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=-9.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,INCLUDES_PATCH,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 EC6A8C28CC1 for ; Sat, 1 Jun 2019 13:28:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C6DA024937 for ; Sat, 1 Jun 2019 13:28:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1559395703; bh=SdmJgg9i0oL99XPrS1akKU3rtqQfDrOm2qN4nOR7m84=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=jtbIr/PUuTJIMqPR4U1XmMtvBxEY/k4t5D0CRg5hSasC47sbkKKGWrqN9e7CM68cQ LnpcAL2jtEYXGCw+0tHnOuKYqg4pP0t175XIpqz3wzmD8bffFhpyDOBjrYzrf9Ussz 94m3v/tcizfYho4vHi1zBnRRffdGhut77XLtGhBU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730035AbfFAN2S (ORCPT ); Sat, 1 Jun 2019 09:28:18 -0400 Received: from mail.kernel.org ([198.145.29.99]:58376 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729941AbfFAN1Y (ORCPT ); Sat, 1 Jun 2019 09:27:24 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id E2640212F5; Sat, 1 Jun 2019 13:27:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1559395643; bh=SdmJgg9i0oL99XPrS1akKU3rtqQfDrOm2qN4nOR7m84=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=L0Th5bWYQvQH6AWBbdmjQ1Z3egJigRkN3umzDTQ5bYZz7jj8bB1omLREUuz2I1fXn gmOODybTaiGVEL+PTbtRgwvkgyt8kw2LXr8w343UYqAx/RnK+n3DTWLTiovz87r/KX XB98wvjBt4dCL43ro70y1mKuJfLDBDj8gxX1IADY= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Yifeng Li , Sudip Mukherjee , Teddy Wang , Bartlomiej Zolnierkiewicz , Sasha Levin , linux-fbdev@vger.kernel.org, dri-devel@lists.freedesktop.org Subject: [PATCH AUTOSEL 4.4 47/56] fbdev: sm712fb: fix white screen of death on reboot, don't set CR3B-CR3F Date: Sat, 1 Jun 2019 09:25:51 -0400 Message-Id: <20190601132600.27427-47-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190601132600.27427-1-sashal@kernel.org> References: <20190601132600.27427-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore 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 [ Upstream commit 8069053880e0ee3a75fd6d7e0a30293265fe3de4 ] 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: Sasha Levin --- drivers/video/fbdev/sm712fb.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/video/fbdev/sm712fb.c b/drivers/video/fbdev/sm712fb.c index 3f5840aaa1dd0..5148765f007cf 100644 --- a/drivers/video/fbdev/sm712fb.c +++ b/drivers/video/fbdev/sm712fb.c @@ -1182,8 +1182,12 @@ static void sm7xx_set_timing(struct smtcfb_info *sfb) 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++) -- 2.20.1