[PATCH 3/8] fbdev: sm712fb: fix VRAM detection, don't set SR70/71/74/75.

[Sudip Mukherjee]

On Sun, Mar 17, 2019 at 06:24:59AM +0800, Yifeng Li wrote:
> On a Thinkpad s30 (Pentium III / i440MX, Lynx3DM), the amount of Video
> RAM is not detected correctly by the xf86-video-siliconmotion driver.
> This is because sm712fb overwrites the GPR71 Scratch Pad Register, which
> is set by BIOS on x86 and used to indicate amount of VRAM.
> 
> Other Scratch Pad Registers, including GPR70/74/75, don't have the same
> side-effect, but overwriting to them is still questionable, as they are
> not related to modesetting.
> 
> Stop writing to SR70/71/74/75 (a.k.a GPR70/71/74/75).
> 
> Signed-off-by: Yifeng Li <tomli at tomli.me>
> Cc: stable at vger.kernel.org  # v4.4+

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

--
Regards
Sudip