[PATCH v4 08/13] iommu/rockchip: Control clocks needed to access the IOMMU

Randy Li randy.li at rock-chips.com
Thu Jan 25 01:42:17 PST 2018

On 01/22/2018 12:09 PM, JeffyChen wrote:
> Hi Randy,
> On 01/22/2018 10:15 AM, JeffyChen wrote:
>> Hi Randy,
>> On 01/22/2018 09:18 AM, Randy Li wrote:
>>> Also the power domain driver could manage the clocks as well, I would
>>> suggest to use pm_runtime_*.
>> actually the clocks required by pm domain may not be the same as what we
>> want to control here, there might be some clocks only be needed when
>> accessing mmu registers.
>> but i'm not very sure about that, will confirm it with Simon Xue.
> confirmed with Simon, there might be some iommus don't have a pd, and 
We use the pd to control the NIU node(not on upstream), without a pd or 
fake pd, none of the platform would work.
> the CONFIG_PM could be disabled.I am hard to believe a modern platform can work without that.
> so it might be better to control clocks in iommu driver itself.I won't insist how the version of the iommu patch on the upstream, I 
just post an idea here.
The version for kernel 4.4 is under internal review, the implementation 
has been modified many times.

I would suggest the managing clocks in pd is a more easy way and don't 
need to spare those thing in two places.
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Randy Li

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