On Mon, Feb 24, 2014 at 03:12:21PM +0000, srikanth TS wrote:
> Hi Will Deacon,
Hello,
> Currently SMMU driver expecting all stream ID used by respective master
> should be defined in the DT.
>
> We want to know how to handle in the case of virtual functions dynamically
> created and destroyed.
>
> Is PCI driver responsible for creating stream ID respective BDand
> requesting SMMU to add to the mapping table[stream Id to context mapping
> table]?
>
> Or is there any right way of doing it?
Correct, the driver currently doesn't support dynamic mappings (mainly
because I didn't want to try and invent something that I couldn't test).
There are a couple of ways to solve this:
(1) Add a way for a PCI RC to dynamically allocate StreamIDs on an SMMU
within a fixed range. That would probably need some code in the bus
layer, so that a bus notifier can kick and call back to the relevant
SMMU.
(2) Describe the RID -> SID mapping in the device-tree. We probably want
to avoid an enormous table, so this would only work for simple `SID =
RID + offset' or 'SID = RID & mask' cases.
How do your IDs map to each other?
Will
> -----Original Message-----
> From: [email protected] [mailto:iommu-
> [email protected]] On Behalf Of Will Deacon
> Sent: Monday, February 24, 2014 10:59 PM
> To: srikanth TS
> Cc: [email protected]; [email protected]; linux-
> [email protected]; [email protected]
> Subject: Re: your mail
>
> On Mon, Feb 24, 2014 at 03:12:21PM +0000, srikanth TS wrote:
> > Hi Will Deacon,
>
> Hello,
>
> > Currently SMMU driver expecting all stream ID used by respective
> > master should be defined in the DT.
> >
> > We want to know how to handle in the case of virtual functions
> > dynamically created and destroyed.
> >
> > Is PCI driver responsible for creating stream ID respective BDand
> > requesting SMMU to add to the mapping table[stream Id to context
> > mapping table]?
> >
> > Or is there any right way of doing it?
>
> Correct, the driver currently doesn't support dynamic mappings (mainly
> because I didn't want to try and invent something that I couldn't test).
>
> There are a couple of ways to solve this:
>
> (1) Add a way for a PCI RC to dynamically allocate StreamIDs on an SMMU
> within a fixed range. That would probably need some code in the bus
> layer, so that a bus notifier can kick and call back to the
> relevant
> SMMU.
This could be done in add device notifier. I am working on similar(not PCI) hot plug device infrastructure for arm smmu driver. I will post an RFC patch by next week.
-Varun