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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 D9B95C46CD2 for ; Tue, 9 Jan 2024 14:07:37 +0000 (UTC) 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:MIME-Version:Message-ID:In-reply-to: Date:Subject:Cc:To:From:References:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=LegRqrgxfp5GkXReLtHlF0/SnaFJFgJaGcKrpzxRu/Q=; b=KRP7bwLrJJnutr bZaFzQ4YLGE83HJJW5+TyuSRZx9yNlrGe7V4qHR0qyetlTPEqUqd3AhgDrlDqQubcSu04OJDh7vIS RPm0fjA5j2FDu1PW9L6z6Gcu18szYsbLy9GVcZA9oOch/7mmLN3z2StmrxDVN9T4wS8yj54VLAo1h PLU+e5qkmyvAVzl9ew4fuTki0BtujvT0vPb8hCwIiyg5hTv1tX+hZEkPmXuFOlEPLkxcQfcMnamfO XvtABAoajlIaWdBY3V5vBsvn+v5tNrX3FFW3s5UOZIGGfl/P65qMYFpdxGupCZ/zY26sJUwMgulvV MmKF5E2aIAoFeqsIiGJQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1rNCl0-008Tb6-0s; Tue, 09 Jan 2024 14:07:06 +0000 Received: from wiki.tkos.co.il ([84.110.109.230] helo=mail.tkos.co.il) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1rNCkw-008Ta4-2B for linux-arm-kernel@lists.infradead.org; Tue, 09 Jan 2024 14:07:04 +0000 Received: from localhost (unknown [10.0.8.2]) by mail.tkos.co.il (Postfix) with ESMTP id A125F4403F1; Tue, 9 Jan 2024 16:04:42 +0200 (IST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=tkos.co.il; s=default; t=1704809082; bh=nWkMWvzxZARucV9BKvxgMiKFVZFgW9ZAI35CPkgiN1w=; h=References:From:To:Cc:Subject:Date:In-reply-to:From; b=aAyidV3wDfegVJgn3hj2aDw+IJDBsWlDNykw4JwSxDMX60QxAwvxku7WYwfhglKQX 2r0YYJ4vBr+Je8oNZDOdl03Cx6gpEWss69lfGvbPCQRUa+su3KRCQ2L5JP5uk8NSsT gKR3SjuvtHwmVr93lXLKe85z8EGw5nJYRq2LITFBorKEpSQoWSM5eydLbl6TM5LuMc qXaOIwyps6aHgGJmM3j3vuH3oGosFp6h+DNn1Bl79twF0pH0Ke49ZYDFe/6A7k52C/ 2zLQhUqhtvbGT9bWpW1uWcR/oxlGh2ALKR9AqV8kfKCO+UVdQa2VwrxbqNbvbyDtKL AZGd+7diylz+Q== References: <87msterf7b.fsf@tarshish> User-agent: mu4e 1.10.8; emacs 29.1 From: Baruch Siach To: Catalin Marinas Cc: Christoph Hellwig , Marek Szyprowski , Rob Herring , Frank Rowand , Will Deacon , Robin Murphy , iommu@lists.linux.dev, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Petr =?utf-8?B?VGVzYcWZw61r?= , Ramon Fried , Elad Nachman Subject: Re: [PATCH RFC 3/4] dma-direct: add offset to zone_dma_bits Date: Tue, 09 Jan 2024 15:54:13 +0200 In-reply-to: Message-ID: <871qaqr477.fsf@tarshish> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240109_060703_183971_65EA0AB7 X-CRM114-Status: GOOD ( 19.98 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Catalin, On Tue, Jan 09 2024, Catalin Marinas wrote: > On Tue, Jan 09, 2024 at 12:03:43PM +0200, Baruch Siach wrote: >> On Mon, Jan 08 2024, Catalin Marinas wrote: >> > On Wed, Dec 27, 2023 at 05:04:27PM +0200, Baruch Siach wrote: >> >> Current code using zone_dma_bits assume that all addresses range in the >> >> bits mask are suitable for DMA. For some existing platforms this >> >> assumption is not correct. DMA range might have non zero lower limit. >> >> >> >> Add 'zone_dma_off' for platform code to set base address for DMA zone. >> >> >> >> Rename the dma_direct_supported() local 'min_mask' variable to better >> >> describe its use as limit. >> >> >> >> Suggested-by: Catalin Marinas >> > >> > When I suggested taking the DMA offsets into account, that's not exactly >> > what I meant. Based on patch 4, it looks like zone_dma_off is equivalent >> > to the lower CPU address. Let's say a system has DRAM starting at 2GB >> > and all 32-bit DMA-capable devices has a DMA offset of 0. We want >> > ZONE_DMA32 to end at 4GB rather than 6GB. >> >> Patch 4 sets zone_dma_off to the lower limit from 'dma-ranges' property >> that determines zone_dma_bits. This is not necessarily equivalent to >> start of DRAM, though it happens to be that way on my platform. > > A bit better but it still assumes that all devices have the same DMA > offset which may not be the case. Current code calculates zone_dma_bits based on the lowest high limit of all 'dma-ranges' properties. The assumption appears to be that this limit fits all devices. This series does not change this assumption. It only extends the logic to the lower limit of the "winning" 'dma-ranges' to set the base address for DMA zone. Moving to dma_zone_limit would not change that logic. Unless I'm missing something. Breaking the "one DMA zone fits all devices" assumption as Petr suggested is a much larger change. baruch -- ~. .~ Tk Open Systems =}------------------------------------------------ooO--U--Ooo------------{= - baruch@tkos.co.il - tel: +972.52.368.4656, http://www.tkos.co.il - _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel