From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Arnd Bergmann" Subject: Re: [PATCH 00/12] arch,fbdev: Move screen_info into arch/ Date: Thu, 29 Jun 2023 16:42:42 +0200 Message-ID: References: <20230629121952.10559-1-tzimmermann@suse.de> <4d711508-c299-49f2-8691-e75d68f2485e@app.fastmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:Subject:Cc:To:From:Date:References: In-Reply-To:Message-Id:Mime-Version:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=GEM6r21sC2BoiZj7euPmUn+HDBNnR5OKeyfcBfy3wjg=; b=1W1FSC5wvtKhCo JyYCu5rlpVPcQRd5+cLHe3gzqp4o1VQh94DqmktxVYAwTpXqBBFvTIkhbZWxt6FRU0T2i8Hdz5M03 1v+bhZaZvulxQcUcmQu1MXqK7W6rloKGrFBfduF52wPeeRrm4TMK/MrqXXscISOImss8E3gaSb3ab 3CiqHvo8Dti5Bn/iCcGYbgqmzYawBHhCaWfbxJSqUHeUUrTSO/v+0sqHj1fEO0xxVTT8RpZz5SmH6 AG2Fx2+8LpbVV0a0rzyqdNjiM+dTEk4VkiIJkiHQZhmJzaSsKnuvmMqdWhQWg2TiEfEbxdYOK6afC 88N8x+w2O4mDZSaJBeUw==; DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=arndb.de; h=cc :cc:content-type:content-type:date:date:from:from:in-reply-to :in-reply-to:message-id:mime-version:references:reply-to:sender :subject:subject:to:to; s=fm1; t=1688049783; x=1688056983; bh=tH SCuJbmuJlT+unyX4wdwm35F06LE8SCy+Og6X/m9DI=; b=FV9nO/j/Xdm5cnG6UB sO9u8qjWkG4zOqKUhXnhJ2RYfN1MZ3Kurqn85lEsJl7vkP5a/wdBWaFdfq4uSulg eD/TXf6t4GqPVAoNus5HnjtbA1vX8VrBrjgri2vE0OiP2BSb5Sz/Pa2C0OcILLNa uvFS7KDmA3Z+PSTaIcpOvOnZyAi2yVT1FzCqp7iRvA0LJt1+wRraHFLOR3jih5Cs jATcgblkM7OGPteVBvXmW3paY0tjSC/B5Xw7fxmwX1f73RjswI9pT+zjkQRu+TqM Zsrmd0IqOKzH2xm5FLjlXxLg/SYtjqX8WBuItuEotXdBlqMlSIKnBw9uSc0kSFc4 WB+Q== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:cc:content-type:content-type:date:date :feedback-id:feedback-id:from:from:in-reply-to:in-reply-to :message-id:mime-version:references:reply-to:sender:subject :subject:to:to:x-me-proxy:x-me-proxy:x-me-sender:x-me-sender :x-sasl-enc; s=fm2; t=1688049783; x=1688056983; bh=tHSCuJbmuJlT+ unyX4wdwm35F06LE8SCy+Og6X/m9DI=; b=IEg6bOdqZ2fgoUmwXVc8pb/uyJ2CC MOuLn/CZcijB/QkegFpO4zpbp2YYMXm7i7Fu54Datj1E0vkDR3DKgAUxo6z+GWk3 vXwluBuok2nikCjYscmpRjVF9aIs6Z3Xj7fdUsirXf+m9AdUwVoMNKOO0MYZ2R8w hgGHbzL0Ar9zadbigZQorDDjOWkOiah/gEi8RJBLof77Nwpm9iJ+r3Tp7gQ7XU3u cozoUBEjOyE8ENgbEKdyPutCHcAWlVtfgQdZBYVqqbmbh2K14vwZE6PMJ4Kx6p2+ /+OkyxEaQgOqymqPNrwdxRUuj9S7LqeMaozoifwtEIa8O5rZRMCvumLJw== In-Reply-To: List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-riscv" Errors-To: linux-riscv-bounces+glpr-linux-riscv=m.gmane-mx.org@lists.infradead.org To: Thomas Zimmermann , Helge Deller , Daniel Vetter , Dave Airlie Cc: Linux-Arch , linux-hyperv@vger.kernel.org, linux-efi@vger.kernel.org, linux-ia64@vger.kernel.org, linux-sh@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-staging@lists.linux.dev, linux-kernel@vger.kernel.org, "linux-csky@vger.kernel.org" , linux-mips@vger.kernel.org, linux-fbdev@vger.kernel.org, dri-devel@lists.freedesktop.org, loongarch@lists.linux.dev, linux-alpha@vger.kernel.org, sparclinux@vger.kernel.org, linux-riscv@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, linux-arm-kernel@lists.infradead.org On Thu, Jun 29, 2023, at 16:15, Thomas Zimmermann wrote: > Am 29.06.23 um 15:31 schrieb Arnd Bergmann: >> On Thu, Jun 29, 2023, at 13:45, Thomas Zimmermann wrote: >>> Future directions: with the patchset in place, it will become possible >>> to provide screen_info and edid_info only if there are users. Some >>> architectures do this by testing for CONFIG_VT, CONFIG_DUMMY_CONSOLE, >>> etc. A more uniform approach would be nice. We should also attempt >>> to minimize access to the global screen_info as much as possible. To >>> do so, some drivers, such as efifb and vesafb, would require an update. >>> The firmware's EDID data could possibly made available outside of fbdev. >>> For example, the simpledrm and ofdrm drivers could provide such data >>> to userspace compositors. >> >> I suspect that most architectures that provide a screen_info only >> have this in order to compile the framebuffer drivers, and provide >> hardcoded data that does not even reflect any real hardware. > > That's quite possible. Only x86's bootparam and EFI code sets > screen_info from external data. The rest is hardcoded. A number of > architectures protect screen_info with CONFIG_VT, CONFIG_DUMMY_CONSOLE, > etc. In a later patchset, I wanted to change this such that these users > of screen_info would enable the feature via select in their Kconfig. > > Do you know the reason for this branch in dummycon: > > https://elixir.bootlin.com/linux/v6.4/source/drivers/video/console/dummycon.c#L21 > > What is special about arm that dummycon uses the screeninfo? I can only guess myself, but I see that the values are only ever set from the old ATAGS data, and not from DT on any of the modern ones, and my interpretation is that this is meant to match whatever the vga console was set to on the three platforms that support vgacon. I see this was added in linux-2.1.111, just before the corresponding sparc specific hack was removed, but I don't have patch descriptions from that era. Russell might remember, or know if that is actually still needed. Arnd