From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S932487AbdBPQNB (ORCPT <rfc822;w@1wt.eu>);
        Thu, 16 Feb 2017 11:13:01 -0500
Received: from mout.kundenserver.de ([212.227.126.130]:56918 "EHLO
        mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1754386AbdBPQM6 (ORCPT
        <rfc822;linux-kernel@vger.kernel.org>);
        Thu, 16 Feb 2017 11:12:58 -0500
From: Arnd Bergmann <arnd@arndb.de>
To: Nikita Yushchenko <nikita.yoush@cogentembedded.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will.deacon@arm.com>,
        linux-arm-kernel@lists.infradead.org,
        Simon Horman <horms@verge.net.au>, Bjorn Helgaas <bhelgaas@google.com>,
        linux-pci@vger.kernel.org, linux-renesas-soc@vger.kernel.org,
        artemi.ivanov@cogentembedded.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] arm64: dma_mapping: allow PCI host driver to limit DMA mask
Date: Thu, 29 Dec 2016 22:18:41 +0100
Message-ID: <2103911.qf9H68dkRp@wuerfel>
User-Agent: KMail/5.1.3 (Linux/4.4.0-34-generic; KDE/5.18.0; x86_64; ; )
In-Reply-To: <1483044304-2085-1-git-send-email-nikita.yoush@cogentembedded.com>
References: <1483044304-2085-1-git-send-email-nikita.yoush@cogentembedded.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 7Bit
Content-Type: text/plain; charset="us-ascii"
X-Provags-ID: V03:K0:+88f0UGmrguFsCou1jbn1At5dXLuvtbnDvQsq7mBwdGuc7EC73l
 5mPfWTfWIHHtbNDpEoYw+nlOGDkXaD1NO/Z5Mj0CLwpsGs4tqh9EF282Ifc16/0rwKZHG43
 sEBp09EnEzKbF+fRDym7YVcRDZ/TpGzmtGYkrsIS6W+P1Yq6Yr1nUd1Civ62eXUsQZ438/H
 Exx+dMvrdaT5TkComvXyw==
X-UI-Out-Filterresults: notjunk:1;V01:K0:bvoycw2bt5M=:h//IPSCLN/hzoteSLHs5SI
 c7S/7qosZFNswNokdJ2qgyOB1+a4ub5K3WQ1WzNvYKQ4wqomPa6RwUah6IPEheBUaZKSrZ0yn
 mTTkkehDW5FEK87x+Nkrjy9TicyXU9e7sXXh0i7UxrrGG90CUpqooifXwT7dWGuV9y4cjkTfg
 MgFup0OKSDs58FptXqv3MdS3ZzUSU1glp5H+LAwRm3jEIiUHCWg6ShGoi+C3XX3wt5Yc3rVz1
 r2ousEsrUnjx9pvmUPCYuC6UAnvnerJsXyXTx6niD+vxFdAtfwkGY+/g5BfJD9RYA8tB+8KGX
 eSQg+yNOML8x2j1qXcjXl9BqwCjuH3Ten/e8LjeY6cvc96oea1jZmreVeXgXa34722K98GOjd
 K2GHFJb3iRJKJB5bxi6rWd+A5zTfF0Fn1W4MBs2oP2YVzKVpoYj40K9ScwHuFXM9NpTaLWKPf
 /PgcNcrr9lgTA6fROiw++uSnd8wqYCGaGZNc5vbW47Ls+2Vmr6XJDvrT7VJkcIgCvSQO4QOl/
 2DYCG6eZr0/uD5Qpg7nxdAOXkuvi/rET5WyJa2fgrAOZVgD5q9zi9jnEnBlpvzclp0oL0uDVf
 NMrU7UrC6yAFjBt3EEDXOMhCqZMj6ixaHgvIVxaf7+JTd5dQ7656qvA4P/PPMBB6wLxA/cQba
 sfkVo+gYICCpEklml/9H+PKHmQUOM1jb6fHAEIePKcYIH61WR0NbY6iAnO5i0J51FQtpzA9Il
 293pQrxnmfZ4dzXY
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Thursday, December 29, 2016 11:45:03 PM CET Nikita Yushchenko wrote:
> 
>  static int __swiotlb_dma_supported(struct device *hwdev, u64 mask)
>  {
> +#ifdef CONFIG_PCI
> +       if (dev_is_pci(hwdev)) {
> +               struct pci_dev *pdev = to_pci_dev(hwdev);
> +               struct pci_host_bridge *br = pci_find_host_bridge(pdev->bus);
> +
> +               if (br->dev.dma_mask && (*br->dev.dma_mask) &&
> +                               (mask & (*br->dev.dma_mask)) != mask)
> +                       return 0;
> +       }
> +#endif
>         if (swiotlb)
>                 return swiotlb_dma_supported(hwdev, mask);
>         return 1;
> 

I think it's wrong to make this a special case for PCI.

Instead, we should follow the dma-ranges properties during dma_set_mask()
to ensure we don't set a mask that any of the parents up to the root
cannot support.

	Arnd