Re: [PATCH 2/8] fbdev: sm712fb: fix brightness control on reboot, don't set SR30.

Sudip Mukherjee
2019-03-31T12:19:07Z

On Sun, Mar 17, 2019 at 06:24:58AM +0800, Yifeng Li wrote:
> 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>
> Cc: stable@vger.kernel.org # v4.4+

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

--
Regards
Sudip