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=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED 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 2D026C43218 for ; Sat, 27 Apr 2019 15:26:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EF933208C2 for ; Sat, 27 Apr 2019 15:26:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728493AbfD0P01 (ORCPT ); Sat, 27 Apr 2019 11:26:27 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:34896 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728482AbfD0P0Y (ORCPT ); Sat, 27 Apr 2019 11:26:24 -0400 Received: from [192.168.4.242] (helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1hKP3E-0000zO-3a; Sat, 27 Apr 2019 16:15:40 +0100 Received: from ben by deadeye with local (Exim 4.92) (envelope-from ) id 1hKP2h-0004PU-LV; Sat, 27 Apr 2019 16:15:07 +0100 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, Denis Kirjanov , "saahriktu" , "Ivan Mironov" , "Daniel Vetter" Date: Sat, 27 Apr 2019 16:13:09 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) X-Patchwork-Hint: ignore Subject: [PATCH 3.16 024/202] drm/fb-helper: Partially bring back workaround for bugs of SDL 1.2 In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.242 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.66-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Ivan Mironov commit 62d85b3bf9d978ed4b6b2aeef5cf0ccf1423906e upstream. SDL 1.2 sets all fields related to the pixel format to zero in some cases[1]. Prior to commit db05c48197759 ("drm: fb-helper: Reject all pixel format changing requests"), there was an unintentional workaround for this that existed for more than a decade. First in device-specific DRM drivers, then here in drm_fb_helper.c. Previous code containing this workaround just ignores pixel format fields from userspace code. Not a good thing either, as this way, driver may silently use pixel format different from what client actually requested, and this in turn will lead to displaying garbage on the screen. I think that returning EINVAL to userspace in this particular case is the right option, so I decided to left code from problematic commit untouched instead of just reverting it entirely. Here is the steps required to reproduce this problem exactly: 1) Compile fceux[2] with SDL 1.2.15 and without GTK or OpenGL support. SDL should be compiled with fbdev support (which is on by default). 2) Create /etc/fb.modes with following contents (values seems not used, and just required to trigger problematic code in SDL): mode "test" geometry 1 1 1 1 1 timings 1 1 1 1 1 1 1 endmode 3) Create ~/.fceux/fceux.cfg with following contents: SDL.Hotkeys.Quit = 27 SDL.DoubleBuffering = 1 4) Ensure that screen resolution is at least 1280x960 (e.g. append "video=Virtual-1:1280x960-32" to the kernel cmdline for qemu/QXL). 5) Try to run fceux on VT with some ROM file[3]: # ./fceux color_test.nes [1] SDL 1.2.15 source code, src/video/fbcon/SDL_fbvideo.c, FB_SetVideoMode() [2] http://www.fceux.com [3] Example ROM: https://github.com/bokuweb/rustynes/blob/master/roms/color_test.nes Reported-by: saahriktu Suggested-by: saahriktu Fixes: db05c48197759 ("drm: fb-helper: Reject all pixel format changing requests") Signed-off-by: Ivan Mironov [danvet: Delete misleading comment.] Signed-off-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/20190108072353.28078-2-mironov.ivan@gmail.com Link: https://patchwork.freedesktop.org/patch/msgid/20190108072353.28078-2-mironov.ivan@gmail.com [bwh: Backported to 3.16: - Use fb->depth instead of fb->format->depth - Adjust context] Signed-off-by: Ben Hutchings --- drivers/gpu/drm/drm_fb_helper.c | 126 ++++++++++++++++++-------------- 1 file changed, 73 insertions(+), 53 deletions(-) --- a/drivers/gpu/drm/drm_fb_helper.c +++ b/drivers/gpu/drm/drm_fb_helper.c @@ -769,6 +769,64 @@ static bool drm_fb_pixel_format_equal(co var_1->transp.msb_right == var_2->transp.msb_right; } +static void drm_fb_helper_fill_pixel_fmt(struct fb_var_screeninfo *var, + u8 depth) +{ + switch (depth) { + case 8: + var->red.offset = 0; + var->green.offset = 0; + var->blue.offset = 0; + var->red.length = 8; /* 8bit DAC */ + var->green.length = 8; + var->blue.length = 8; + var->transp.offset = 0; + var->transp.length = 0; + break; + case 15: + var->red.offset = 10; + var->green.offset = 5; + var->blue.offset = 0; + var->red.length = 5; + var->green.length = 5; + var->blue.length = 5; + var->transp.offset = 15; + var->transp.length = 1; + break; + case 16: + var->red.offset = 11; + var->green.offset = 5; + var->blue.offset = 0; + var->red.length = 5; + var->green.length = 6; + var->blue.length = 5; + var->transp.offset = 0; + break; + case 24: + var->red.offset = 16; + var->green.offset = 8; + var->blue.offset = 0; + var->red.length = 8; + var->green.length = 8; + var->blue.length = 8; + var->transp.offset = 0; + var->transp.length = 0; + break; + case 32: + var->red.offset = 16; + var->green.offset = 8; + var->blue.offset = 0; + var->red.length = 8; + var->green.length = 8; + var->blue.length = 8; + var->transp.offset = 24; + var->transp.length = 8; + break; + default: + break; + } +} + /** * drm_fb_helper_check_var - implementation for ->fb_check_var * @var: screeninfo to check @@ -796,6 +854,20 @@ int drm_fb_helper_check_var(struct fb_va } /* + * Workaround for SDL 1.2, which is known to be setting all pixel format + * fields values to zero in some cases. We treat this situation as a + * kind of "use some reasonable autodetected values". + */ + if (!var->red.offset && !var->green.offset && + !var->blue.offset && !var->transp.offset && + !var->red.length && !var->green.length && + !var->blue.length && !var->transp.length && + !var->red.msb_right && !var->green.msb_right && + !var->blue.msb_right && !var->transp.msb_right) { + drm_fb_helper_fill_pixel_fmt(var, fb->depth); + } + + /* * drm fbdev emulation doesn't support changing the pixel format at all, * so reject all pixel format changing requests. */ @@ -1058,59 +1130,7 @@ void drm_fb_helper_fill_var(struct fb_in info->var.height = -1; info->var.width = -1; - switch (fb->depth) { - case 8: - info->var.red.offset = 0; - info->var.green.offset = 0; - info->var.blue.offset = 0; - info->var.red.length = 8; /* 8bit DAC */ - info->var.green.length = 8; - info->var.blue.length = 8; - info->var.transp.offset = 0; - info->var.transp.length = 0; - break; - case 15: - info->var.red.offset = 10; - info->var.green.offset = 5; - info->var.blue.offset = 0; - info->var.red.length = 5; - info->var.green.length = 5; - info->var.blue.length = 5; - info->var.transp.offset = 15; - info->var.transp.length = 1; - break; - case 16: - info->var.red.offset = 11; - info->var.green.offset = 5; - info->var.blue.offset = 0; - info->var.red.length = 5; - info->var.green.length = 6; - info->var.blue.length = 5; - info->var.transp.offset = 0; - break; - case 24: - info->var.red.offset = 16; - info->var.green.offset = 8; - info->var.blue.offset = 0; - info->var.red.length = 8; - info->var.green.length = 8; - info->var.blue.length = 8; - info->var.transp.offset = 0; - info->var.transp.length = 0; - break; - case 32: - info->var.red.offset = 16; - info->var.green.offset = 8; - info->var.blue.offset = 0; - info->var.red.length = 8; - info->var.green.length = 8; - info->var.blue.length = 8; - info->var.transp.offset = 24; - info->var.transp.length = 8; - break; - default: - break; - } + drm_fb_helper_fill_pixel_fmt(&info->var, fb->depth); info->var.xres = fb_width; info->var.yres = fb_height;