From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sudip Mukherjee Date: Sun, 31 Mar 2019 12:19:07 +0000 Subject: Re: [PATCH 2/8] fbdev: sm712fb: fix brightness control on reboot, don't set SR30. Message-Id: <20190331121907.npu4kehmgxmmf44j@debian> List-Id: References: <20190316222504.27170-1-tomli@tomli.me> <20190316222504.27170-3-tomli@tomli.me> In-Reply-To: <20190316222504.27170-3-tomli@tomli.me> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Yifeng Li Cc: Teddy Wang , Bartlomiej Zolnierkiewicz , linux-fbdev@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org 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 > Cc: stable@vger.kernel.org # v4.4+ Tested-by: Sudip Mukherjee -- Regards Sudip