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=-5.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 D2425C433E1 for ; Sat, 8 Aug 2020 06:39:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B3A2320855 for ; Sat, 8 Aug 2020 06:39:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726190AbgHHGd6 (ORCPT ); Sat, 8 Aug 2020 02:33:58 -0400 Received: from verein.lst.de ([213.95.11.211]:56035 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725786AbgHHGd6 (ORCPT ); Sat, 8 Aug 2020 02:33:58 -0400 Received: by verein.lst.de (Postfix, from userid 2407) id 3C5AB68C7B; Sat, 8 Aug 2020 08:33:55 +0200 (CEST) Date: Sat, 8 Aug 2020 08:33:54 +0200 From: Christoph Hellwig To: Nicolas Saenz Julienne Cc: Christoph Hellwig , amit.pundir@linaro.org, linux-kernel@vger.kernel.org, Marek Szyprowski , Robin Murphy , rientjes@google.com, jeremy.linton@arm.com, linux-rpi-kernel@lists.infradead.org, iommu@lists.linux-foundation.org Subject: Re: [PATCH v3 2/2] dma-pool: Only allocate from CMA when in same memory zone Message-ID: <20200808063354.GA17329@lst.de> References: <20200806184756.32075-1-nsaenzjulienne@suse.de> <20200806184756.32075-3-nsaenzjulienne@suse.de> <20200807052116.GA584@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Aug 07, 2020 at 10:50:19AM +0200, Nicolas Saenz Julienne wrote: > On Fri, 2020-08-07 at 07:21 +0200, Christoph Hellwig wrote: > > On Thu, Aug 06, 2020 at 08:47:55PM +0200, Nicolas Saenz Julienne wrote: > > > There is no guarantee to CMA's placement, so allocating a zone specific > > > atomic pool from CMA might return memory from a completely different > > > memory zone. To get around this double check CMA's placement before > > > allocating from it. > > > > As the builtbot pointed out, memblock_start_of_DRAM can't be used from > > non-__init code. But lookig at it I think throwing that in > > is bogus anyway, as cma_get_base returns a proper physical address > > already. > > It does indeed, but I'm comparing CMA's base with bitmasks that don't take into > account where the memory starts. Say memory starts at 0x80000000, and CMA falls > into ZONE_DMA [0x80000000 0xC0000000], if you want to compare it with > DMA_BIT_MASK(zone_dma_bits) you're forced to unify the memory bases. > > That said, I now realize that this doesn't work for ZONE_DMA32 which has a hard > limit on 32bit addresses reglardless of the memory base. > > That said I still need to call memblock_start_of_DRAM() any suggestions WRT > that? I could save the value in dma_atomic_pool_init(), which is __init code. The pool must be about a 32-bit physical address. The offsets can be different for every device..