fbdev: sm712fb: fix brightness control on reboot, don't set SR30
On a Thinkpad s30 (Pentium III / i440MX, Lynx3DM), rebooting with sm712fb framebuffer driver would cause the role of brightness up/down button to swap. Experiments showed the FPR30 register caused this behavior. Moreover, even if this register don't have side-effect on other systems, over- writing it is also highly questionable, since it was originally configurated by the motherboard manufacturer by hardwiring pull-down resistors to indicate the type of LCD panel. We should not mess with it. Stop writing to the SR30 (a.k.a FPR30) register. Signed-off-by: Yifeng Li <tomli@tomli.me> Tested-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com> Cc: Teddy Wang <teddy.wang@siliconmotion.com> Cc: <stable@vger.kernel.org> # v4.4+ Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
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