linux-kernel - Re: [PATCH 1/5] dt-bindings: media: mtk-vcodec: Add dma-ranges property

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Message-ID: <2b97b41c-d5d8-ac32-a9cf-c7bef09ed8ef@xs4all.nl>
Date:   Thu, 29 Apr 2021 13:15:57 +0200
From:   Hans Verkuil <hverkuil-cisco@...all.nl>
To:     Irui Wang <irui.wang@...iatek.com>, Rob Herring <robh@...nel.org>
Cc:     Alexandre Courbot <acourbot@...omium.org>,
        Tiffany Lin <tiffany.lin@...iatek.com>,
        Andrew-CT Chen <andrew-ct.chen@...iatek.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Fritz Koenig <frkoenig@...omium.org>,
        Tzung-Bi Shih <tzungbi@...omium.org>,
        Maoguang Meng <maoguang.meng@...iatek.com>,
        Longfei Wang <longfei.wang@...iatek.com>,
        Yunfei Dong <yunfei.dong@...iatek.com>,
        linux-media@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        srv_heupstream@...iatek.com, linux-mediatek@...ts.infradead.org
Subject: Re: [PATCH 1/5] dt-bindings: media: mtk-vcodec: Add dma-ranges
 property

Hi Rob,

On 01/03/2021 07:45, Irui Wang wrote:
> On Wed, 2021-02-10 at 16:53 -0600, Rob Herring wrote:
>> On Wed, Feb 03, 2021 at 04:37:48PM +0800, Irui Wang wrote:
>>> Adds dma-ranges property for DMA addresses translation.
>>>
>>> Signed-off-by: Irui Wang <irui.wang@...iatek.com>
>>> ---
>>>  Documentation/devicetree/bindings/media/mediatek-vcodec.txt | 2 ++
>>>  1 file changed, 2 insertions(+)
>>>
>>> diff --git a/Documentation/devicetree/bindings/media/mediatek-vcodec.txt b/Documentation/devicetree/bindings/media/mediatek-vcodec.txt
>>> index f85276e629bf..e4644f8caee9 100644
>>> --- a/Documentation/devicetree/bindings/media/mediatek-vcodec.txt
>>> +++ b/Documentation/devicetree/bindings/media/mediatek-vcodec.txt
>>> @@ -23,6 +23,8 @@ Required properties:
>>>  - iommus : should point to the respective IOMMU block with master port as
>>>    argument, see Documentation/devicetree/bindings/iommu/mediatek,iommu.txt
>>>    for details.
>>> +- dma-ranges : describes how the physical address space of the IOMMU maps
>>> +  to memory.
>>
>> dma-ranges is supposed to be in a bus/parent node.
> Dear Rob,
> 
> The mt8192 iommu support 0~16GB iova. We separate it to four banks:
> 0~4G; 4G~8G; 8G~12G; 12G~16G.
> 
> The "dma-ranges" could be used to adjust the bank we locate.
> If we don't set this property. The default range always is 0~4G.
> 
> Here we don't have actual bus/parent concept here.  And the iova
> requirement is for our HW. Thus put the property in our node.
> 
> Is this OK? If this is ok for you, I will put this message in the commit
> message and binding in next version.

Can you answer Irui's question? Just a reminder...

Much appreciated!

Regards,

	Hans

> 
> Regards
>>
>>>  One of the two following nodes:
>>>  - mediatek,vpu : the node of the video processor unit, if using VPU.
>>>  - mediatek,scp : the node of the SCP unit, if using SCP.
>>> -- 
>>> 2.25.1
>>>
>