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 Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 0A49AC433EF for ; Fri, 4 Feb 2022 04:02:38 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id E996F10E1C6; Fri, 4 Feb 2022 04:02:37 +0000 (UTC) Received: from desiato.infradead.org (desiato.infradead.org [IPv6:2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by gabe.freedesktop.org (Postfix) with ESMTPS id 8D30610E1C6 for ; Fri, 4 Feb 2022 04:02:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=Content-Transfer-Encoding:Content-Type :In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date:Message-ID: Sender:Reply-To:Content-ID:Content-Description; bh=ZVHTl+4evudUQqpMq9P89GgpdyRepegfNHN+y+ufozM=; b=PhMZnmS9MMflO7XTDTvul9jZwH BsGLWg+k6Iy6lPO/8Ns/G6iAcg+4UHE9H0AuqXo3KJcsERpiTk0x87C+OcWGMObU7LUVfuv6mDqmo gFXrSaI96tk5dtodHNqG9r7fjIXUqtGRWUbTsHvpgQANN9AeyO51eyLHzCsPFxMTgGVs7efv9ZvTS xB4U2Q3Kk3EtbFpPRilzEUszV5mL0ZQMqIIUXouKIkBCeurAGWJPr4U4Sf8ogRVpFY20xqPX5E/sz aAYkUOieCK7hKYoBR8ydzu/JTNUkHBVR8p8cVELmLXXdAXmZvkpoxHPvaNISYq1GeWL2iDTgIC+JN rQva5CmQ==; Received: from [2601:1c0:6280:3f0::aa0b] by desiato.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1nFpng-006jPR-3N; Fri, 04 Feb 2022 04:02:20 +0000 Message-ID: <7ed6137e-cf19-3614-9404-e89389411a8f@infradead.org> Date: Thu, 3 Feb 2022 20:02:14 -0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.5.1 Subject: Re: Kconfig CONFIG_FB dependency regression Content-Language: en-US To: Thinh Nguyen , Arnd Bergmann References: <6fc4a81f-1a13-bff9-7b2e-d5bec382cb42@synopsys.com> <9bab4777-3034-b789-fdf6-ca8d7e6a8c35@infradead.org> <6743d6b1-13fe-9c83-f706-82338dd03897@synopsys.com> From: Randy Dunlap In-Reply-To: <6743d6b1-13fe-9c83-f706-82338dd03897@synopsys.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kees Cook , Daniel Vetter , "linux-kernel@vger.kernel.org" , "dri-devel@lists.freedesktop.org" , John Youn , Bing Yuan , "linux-mediatek@lists.infradead.org" , "linux-arm-kernel@lists.infradead.org" Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On 2/3/22 19:21, Thinh Nguyen wrote: > Arnd Bergmann wrote: >> On Thu, Feb 3, 2022 at 12:55 AM Thinh Nguyen wrote: >>> Arnd Bergmann wrote: >>>> On Wed, Feb 2, 2022 at 1:14 AM Thinh Nguyen wrote: >>>>> Fabio Estevam wrote: >>>> >>>> CONFIG_FB should not normally be needed for booting, so unless >>>> you have a graphical application in your initramfs that requires the /dev/fb0 >>>> device to work, it is not supposed to make a difference. >>>> >>> >>> I'm not sure, but it seems like the setup we have isn't the only one >>> that needed it. Fabio also noted that the imx_v6_v7_defconfig also needs >>> to have CONFIG_FB set. >> >> No, that one is different: the change for imx_v6_v7_defconfig was >> done because they actually use a framebuffer console on some devices, >> so the patch just adds the symbol to enable the drivers they are using. >> >> This is expected with my original patch that doesn't implicitly enable >> the framebuffer layer any more. What is not expected is for the kernel >> to hang during boot as you reported for your unidentified platform. >> >>>> Are there any other differences in your .config before and after the patch? >>>> It's possible that you use some other driver that in turn depends on >>>> CONFIG_FB. Does your machine have any graphical output device? >>>> If yes, which driver do you use? >>> >>> I don't have the answer to those questions yet. Need more investigation. >>> I'm new to this particular test setup. >> >> Do you mean you don't know if there is a screen attached to the system? >> > > It does have a graphical output device, but I didn't check what it is or > what driver is driving it. I just notice that after the reported commit, > something stopped working. > >>>> >>>> You may also want to make sure that you have 9d6366e743f3 ("drm: >>>> fb_helper: improve CONFIG_FB dependency") in your kernel, which >>>> fixes a minor problem with my original patch. >>>> >>> >>> The issue also occurs in mainline, which has your minor fix commit >>> above. The revert isn't clean for the latest kernel version. I also have >>> to revert some of the changes along with CONFIG_FB. The revert looks >>> more like this for the latest kernel: >>> >>> diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig >>> index b1f22e457fd0..7cbc733a8569 100644 >>> --- a/drivers/gpu/drm/Kconfig >>> +++ b/drivers/gpu/drm/Kconfig >>> @@ -118,8 +118,9 @@ config DRM_DEBUG_MODESET_LOCK >>> >>> config DRM_FBDEV_EMULATION >>> bool "Enable legacy fbdev support for your modesetting driver" >>> - depends on DRM_KMS_HELPER >>> - depends on FB=y || FB=DRM_KMS_HELPER >>> + depends on DRM >>> + select DRM_KMS_HELPER >>> + select FB >>> select FB_CFB_FILLRECT >>> select FB_CFB_COPYAREA >>> select FB_CFB_IMAGEBLIT >>> >>> >>> >>> I attached the configs for kernel v5.17-rc1. The "bad" config is without >>> any revert, the "good" config is with the change above. >> >> Looking at the config, I see that this is for an x86 machine, >> and you have the FB_EFI driver and EFI_EARLYCON enabled. >> >> What I suspec is going on is that you are looking at a screen rather >> than a serial console, and the kernel doesn't actually hang but you >> just don't see any more messages after the DRM driver takes >> over from EFI_EARLYCON because there is no console driver. >> >> In this case, what you see is the intended behavior, not a bug. >> If you want a graphical console in your system, you need to >> enable the support for this in your config. >> > > It sounds like that's the case. Unfortunately I'm not familiar with this > subsystem to say that's what happening. If there's nothing actually > broken from review, we can ignore this email thread. Hi, I don't know of anything that is broken... I am curious how CONFIG_FB_EFI came to be set when going from bad.config to good.config. Can you explain that? thanks. -- ~Randy