From patchwork Tue Nov 3 09:27:33 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Thomas Gleixner X-Patchwork-Id: 11876879 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=-6.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 B1E93C388F7 for ; Tue, 3 Nov 2020 10:33:54 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 58A9722409 for ; Tue, 3 Nov 2020 10:33:54 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="otNm1FLh"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="aDUoEgUs" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 58A9722409 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linutronix.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=intel-gfx-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id C9D1F6EC6C; Tue, 3 Nov 2020 10:33:53 +0000 (UTC) Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) by gabe.freedesktop.org (Postfix) with ESMTPS id 34EE26EC6C; Tue, 3 Nov 2020 10:33:53 +0000 (UTC) Message-Id: <20201103095858.734064977@linutronix.de> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1604399629; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: references:references; bh=GQtIeN+bNrXtdDJbIY1/lT5u2Qlmlecyg45ylimAqeo=; b=otNm1FLhC7ruMh7oNXQtNETNU6+54RFk+t2LyeEF9d9+kDoZ9Kh8ZPgA+UB8A6JQ1ZXrGj 0TPeQl8iy37SQzf3hhxJ0YH8tjvvuOPaAqFoJKHafSPmEiutw0Ud/5TB6XtJVn4M9v5QlN Kc0YPCEkVxgY8QSHdaCi6xZgLgOgc1LgMVaGrZjI4AUGq0ZlUKuDX4Xk4y+i0m9xE3dk86 7GNBZMVBc/q+vRf7Zxdqgcl3bL7dPvuY81X2pyGhr1m48UNO2c+I7V2+wunozMP8FhvNCm gkFktETWxncmi0cgpUqLzaSL8knV0VimchG0Urhi5o5DvILy9hDHjs2CmUtXqQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1604399629; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: references:references; bh=GQtIeN+bNrXtdDJbIY1/lT5u2Qlmlecyg45ylimAqeo=; b=aDUoEgUsKRf0mAVHG33KZuw3tdfR+OUYkG1a4FnTBJVD3Vb06TvF7LUgRRezOsbA4xMida qFHqtJWvRi1kHPBw== Date: Tue, 03 Nov 2020 10:27:33 +0100 From: Thomas Gleixner To: LKML References: <20201103092712.714480842@linutronix.de> MIME-Version: 1.0 Subject: [Intel-gfx] [patch V3 21/37] Documentation/io-mapping: Remove outdated blurb X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Juri Lelli , linux-aio@kvack.org, Peter Zijlstra , Benjamin Herrenschmidt , Sebastian Andrzej Siewior , dri-devel@lists.freedesktop.org, virtualization@lists.linux-foundation.org, Ben Segall , Chris Mason , Huang Rui , Paul Mackerras , Gerd Hoffmann , Daniel Bristot de Oliveira , sparclinux@vger.kernel.org, Vincent Chen , Christoph Hellwig , Paul McKenney , Max Filippov , Michael Ellerman , x86@kernel.org, Russell King , linux-csky@vger.kernel.org, Ingo Molnar , David Airlie , VMware Graphics , Mel Gorman , nouveau@lists.freedesktop.org, Dave Airlie , linux-snps-arc@lists.infradead.org, Ben Skeggs , linux-xtensa@linux-xtensa.org, Arnd Bergmann , intel-gfx@lists.freedesktop.org, Roland Scheidegger , Josef Bacik , Steven Rostedt , Linus Torvalds , Alexander Viro , spice-devel@lists.freedesktop.org, David Sterba , Dietmar Eggemann , linux-arm-kernel@lists.infradead.org, Chris Zankel , Michal Simek , Thomas Bogendoerfer , Nick Hu , linux-mm@kvack.org, Vineet Gupta , linux-mips@vger.kernel.org, Christian Koenig , Benjamin LaHaise , linux-fsdevel@vger.kernel.org, Andrew Morton , linuxppc-dev@lists.ozlabs.org, "David S. Miller" , linux-btrfs@vger.kernel.org, Greentime Hu Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" The implementation details in the documentation are outdated and not really helpful. Remove them. Signed-off-by: Thomas Gleixner --- V3: New patch --- Documentation/driver-api/io-mapping.rst | 22 ---------------------- 1 file changed, 22 deletions(-) --- a/Documentation/driver-api/io-mapping.rst +++ b/Documentation/driver-api/io-mapping.rst @@ -73,25 +73,3 @@ for pages mapped with io_mapping_map_wc. At driver close time, the io_mapping object must be freed:: void io_mapping_free(struct io_mapping *mapping) - -Current Implementation -====================== - -The initial implementation of these functions uses existing mapping -mechanisms and so provides only an abstraction layer and no new -functionality. - -On 64-bit processors, io_mapping_create_wc calls ioremap_wc for the whole -range, creating a permanent kernel-visible mapping to the resource. The -map_atomic and map functions add the requested offset to the base of the -virtual address returned by ioremap_wc. - -On 32-bit processors with HIGHMEM defined, io_mapping_map_atomic_wc uses -kmap_atomic_pfn to map the specified page in an atomic fashion; -kmap_atomic_pfn isn't really supposed to be used with device pages, but it -provides an efficient mapping for this usage. - -On 32-bit processors without HIGHMEM defined, io_mapping_map_atomic_wc and -io_mapping_map_wc both use ioremap_wc, a terribly inefficient function which -performs an IPI to inform all processors about the new mapping. This results -in a significant performance penalty.