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=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 B7374C433DB for ; Sat, 16 Jan 2021 18:03:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 883F822510 for ; Sat, 16 Jan 2021 18:03:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727879AbhAPSDQ (ORCPT ); Sat, 16 Jan 2021 13:03:16 -0500 Received: from foss.arm.com ([217.140.110.172]:55786 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727226AbhAPSDQ (ORCPT ); Sat, 16 Jan 2021 13:03:16 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id C0947ED1; Sat, 16 Jan 2021 06:57:46 -0800 (PST) Received: from [10.57.56.43] (unknown [10.57.56.43]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 1BDB43F719; Sat, 16 Jan 2021 06:57:44 -0800 (PST) Subject: Re: [PATCH 1/2] of: device: Allow DMA range map to be set before of_dma_configure_id To: Paul Kocialkowski , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Cc: Jernej Skrabec , Daniel Vetter , Maxime Ripard , Chen-Yu Tsai , Rob Herring , Thomas Petazzoni , Frank Rowand References: <20210115175831.1184260-1-paul.kocialkowski@bootlin.com> From: Robin Murphy Message-ID: Date: Sat, 16 Jan 2021 14:57:43 +0000 User-Agent: Mozilla/5.0 (Windows NT 10.0; rv:78.0) Gecko/20100101 Thunderbird/78.6.1 MIME-Version: 1.0 In-Reply-To: <20210115175831.1184260-1-paul.kocialkowski@bootlin.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021-01-15 17:58, Paul Kocialkowski wrote: > A mechanism was recently introduced for the sunxi architecture where > the DMA offset for specific devices (under the MBUS) is set by a common > driver (sunxi_mbus). This driver calls dma_direct_set_offset to set > the device's dma_range_map manually. > > However this information was overwritten by of_dma_configure_id, which > obtains the map from of_dma_get_range (or keeps it NULL when it fails > and the force_dma argument is true, which is the case for platform > devices). > > As a result, the dma_range_map was always overwritten and the mechanism > could not correctly take effect. > > This adds a check to ensure that no previous DMA range map is > overwritten and prints a warning when the map was already set while > also being available from dt. In this case, the map that was already > set is kept. Hang on, the hard-coded offset is only intended to be installed when there *isn't* anything described in DT, in which case of_dma_get_range() should always bail out early without touching it anyway. This sounds like something's not quite right in the MBUS driver, so I don't think working around it in core code is really the right thing to do. Do you have a case where one of the relevant devices inherits a "dma-ranges" via the regular hierarchy without indirecting via an "interconnects" reference? Currently you're only checking for the latter, so that would be one way things could go awry (although to be a problem, said "dma-ranges" would also have to encode something *other* than the appropriate MBUS offset, which implies an incorrect or at least inaccurately-structured DT as well). Robin. > Fixes: b4bdc4fbf8d0 ("soc: sunxi: Deal with the MBUS DMA offsets in a central place") > Signed-off-by: Paul Kocialkowski > --- > drivers/of/device.c | 9 ++++++++- > 1 file changed, 8 insertions(+), 1 deletion(-) > > diff --git a/drivers/of/device.c b/drivers/of/device.c > index aedfaaafd3e7..db1b8634c2c7 100644 > --- a/drivers/of/device.c > +++ b/drivers/of/device.c > @@ -181,7 +181,14 @@ int of_dma_configure_id(struct device *dev, struct device_node *np, > > arch_setup_dma_ops(dev, dma_start, size, iommu, coherent); > > - dev->dma_range_map = map; > + if (!dev->dma_range_map) { > + dev->dma_range_map = map; > + } else if (map) { > + dev_warn(dev, > + "DMA range map was already set, ignoring range map from dt\n"); > + kfree(map); > + } > + > return 0; > } > EXPORT_SYMBOL_GPL(of_dma_configure_id); >