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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7FE6CC04A6A for ; Fri, 4 Aug 2023 20:55:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229464AbjHDUzs (ORCPT ); Fri, 4 Aug 2023 16:55:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56002 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229683AbjHDUzq (ORCPT ); Fri, 4 Aug 2023 16:55:46 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DEAE54C31; Fri, 4 Aug 2023 13:55:45 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 70FAD620E3; Fri, 4 Aug 2023 20:55:45 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 11BA5C433C7; Fri, 4 Aug 2023 20:55:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1691182544; bh=wReEdRZmNyzKl8e39OUS/Hxln9/SS8v2NW80Cb+MhRg=; h=In-Reply-To:References:Date:From:To:Cc:Subject:From; b=Dg2rKdsCZa9KopomzzcFwZJZVcIoYS0nwbd9LEhg5UBGsMLJciX8q4AFAGHVCtGrC P1nrcHCj2kqOfjWxuGs+6DImdGWftTInrnVWai2gagMhAs71O5JkmtftaoCtiDyu1z AERYu375lf1Pt0yYUcTHlMU9vRcscSn4K36Q5hKgxKT3iqopzNpmm1VOVPcSc2zVPv Zar+WBAKffJmB11lE1UcbucdfFdn9lwxZXodhjiOj84FicrvS5Cc1VUTfFQ9hMCtjl Q2yhSSSty8uLQxpxve0cM3XXCM2fXVihIfPTgeyh1hbBCk5xrbxB6yajkeC07Fnq3i PGtVzRLJge10A== Received: from compute6.internal (compute6.nyi.internal [10.202.2.47]) by mailauth.nyi.internal (Postfix) with ESMTP id DA8B427C0054; Fri, 4 Aug 2023 16:55:42 -0400 (EDT) Received: from imap51 ([10.202.2.101]) by compute6.internal (MEProxy); Fri, 04 Aug 2023 16:55:42 -0400 X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedviedrkeeggdduhedvucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmne cujfgurhepofgfggfkjghffffhvfevufgtsehttdertderredtnecuhfhrohhmpedftehr nhguuceuvghrghhmrghnnhdfuceorghrnhgusehkvghrnhgvlhdrohhrgheqnecuggftrf grthhtvghrnhepvdeviefgtedugeevieelvdfgveeuvdfgteegfeeiieejjeffgeeghedu gedtveehnecuvehluhhsthgvrhfuihiivgeptdenucfrrghrrghmpehmrghilhhfrhhomh eprghrnhguodhmvghsmhhtphgruhhthhhpvghrshhonhgrlhhithihqdduvdekhedujedt vdegqddvkeejtddtvdeigedqrghrnhgupeepkhgvrhhnvghlrdhorhhgsegrrhhnuggsrd guvg X-ME-Proxy: Feedback-ID: i36794607:Fastmail Received: by mailuser.nyi.internal (Postfix, from userid 501) id 3121EB60089; Fri, 4 Aug 2023 16:55:42 -0400 (EDT) X-Mailer: MessagingEngine.com Webmail Interface User-Agent: Cyrus-JMAP/3.9.0-alpha0-624-g7714e4406d-fm-20230801.001-g7714e440 Mime-Version: 1.0 Message-Id: <3baeb706-dc62-487c-a909-afc3cb3bed26@app.fastmail.com> In-Reply-To: References: <20230707095415.1449376-1-arnd@kernel.org> Date: Fri, 04 Aug 2023 22:55:20 +0200 From: "Arnd Bergmann" To: "Russell King" Cc: "Thomas Zimmermann" , "Javier Martinez Canillas" , linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, "Ard Biesheuvel" , "Helge Deller" , "Greg Kroah-Hartman" , "Arnd Bergmann" , "Paul Walmsley" , "Palmer Dabbelt" , "Albert Ou" , guoren , linux-riscv@lists.infradead.org, "linux-csky@vger.kernel.org" Subject: Re: [PATCH 1/4] vgacon: rework Kconfig dependencies Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-csky@vger.kernel.org On Tue, Aug 1, 2023, at 19:05, Russell King (Oracle) wrote: > On Fri, Jul 07, 2023 at 11:52:23AM +0200, Arnd Bergmann wrote: >> From: Arnd Bergmann >> >> The list of dependencies here is phrased as an opt-out, but this is missing >> a lot of architectures that don't actually support VGA consoles, and some >> of the entries are stale: >> >> - powerpc used to support VGA consoles in the old arch/ppc codebase, but >> the merged arch/powerpc never did >> >> - arm lists footbridge, integrator and netwinder, but netwinder is actually >> part of footbridge, and integrator does not appear to have an actual >> VGA hardware, or list it in its ATAG or DT. > > Integrator/AP has PCI, and I have had PCI VGA cards plugged in to that > hardware when I've had it. I'm pretty sure it can no longer work and broke a while ago, so I would prefer to leave it out unless someone actually has a reason to use it and puts the work in to restore the support. >From what I can tell, it's broken in at least three ways with the new PCI host driver: - the PCI memory space is identity mapped to its CPU physical address as of d3721efce22d1 ("ARM: dts: integratorap: Fix PCI windows"), which is generally better for compatibility with broken drivers that read the BAR directly, but it prevents memory mapped ISA-style devices including VGA text buffer. - vga_base is no longer set by the new PCI host driver, so any accesses to the text buffer just end up in user space memory at (__iomem*)0xb8000 - there is no DT binding for setting the global screen_info to whatever the boot firmware has initialized the VGA BIOS to, and the default 80x30 on Arm does not match the typical 80x25 text that would be set by the BIOS. > Provided any platform sets up PCI in a compatible way, and can run the > VGA's BIOS to initialise the card, then vgacon is supportable. It looks like only footbridge does at this point, all the other platforms would need to fix at least some of the three things I mentioned above, in particular plat-orion is the only thing setting vga_base but also has the identity map issue. My impression is that nobody has cared about vgacon on most Arm systems since it's harder to get working than fbcon with a native PCI driver (or the built-in pl110 on integrator) but also less useful. Arnd