On Sun, Mar 17, 2019 at 06:24:57AM +0800, Yifeng Li wrote:

On a Thinkpad s30 (Pentium III / i440MX, Lynx3DM), rebooting with
sm712fb framebuffer driver would cause a white screen of death on
the next POST, presumably the proper timings for the LCD panel was
not reprogrammed properly by the BIOS.

Experiments showed a few CRTC Scratch Registers, including CRT3D,
CRT3E and CRT3F may be used internally by BIOS as some flags. CRT3B is
a hardware testing register, we shouldn't mess with it. CRT3C has
blanking signal and line compare control, which is not needed for this
driver.

Stop writing to CR3B-CR3F (a.k.a CRT3B-CRT3F) registers. Even if these
registers don't have side-effect on other systems, writing to them is
also highly questionable.

Signed-off-by: Yifeng Li <redacted>
Cc: stable@vger.kernel.org  # v4.4+

Tested-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>

--
Regards
Sudip