From mboxrd@z Thu Jan 1 00:00:00 1970 From: Yifeng Li Date: Sat, 16 Mar 2019 22:24:58 +0000 Subject: [PATCH 2/8] fbdev: sm712fb: fix brightness control on reboot, don't set SR30. Message-Id: <20190316222504.27170-3-tomli@tomli.me> List-Id: References: <20190316222504.27170-1-tomli@tomli.me> In-Reply-To: <20190316222504.27170-1-tomli@tomli.me> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Sudip Mukherjee , Teddy Wang Cc: Bartlomiej Zolnierkiewicz , linux-fbdev@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, Yifeng Li , stable@vger.kernel.org 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 Cc: stable@vger.kernel.org # v4.4+ --- drivers/video/fbdev/sm712fb.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/video/fbdev/sm712fb.c b/drivers/video/fbdev/sm712fb.c index d05379affa32..a19655babf67 100644 --- a/drivers/video/fbdev/sm712fb.c +++ b/drivers/video/fbdev/sm712fb.c @@ -1145,8 +1145,8 @@ static void sm7xx_set_timing(struct smtcfb_info *sfb) /* 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]); -- 2.20.1