releases/4.4.181/fbdev-sm712fb-fix-brightness-control-on-reboot-don-t-set-sr30.patch

   1 From 5481115e25e42b9215f2619452aa99c95f08492f Mon Sep 17 00:00:00 2001
   2 From: Yifeng Li <tomli@tomli.me>
   3 Date: Mon, 1 Apr 2019 17:46:58 +0200
   4 Subject: fbdev: sm712fb: fix brightness control on reboot, don't set SR30
   5
   6 From: Yifeng Li <tomli@tomli.me>
   7
   8 commit 5481115e25e42b9215f2619452aa99c95f08492f upstream.
   9
  10 On a Thinkpad s30 (Pentium III / i440MX, Lynx3DM), rebooting with
  11 sm712fb framebuffer driver would cause the role of brightness up/down
  12 button to swap.
  13
  14 Experiments showed the FPR30 register caused this behavior. Moreover,
  15 even if this register don't have side-effect on other systems, over-
  16 writing it is also highly questionable, since it was originally
  17 configurated by the motherboard manufacturer by hardwiring pull-down
  18 resistors to indicate the type of LCD panel. We should not mess with
  19 it.
  20
  21 Stop writing to the SR30 (a.k.a FPR30) register.
  22
  23 Signed-off-by: Yifeng Li <tomli@tomli.me>
  24 Tested-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
  25 Cc: Teddy Wang <teddy.wang@siliconmotion.com>
  26 Cc: <stable@vger.kernel.org>  # v4.4+
  27 Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
  28 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  29
  30 ---
  31  drivers/video/fbdev/sm712fb.c |    4 ++--
  32  1 file changed, 2 insertions(+), 2 deletions(-)
  33
  34 --- a/drivers/video/fbdev/sm712fb.c
  35 +++ b/drivers/video/fbdev/sm712fb.c
  36 @@ -1144,8 +1144,8 @@ static void sm7xx_set_timing(struct smtc
  37
  38                 /* init SEQ register SR30 - SR75 */
  39                 for (i = 0; i < SIZE_SR30_SR75; i++)
  40 -                       if ((i + 0x30) != 0x62 && (i + 0x30) != 0x6a &&
  41 -                           (i + 0x30) != 0x6b)
  42 +                       if ((i + 0x30) != 0x30 && (i + 0x30) != 0x62 &&
  43 +                           (i + 0x30) != 0x6a && (i + 0x30) != 0x6b)
  44                                 smtc_seqw(i + 0x30,
  45                                           vgamode[j].init_sr30_sr75[i]);
  46