| From 5481115e25e42b9215f2619452aa99c95f08492f Mon Sep 17 00:00:00 2001 |
| From: Yifeng Li <tomli@tomli.me> |
| Date: Mon, 1 Apr 2019 17:46:58 +0200 |
| Subject: fbdev: sm712fb: fix brightness control on reboot, don't set SR30 |
| |
| From: Yifeng Li <tomli@tomli.me> |
| |
| commit 5481115e25e42b9215f2619452aa99c95f08492f upstream. |
| |
| 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> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| drivers/video/fbdev/sm712fb.c | 4 ++-- |
| 1 file changed, 2 insertions(+), 2 deletions(-) |
| |
| --- a/drivers/video/fbdev/sm712fb.c |
| +++ b/drivers/video/fbdev/sm712fb.c |
| @@ -1144,8 +1144,8 @@ static void sm7xx_set_timing(struct smtc |
| |
| /* init SEQ register SR30 - SR75 */ |
| for (i = 0; i < SIZE_SR30_SR75; i++) |
| - if ((i + 0x30) != 0x62 && (i + 0x30) != 0x6a && |
| - (i + 0x30) != 0x6b) |
| + if ((i + 0x30) != 0x30 && (i + 0x30) != 0x62 && |
| + (i + 0x30) != 0x6a && (i + 0x30) != 0x6b) |
| smtc_seqw(i + 0x30, |
| vgamode[j].init_sr30_sr75[i]); |
| |
