From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-pci-owner@vger.kernel.org>
Received: from mail-wr0-f194.google.com ([209.85.128.194]:37352 "EHLO
        mail-wr0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1751288AbeFDVJo (ORCPT
        <rfc822;linux-pci@vger.kernel.org>); Mon, 4 Jun 2018 17:09:44 -0400
Subject: Re: [PATCH][RFC] PCI: rcar: Add bus notifier so we can limit the DMA
 range
To: Marek Vasut <marek.vasut@gmail.com>, Arnd Bergmann <arnd@arndb.de>
Cc: linux-pci <linux-pci@vger.kernel.org>,
        Phil Edworthy <phil.edworthy@renesas.com>,
        Marek Vasut <marek.vasut+renesas@gmail.com>,
        Geert Uytterhoeven <geert+renesas@glider.be>,
        Simon Horman <horms+renesas@verge.net.au>,
        Wolfram Sang <wsa@the-dreams.de>,
        Linux-Renesas <linux-renesas-soc@vger.kernel.org>,
        Nikita Yushchenko <nikita.yoush@cogentembedded.com>
References: <20180521220514.30256-1-marek.vasut+renesas@gmail.com>
 <CAK8P3a1PZ_MfgEcvWdUbN-eCcs5Xo38LQ54imLc4kNtSKO9Txw@mail.gmail.com>
 <c2897d82-fe33-52cd-5aa6-3bddb478cb9f@gmail.com>
From: Marek Vasut <marek.vasut@gmail.com>
Message-ID: <a40af3d8-83dc-ea5c-8a6f-f7bad9d40e58@gmail.com>
Date: Mon, 4 Jun 2018 23:09:40 +0200
MIME-Version: 1.0
In-Reply-To: <c2897d82-fe33-52cd-5aa6-3bddb478cb9f@gmail.com>
Content-Type: text/plain; charset=utf-8
Sender: linux-pci-owner@vger.kernel.org
List-ID: <linux-pci.vger.kernel.org>

On 05/22/2018 11:52 AM, Marek Vasut wrote:
> On 05/22/2018 10:10 AM, Arnd Bergmann wrote:
>> On Tue, May 22, 2018 at 12:05 AM, Marek Vasut <marek.vasut@gmail.com> wrote:
>>> From: Phil Edworthy <phil.edworthy@renesas.com>
>>>
>>> The PCIe DMA controller on RCar Gen2 and earlier is on 32bit bus,
>>> so limit the DMA range to 32bit.
>>>
>>> Signed-off-by: Phil Edworthy <phil.edworthy@renesas.com>
>>> Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
>>> Cc: Arnd Bergmann <arnd@arndb.de>
>>> Cc: Geert Uytterhoeven <geert+renesas@glider.be>
>>> Cc: Phil Edworthy <phil.edworthy@renesas.com>
>>> Cc: Simon Horman <horms+renesas@verge.net.au>
>>> Cc: Wolfram Sang <wsa@the-dreams.de>
>>> Cc: linux-renesas-soc@vger.kernel.org
>>> To: linux-pci@vger.kernel.org
>>> ---
>>> NOTE: I'm aware of https://patchwork.kernel.org/patch/9495895/ , but the
>>>       discussion seems to have gone way off, so I'm sending this as a
>>>       RFC. Any feedback on how to do this limiting properly would be nice.
>>
>> Doing it in the driver is clearly not appropriate, we must do this in
>> common code. If I remember correctly, it's specifically ARM64 that is
>> broken here, it incorrectly allows setting a DMA mask to 64 bit
>> when that is not available.
> 
> Yep, that's correct. ARM64 with devices mapping tremendous amounts of
> memory. So did anything change since that discussion references in the NOTE?

Bump ? I think it'd be nice to sort this out once and for all, since I
doubt it's just this controller that has such a limitation.

-- 
Best regards,
Marek Vasut