Dear Linux folks,


Between Linux 5.10.103 and 5.10.110/5.15.77, matrixfb fails to load.

## Working:

     [    0.000000] Linux version 5.10.103.mx64.429 
(root@theinternet.molgen.mpg.de) (gcc (GCC) 7.5.0, GNU ld (GNU Binutils) 
2.37) #1 SMP Mon Mar 7 16:41:58 CET 2022
     [    0.000000] Command line: 
BOOT_IMAGE=/boot/bzImage-5.10.103.mx64.429 root=LABEL=root ro 
crashkernel=64G-:256M console=ttyS0,115200n8 console=tty0 
init=/bin/systemd audit=0 random.trust_cpu=on 
systemd.unified_cgroup_hierarchy
     […]
     [    0.000000] DMI: Dell Inc. PowerEdge R910/0KYD3D, BIOS 2.10.0 
08/29/2013
     […]
     [   48.045530] matroxfb: Matrox MGA-G200eW (PCI) detected
     [   48.054675] matroxfb: 640x480x8bpp (virtual: 640x13107)
     [   48.059966] matroxfb: framebuffer at 0xC5000000, mapped to 
0x00000000ca7238fa, size 8388608

## Non-working:

### 5.10.110

     [    0.000000] Linux version 5.10.110.mx64.433 
(root@theinternet.molgen.mpg.de) (gcc (GCC) 7.5.0, GNU ld (GNU Binutils) 
2.37) #1 SMP Thu Apr 14 15:28:53 CEST 2022
     [    0.000000] Command line: root=LABEL=root ro 
crashkernel=64G-:256M console=ttyS0,115200n8 console=tty0 
init=/bin/systemd audit=0 random.trust_cpu=on 
systemd.unified_cgroup_hierarchy
     […]
     [    0.000000] DMI: Dell Inc. PowerEdge R910/0KYD3D, BIOS 2.10.0 
08/29/2013
     […]
     [   35.225987] matroxfb: Matrox MGA-G200eW (PCI) detected
     [   35.234088] matroxfb: cannot determine memory size
     [   35.238931] matroxfb: probe of 0000:09:03.0 failed with error -1

### 5.15.77

     [    0.000000] Linux version 5.15.77.mx64.440 
(root@theinternet.molgen.mpg.de) (gcc (GCC) 10.4.0, GNU ld (GNU 
Binutils) 2.37) #1 SMP Tue Nov 8 15:42:33 CET 2022
     [    0.000000] Command line: root=LABEL=root ro 
crashkernel=64G-:256M console=ttyS0,115200n8 console=tty0 
init=/bin/systemd audit=0 random.trust_cpu=on 
systemd.unified_cgroup_hierarchy

     […]
     [    0.000000] DMI: Dell Inc. PowerEdge R715/0G2DP3, BIOS 1.5.2 
04/19/2011
     […]
     [    9.436420] matroxfb: Matrox MGA-G200eW (PCI) detected
     [    9.444502] matroxfb: cannot determine memory size
     [    9.449316] matroxfb: probe of 0000:0a:03.0 failed with error -1

We see it on several systems:

     $ lspci -nn -s 0a:03.0 # Dell PowerEdge R715
     0a:03.0 VGA compatible controller [0300]: Matrox Electronics 
Systems Ltd. MGA G200eW WPCM450 [102b:0532] (rev 0a)

     $ lspci -nn -s 09:03.0 # Dell PowerEdge R910
     09:03.0 VGA compatible controller [0300]: Matrox Electronics 
Systems Ltd. MGA G200eW WPCM450 [102b:0532] (rev 0a)

I found some old log from April 2022, where I booted 5.10.109, and the 
error is not there, pointing toward the regression to be introduced 
between 5.10.109 and 5.10.110.

```
$ git log --oneline v5.10.109..v5.10.110 --grep fbdev
b1c28577529c video: fbdev: sm712fb: Fix crash in smtcfb_write()
681a317034b2 video: fbdev: udlfb: replace snprintf in show functions 
with sysfs_emit
a7c624abf694 video: fbdev: omapfb: panel-tpo-td043mtea1: Use 
sysfs_emit() instead of snprintf()
543dae0a46b0 video: fbdev: omapfb: panel-dsi-cm: Use sysfs_emit() 
instead of snprintf()
da210b1b551c video: fbdev: omapfb: acx565akm: replace snprintf with 
sysfs_emit
8c7e2141fb89 video: fbdev: cirrusfb: check pixclock to avoid divide by zero
1e33f197468f video: fbdev: w100fb: Reset global state
08dff4820127 video: fbdev: nvidiafb: Use strscpy() to prevent buffer 
overflow
066d9b48f949 video: fbdev: omapfb: Add missing of_node_put() in 
dvic_probe_of
bf4bad1114a3 video: fbdev: fbcvt.c: fix printing in fb_cvt_print_name()
6de6a64f23a6 video: fbdev: atmel_lcdfb: fix an error code in 
atmel_lcdfb_probe()
64ec3e678d76 video: fbdev: smscufx: Fix null-ptr-deref in ufx_usb_probe()
0dff86aeb191 video: fbdev: controlfb: Fix COMPILE_TEST build
ec1c20b02ae0 video: fbdev: controlfb: Fix set but not used warnings
f8bf19f7f311 video: fbdev: matroxfb: set maxvram of vbG200eW to the same 
as vbG200 to avoid black screen
2ca2a5552a83 video: fbdev: atari: Atari 2 bpp (STe) palette bugfix
72af8810922e video: fbdev: sm712fb: Fix crash in smtcfb_read()
```

Is it worthwhile to test commit f8bf19f7f311 (video: fbdev: matroxfb: 
set maxvram of vbG200eW to the same as vbG200 to avoid black screen)?

The master commit 62d89a7d49a was added to v5.18-rc1, and was also 
backported to the Linux 5.15 series in 5.15.33.


Kind regards,

Paul