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=-7.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,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 8AB27C2F3BE for ; Mon, 21 Jan 2019 13:57:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 593B12087F for ; Mon, 21 Jan 2019 13:57:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1548079061; bh=IfUMN1k+x/RkAR4LPmO9D7YEA8+Fi81eQXKjRqmRvHk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=OpoMk8T8aIIPN/ejbrIhSJqyDrqCEGNOzNFGAIYvB4YXQ6rCVXqm/NHCtvZCDPsNP W8K3+WZh/TL9LBkmvaWtzSTEPQtSfHlz97pw3957QhhTVw6bynIyiEGPevJooTmWGs C5SiHQ0wgfukSylOYfd0+SzVAcHLdq1uuTnAPXpg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731503AbfAUN5j (ORCPT ); Mon, 21 Jan 2019 08:57:39 -0500 Received: from mail.kernel.org ([198.145.29.99]:41374 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731894AbfAUN4R (ORCPT ); Mon, 21 Jan 2019 08:56:17 -0500 Received: from localhost (5356596B.cm-6-7b.dynamic.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 5424720861; Mon, 21 Jan 2019 13:56:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1548078976; bh=IfUMN1k+x/RkAR4LPmO9D7YEA8+Fi81eQXKjRqmRvHk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=qNkVLbnLYQtDRg46LaYd4QieWuLFV4PwmCXsQz4yT4zFYTp9I+AqKnl1rLxskjD2l 00VwvxtJqeuotRnIyHnjgY0uTcDLqAXH6ECccRzMrXb9jOB8/LDlK4EBpz1m2cE7xf aFy7Z5QDyQEmBYblgt0Uad+BtlVKxLUWCGAeB9sI= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Ivan Mironov , Daniel Vetter Subject: [PATCH 4.9 50/51] drm/fb-helper: Ignore the value of fb_var_screeninfo.pixclock Date: Mon, 21 Jan 2019 14:44:46 +0100 Message-Id: <20190121122458.709741268@linuxfoundation.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190121122453.700446926@linuxfoundation.org> References: <20190121122453.700446926@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore 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 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ivan Mironov commit 66a8d5bfb518f9f12d47e1d2dce1732279f9451e upstream. Strict requirement of pixclock to be zero breaks support of SDL 1.2 which contains hardcoded table of supported video modes with non-zero pixclock values[1]. To better understand which pixclock values are considered valid and how driver should handle these values, I briefly examined few existing fbdev drivers and documentation in Documentation/fb/. And it looks like there are no strict rules on that and actual behaviour varies: * some drivers treat (pixclock == 0) as "use defaults" (uvesafb.c); * some treat (pixclock == 0) as invalid value which leads to -EINVAL (clps711x-fb.c); * some pass converted pixclock value to hardware (uvesafb.c); * some are trying to find nearest value from predefined table (vga16fb.c, video_gx.c). Given this, I believe that it should be safe to just ignore this value if changing is not supported. It seems that any portable fbdev application which was not written only for one specific device working under one specific kernel version should not rely on any particular behaviour of pixclock anyway. However, while enabling SDL1 applications to work out of the box when there is no /etc/fb.modes with valid settings, this change affects the video mode choosing logic in SDL. Depending on current screen resolution, contents of /etc/fb.modes and resolution requested by application, this may lead to user-visible difference (not always): image will be displayed in a right way, but it will be aligned to the left instead of center. There is no "right behaviour" here as well, as emulated fbdev, opposing to old fbdev drivers, simply ignores any requsts of video mode changes with resolutions smaller than current. The easiest way to reproduce this problem is to install sdl-sopwith[2], remove /etc/fb.modes file if it exists, and then try to run sopwith from console without X. At least in Fedora 29, sopwith may be simply installed from standard repositories. [1] SDL 1.2.15 source code, src/video/fbcon/SDL_fbvideo.c, vesa_timings [2] http://sdl-sopwith.sourceforge.net/ Signed-off-by: Ivan Mironov Cc: stable@vger.kernel.org Fixes: 79e539453b34e ("DRM: i915: add mode setting support") Fixes: 771fe6b912fca ("drm/radeon: introduce kernel modesetting for radeon hardware") Fixes: 785b93ef8c309 ("drm/kms: move driver specific fb common code to helper functions (v2)") Signed-off-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/20190108072353.28078-3-mironov.ivan@gmail.com Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/drm_fb_helper.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) --- a/drivers/gpu/drm/drm_fb_helper.c +++ b/drivers/gpu/drm/drm_fb_helper.c @@ -1238,9 +1238,14 @@ int drm_fb_helper_check_var(struct fb_va struct drm_framebuffer *fb = fb_helper->fb; int depth; - if (var->pixclock != 0 || in_dbg_master()) + if (in_dbg_master()) return -EINVAL; + if (var->pixclock != 0) { + DRM_DEBUG("fbdev emulation doesn't support changing the pixel clock, value of pixclock is ignored\n"); + var->pixclock = 0; + } + /* Need to resize the fb object !!! */ if (var->bits_per_pixel > fb->bits_per_pixel || var->xres > fb->width || var->yres > fb->height ||