From mboxrd@z Thu Jan  1 00:00:00 1970
From: m-karicheri2@ti.com (Murali Karicheri)
Date: Thu, 8 Jan 2015 17:46:31 -0500
Subject: [PATCH v3 0/4] PCI: get DMA configuration from parent device
In-Reply-To: <2785994.gTZ9chGdKf@wuerfel>
References: <1420656594-8908-1-git-send-email-m-karicheri2@ti.com>
 <54ADBB89.8070503@ti.com> <1934001.D0JfDRp1gF@wuerfel>
 <2785994.gTZ9chGdKf@wuerfel>
Message-ID: <54AF08C7.2010100@ti.com>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On 01/08/2015 05:27 PM, Arnd Bergmann wrote:
> On Thursday 08 January 2015 09:56:39 Arnd Bergmann wrote:
>> There is another interesting case, which is a USB host controller or
>> something similar behind a PCI bus. These are quite common and also
>> need to be handled in some form. Let's do just PCI first for now, but
>> be aware that this will come next. Should we assume that the ID that
>> is required for a device is either known from the device node, or
>> that it comes from a PCI device? That means for the USB case, we will
>> likely need to have some custom logic. There seems to be an implicit
>> assumption all over the kernel that all devices have the same IOMMU
>> instance, but we can't really rely on that here.
>>
>
> Update: I've checked the USB implementation and we are lucky because
> these interactions are all done by the USB host controller, and a
> USB device is not itself DMA capable. We don't have to do anything
> for USB.

Ok Thanks.

Murali
>
> 	Arnd
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-- 
Murali Karicheri
Linux Kernel, Texas Instruments