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=-13.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT autolearn=unavailable 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 92662C43612 for ; Tue, 8 Jan 2019 08:17:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 554B320665 for ; Tue, 8 Jan 2019 08:17:56 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=ffwll.ch header.i=@ffwll.ch header.b="Su8wtMPI" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727992AbfAHIRz (ORCPT ); Tue, 8 Jan 2019 03:17:55 -0500 Received: from mail-ed1-f67.google.com ([209.85.208.67]:34605 "EHLO mail-ed1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727689AbfAHIRz (ORCPT ); Tue, 8 Jan 2019 03:17:55 -0500 Received: by mail-ed1-f67.google.com with SMTP id b3so3323602ede.1 for ; Tue, 08 Jan 2019 00:17:53 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ffwll.ch; s=google; h=sender:date:from:to:cc:subject:message-id:mail-followup-to :references:mime-version:content-disposition:in-reply-to:user-agent; bh=zrTW/cgwRnEbkyp/pqxFAbGGTh1Sm6QSGMBFEXr65Cg=; b=Su8wtMPIWvxgtxOo9gxmM3ofvr8iuzaPUyfoOWqAPPUIw5WWy/joL0BffjT7rFPBQ4 HYL+e+UqWfOditGIMTzbHWgl+XK2wAzlJpRXRkN6hrRtDD2ENnCozaHNj8qxzWRWbUTT O+KdcP+T6bq2cqh3CwVFSd4jiCTXBvXbLNt8c= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :mail-followup-to:references:mime-version:content-disposition :in-reply-to:user-agent; bh=zrTW/cgwRnEbkyp/pqxFAbGGTh1Sm6QSGMBFEXr65Cg=; b=A9X2RgFHv+D2D9jaWnw7l2fPn5ckW+yE8/08PQykGhdJTkFVN/kRoJa/vn7DMpSWrP I4XJp0we/bC/WA7Mx0QdddCisOwqLkwy0HyEbAu032MTKxhYPQGmYcse0uwAPYY0Jx5V dEfzaY53b6ltSEoqNiJjhzSlJvfPLPs99Lri2BuFLrcrwSWWwrUY+zgiPoZv99cOYDH0 yH4AJykuZJjMQfVlAviGtcOUwUD6C6PJUs4uPvwrPqOK+iUq5mq1sXFPXbNUEVXNK3Yl wcfKEdXgJ584qsFqqagHwsGHUdlKcaIxQQ6Q+RCoOP4ovMlFIo0hWHxotMTPzZkDVfEJ Em3A== X-Gm-Message-State: AJcUuketPoeThSJvxUB3oGmp86LF6Ix7cRHQyBZ3qpf4T0Mbi3Cy2HSe pMf6TARKza5Yxp2jcgABId3fiQfzAwQ= X-Google-Smtp-Source: ALg8bN4YniGTXIjqKl2v3UTUfRYxJFEsiu/kNR7YXrDFjEPHwJFmWBCLwpGseN+iDvYZ8imCHmLBrg== X-Received: by 2002:a50:aa9b:: with SMTP id q27mr1119828edc.93.1546935472536; Tue, 08 Jan 2019 00:17:52 -0800 (PST) Received: from phenom.ffwll.local ([2a02:168:569e:0:3106:d637:d723:e855]) by smtp.gmail.com with ESMTPSA id n11sm32655002edn.14.2019.01.08.00.17.51 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 08 Jan 2019 00:17:51 -0800 (PST) Date: Tue, 8 Jan 2019 09:17:49 +0100 From: Daniel Vetter To: Ivan Mironov Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, Maarten Lankhorst , Maxime Ripard , Sean Paul , David Airlie , Daniel Vetter , saahriktu , Eugeniy Paltsev , stable@vger.kernel.org Subject: Re: [PATCH v2 1/2] drm/fb-helper: Partially bring back workaround for bugs of SDL 1.2 Message-ID: <20190108081749.GP21184@phenom.ffwll.local> Mail-Followup-To: Ivan Mironov , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, Maarten Lankhorst , Maxime Ripard , Sean Paul , David Airlie , saahriktu , Eugeniy Paltsev , stable@vger.kernel.org References: <20190108072353.28078-1-mironov.ivan@gmail.com> <20190108072353.28078-2-mironov.ivan@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190108072353.28078-2-mironov.ivan@gmail.com> X-Operating-System: Linux phenom 4.18.0-2-amd64 User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jan 08, 2019 at 12:23:52PM +0500, Ivan Mironov wrote: > 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 > Cc: stable@vger.kernel.org > Fixes: db05c48197759 ("drm: fb-helper: Reject all pixel format changing requests") > Signed-off-by: Ivan Mironov > --- > drivers/gpu/drm/drm_fb_helper.c | 142 ++++++++++++++++++++------------ > 1 file changed, 89 insertions(+), 53 deletions(-) > > diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c > index d3af098b0922..ed7e91423258 100644 > --- a/drivers/gpu/drm/drm_fb_helper.c > +++ b/drivers/gpu/drm/drm_fb_helper.c > @@ -1621,6 +1621,64 @@ static bool drm_fb_pixel_format_equal(const struct fb_var_screeninfo *var_1, > 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_ops.fb_check_var > * @var: screeninfo to check > @@ -1654,6 +1712,36 @@ int drm_fb_helper_check_var(struct fb_var_screeninfo *var, > return -EINVAL; > } > > + /* > + * 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) { > + /* > + * There is no way to guess the right value for depth when > + * bits_per_pixel is 16 or 32. Instead of restoring the > + * behaviour previously introduced here by commit 785b93ef8c309, > + * we decided to just use the current depth and do not perform > + * any guessing. > + * > + * Also, if requested bits_per_pixel differs from current, > + * the next call to drm_fb_pixel_format_equal() will fail > + * resulting in EINVAL error from ioctl(). > + * > + * However, this still leaves the theoretical possibility of > + * situation when userspace app requests different pixel format > + * and ioctl() call silently succeeds. Garbage will be displayed > + * in this case. > + */ I deleted this comment since I think it's misleading: We only need depth to decided for the pixel format when userspace hasn't filled it out. We could also change the function to instead pass fb->format, and use that as the key to fill out the fbdev format information. That's why I requested you keep Ville's change here, it was a bugfix. So ther's no guessing going on here at all, and nothing else fancy: All we do is fill out the fbdev pixel format information if userspace failed to supply it. That's imo clear enough without a comment. Applied both comments for 5.0 drm-misc-fixes, thanks a lot for your patches and debug work. Cheers, Daniel > + drm_fb_helper_fill_pixel_fmt(var, fb->format->depth); > + } > + > /* > * drm fbdev emulation doesn't support changing the pixel format at all, > * so reject all pixel format changing requests. > @@ -1967,59 +2055,7 @@ void drm_fb_helper_fill_var(struct fb_info *info, struct drm_fb_helper *fb_helpe > info->var.yoffset = 0; > info->var.activate = FB_ACTIVATE_NOW; > > - switch (fb->format->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->format->depth); > > info->var.xres = fb_width; > info->var.yres = fb_height; > -- > 2.20.1 > -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch