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 S1031205AbbJ3VzV (ORCPT <rfc822;w@1wt.eu>);
	Fri, 30 Oct 2015 17:55:21 -0400
Received: from smtp.codeaurora.org ([198.145.29.96]:49782 "EHLO
	smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1030567AbbJ3VzS (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Fri, 30 Oct 2015 17:55:18 -0400
Subject: Re: [PATCH 2/2] dma: add Qualcomm Technologies HIDMA channel driver
To: Sinan Kaya <okaya@codeaurora.org>, Arnd Bergmann <arnd@arndb.de>
References: <1446174501-8870-1-git-send-email-okaya@codeaurora.org>
 <1446174501-8870-2-git-send-email-okaya@codeaurora.org>
 <5741892.rRLhcI7KQG@wuerfel> <5633E442.3010003@codeaurora.org>
Cc: dmaengine@vger.kernel.org, cov@codeaurora.org, jcm@redhat.com,
        Rob Herring <robh+dt@kernel.org>, Pawel Moll <pawel.moll@arm.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Ian Campbell <ijc+devicetree@hellion.org.uk>,
        Kumar Gala <galak@codeaurora.org>, Vinod Koul <vinod.koul@intel.com>,
        Dan Williams <dan.j.williams@intel.com>, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org
From: Timur Tabi <timur@codeaurora.org>
Message-ID: <5633E744.6040202@codeaurora.org>
Date: Fri, 30 Oct 2015 16:55:16 -0500
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101
 Thunderbird/38.3.0
MIME-Version: 1.0
In-Reply-To: <5633E442.3010003@codeaurora.org>
Content-Type: text/plain; charset=windows-1252; format=flowed
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On 10/30/2015 04:42 PM, Sinan Kaya wrote:
>>
>>     if (WARN_ON(!pdev->dev.dma_mask))
>>         return -ENXIO;
>>
>> The dma mask has to always be set by the platform code before probe()
>> is called. If it is not set, you are not allowed to perform DMA.
>
> I tested this on an ACPI platform BTW when I was working on the initial
> implementation.

PowerPC sets the mask to 32 bits by default:

http://lxr.free-electrons.com/ident?i=arch_setup_pdev_archdata

Should we do something similar in ARM64?  Today, we have to manually set 
the DMA mask in all drivers.

-- 
Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the
Code Aurora Forum, a Linux Foundation Collaborative Project.