports Microsoft Hyper-V Synthetic Video.
config FB_SIMPLE - bool "Simple framebuffer support" - depends on (FB = y) && !DRM_SIMPLEDRM + tristate "Simple framebuffer support" + depends on FB + depends on !DRM_SIMPLEDRM select FB_CFB_FILLRECT select FB_CFB_COPYAREA select FB_CFB_IMAGEBLIT
However if you enable CONFIG_DRM_SIMPLEDRM=y along with it, the system will show a black screen on boot while logging these messages:
[drm] Initialized simpledrm 1.0.0 20200625 for simple-framebuffer.0 on minor 0 simple-framebuffer simple-framebuffer.0: [drm] *ERROR* fbdev: Failed to setup generic emulation (ret=-22) fbcon: Taking over console
When CONFIG_DRM_SIMPLEDRM is disabled it proceeds to boot normally:
simple-framebuffer simple-framebuffer.0: framebuffer at 0xe1000000, 0x300000 bytes simple-framebuffer simple-framebuffer.0: format=a8r8g8b8, mode=1024x768x32, linelength=4096 fbcon: Deferring console take-over simple-framebuffer simple-framebuffer.0: fb0: simplefb registered!
This is discussed here: https://bugzilla.kernel.org/show_bug.cgi?id=214723
I really don't know what to make of it but I definitely don't like this situation.
Best regards, Artem
Hi
Am 22.10.21 um 14:15 schrieb Artem S. Tashkinov:
Hello,
Kernel 5.14.12 introduced this change, git commit ec7cc3f74b4236860ce612656aa5be7936d1c594:
--- a/linux-5.14.11/drivers/video/fbdev/Kconfig +++ b/linux-5.14.12/drivers/video/fbdev/Kconfig @@ -2191,8 +2191,9 @@ config FB_HYPERV This framebuffer driver supports Microsoft Hyper-V Synthetic Video.
config FB_SIMPLE - bool "Simple framebuffer support" - depends on (FB = y) && !DRM_SIMPLEDRM + tristate "Simple framebuffer support" + depends on FB + depends on !DRM_SIMPLEDRM select FB_CFB_FILLRECT select FB_CFB_COPYAREA select FB_CFB_IMAGEBLIT
However if you enable CONFIG_DRM_SIMPLEDRM=y along with it, the system will show a black screen on boot while logging these messages:
[drm] Initialized simpledrm 1.0.0 20200625 for simple-framebuffer.0 on minor 0 simple-framebuffer simple-framebuffer.0: [drm] *ERROR* fbdev: Failed to setup generic emulation (ret=-22) fbcon: Taking over console
When CONFIG_DRM_SIMPLEDRM is disabled it proceeds to boot normally:
simple-framebuffer simple-framebuffer.0: framebuffer at 0xe1000000, 0x300000 bytes simple-framebuffer simple-framebuffer.0: format=a8r8g8b8, mode=1024x768x32, linelength=4096 fbcon: Deferring console take-over simple-framebuffer simple-framebuffer.0: fb0: simplefb registered!
This is discussed here: https://bugzilla.kernel.org/show_bug.cgi?id=214723
I really don't know what to make of it but I definitely don't like this situation.
You might need commit b693e42921e0 ("drm/fbdev: Clamp fbdev surface size if too large"), which is only in -rc6.
Alternatively, make sure that fbdev overallocation has been disabled. The config that is attached to that bug report indicate that it's enabled.
CONFIG_DRM_FBDEV_OVERALLOC=300
Temporarily set this value to 100 for now.
Sorry for any problems with simpledrm. It's still new and we're fixing the bug that it exposes.
BTW, you also have to make your bootloader pass the graphics mode to Linux. (GRUB_GFXPAYLOAD_LINUX="keep" for GRUB [1]).
Best regards Thomas
[1] https://www.gnu.org/software/grub/manual/grub/html_node/gfxpayload.html
Best regards, Artem
On Fri, Oct 22, 2021 at 2:15 PM Artem S. Tashkinov aros@gmx.com wrote:
Kernel 5.14.12 introduced this change, git commit ec7cc3f74b4236860ce612656aa5be7936d1c594:
--- a/linux-5.14.11/drivers/video/fbdev/Kconfig +++ b/linux-5.14.12/drivers/video/fbdev/Kconfig @@ -2191,8 +2191,9 @@ config FB_HYPERV This framebuffer driver supports Microsoft Hyper-V Synthetic Video.
config FB_SIMPLE
- bool "Simple framebuffer support"
- depends on (FB = y) && !DRM_SIMPLEDRM
- tristate "Simple framebuffer support"
- depends on FB
- depends on !DRM_SIMPLEDRM select FB_CFB_FILLRECT select FB_CFB_COPYAREA select FB_CFB_IMAGEBLIT
However if you enable CONFIG_DRM_SIMPLEDRM=y along with it, the system will show a black screen on boot while logging these messages:
[drm] Initialized simpledrm 1.0.0 20200625 for simple-framebuffer.0 on minor 0 simple-framebuffer simple-framebuffer.0: [drm] *ERROR* fbdev: Failed to setup generic emulation (ret=-22) fbcon: Taking over console
If you want to help debug this, you can try adding a few printk statements around this code that could run into -EINVAL (22):
drm_file_alloc() ... if (dev->driver->open) { ret = dev->driver->open(dev, file); if (ret < 0) goto out_prime_destroy; }
or static int drm_fb_helper_single_fb_probe(struct drm_fb_helper *fb_helper, int preferred_bpp) ... ret = (*fb_helper->funcs->fb_probe)(fb_helper, &sizes); or static int do_fbcon_takeover(int show_logo) ... if (!num_registered_fb) return -ENODEV;
and then go from there.
When CONFIG_DRM_SIMPLEDRM is disabled it proceeds to boot normally: simple-framebuffer simple-framebuffer.0: framebuffer at 0xe1000000, 0x300000 bytes simple-framebuffer simple-framebuffer.0: format=a8r8g8b8, mode=1024x768x32, linelength=4096 fbcon: Deferring console take-over simple-framebuffer simple-framebuffer.0: fb0: simplefb registered!
Ok, good, so FB_SIMPLE continues to work as expected if it's built-in.
When the driver is a loadable module, it should work once you load the module, but that is only after the system is fully booted. It's possible that there is a bug with the module loading.
In the meantime I would suggest to keep using FB_SIMPLE=y if that works for you.
Arnd
dri-devel@lists.freedesktop.org
-
Arnd Bergmann -
Artem S. Tashkinov -
Thomas Zimmermann