From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.0 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,T_DKIMWL_WL_HIGH,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0A96DC282DD for ; Thu, 23 May 2019 19:13:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D61B0217D9 for ; Thu, 23 May 2019 19:12:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1558638779; bh=oheSv95oFkn+VVV3lf9Ovz2363O9f+rCEsKN1nvHhuA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=1CP/aY6DvoHhPlvJjn3jsOLigHlnBIVta6UghxQ0QcfUH5Kt+GA8Ah6PUZTwOoAOg tnO5TIPiKK7iqPin5D7MBKLVcZ+/poaDQjrRI4toKgyL1soc3LSzJ/nKf5WX5KW4vV sbwGanU7rDZlDcCOKwQuvbwSq9A7jXcWJd1ef96g= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387873AbfEWTM7 (ORCPT ); Thu, 23 May 2019 15:12:59 -0400 Received: from mail.kernel.org ([198.145.29.99]:46720 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731947AbfEWTMz (ORCPT ); Thu, 23 May 2019 15:12:55 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 70B3E20863; Thu, 23 May 2019 19:12:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1558638774; bh=oheSv95oFkn+VVV3lf9Ovz2363O9f+rCEsKN1nvHhuA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=dfrVJo9BgDxCH/1+ByE0tt9MH17fIxjLLNwIFSN3gGNLRjsFd3VNauuy7Gx7y5lsE SLhVOKJbtpifXvuqDkXEyEhGphFSb1KntSgD66XL5/t1RgCkW+FeEGa9vBcyRz1gg9 qOQM4ylR+ehQ0myQ/zUzOoUiMssG1Gd+UEqiXO5c= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Yifeng Li , Sudip Mukherjee , Teddy Wang , Bartlomiej Zolnierkiewicz Subject: [PATCH 4.14 43/77] fbdev: sm712fb: fix white screen of death on reboot, dont set CR3B-CR3F Date: Thu, 23 May 2019 21:06:01 +0200 Message-Id: <20190523181726.086206319@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190523181719.982121681@linuxfoundation.org> References: <20190523181719.982121681@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Yifeng Li commit 8069053880e0ee3a75fd6d7e0a30293265fe3de4 upstream. On a Thinkpad s30 (Pentium III / i440MX, Lynx3DM), rebooting with sm712fb framebuffer driver would cause a white screen of death on the next POST, presumably the proper timings for the LCD panel was not reprogrammed properly by the BIOS. Experiments showed a few CRTC Scratch Registers, including CRT3D, CRT3E and CRT3F may be used internally by BIOS as some flags. CRT3B is a hardware testing register, we shouldn't mess with it. CRT3C has blanking signal and line compare control, which is not needed for this driver. Stop writing to CR3B-CR3F (a.k.a CRT3B-CRT3F) registers. Even if these registers don't have side-effect on other systems, writing to them is also highly questionable. Signed-off-by: Yifeng Li Tested-by: Sudip Mukherjee Cc: Teddy Wang Cc: # v4.4+ Signed-off-by: Bartlomiej Zolnierkiewicz Signed-off-by: Greg Kroah-Hartman --- drivers/video/fbdev/sm712fb.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) --- a/drivers/video/fbdev/sm712fb.c +++ b/drivers/video/fbdev/sm712fb.c @@ -1173,8 +1173,12 @@ static void sm7xx_set_timing(struct smtc smtc_crtcw(i, vgamode[j].init_cr00_cr18[i]); /* init CRTC register CR30 - CR4D */ - for (i = 0; i < SIZE_CR30_CR4D; i++) + for (i = 0; i < SIZE_CR30_CR4D; i++) { + if ((i + 0x30) >= 0x3B && (i + 0x30) <= 0x3F) + /* side-effect, don't write to CR3B-CR3F */ + continue; smtc_crtcw(i + 0x30, vgamode[j].init_cr30_cr4d[i]); + } /* init CRTC register CR90 - CRA7 */ for (i = 0; i < SIZE_CR90_CRA7; i++)