From: hdoyu@nvidia•com (Hiroshi Doyu)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH v5] devicetree: Add generic IOMMU device tree bindings
Date: Tue, 19 Aug 2014 14:03:00 +0300 [thread overview]
Message-ID: <87wqa4hhcr.fsf@nvidia.com> (raw)
In-Reply-To: <a0244b6befa9407fb6c2c35cc29f92f7@BL2PR03MB468.namprd03.prod.outlook.com>
Varun Sethi <Varun.Sethi@freescale•com> writes:
>> >> > Also, for dynamic stream ID allocation we would need to represent
>> >> > the specific master register (to store the stream ID) in the device tree.
>> >>
>> >> I assmue that the above means that iMX has such configuration
>> >> register to map steramID and a device dynamically.
>> >
>> > We have per master registers for setting the stream ID on the
>> > Layerscape platforms. My point was that we would need the iommu master
>> > node to include a reference to the master id register.
>> >
>> > master at 1 {
>> > /* device has master ID 42 in the IOMMU */
>> > iommus = <&{/iommu} 42>;
>> > master-id-reg = <phandle offset> };
>>
>> In the above, for "iommus=" bindings, you wouldn't need to break
>> ARM,SMMU compatibility at all if you set "streamID" exactly as below.
>>
>> master at 1 {
>> /* device has master ID 42 in the IOMMU */
>> iommus = <&{/iommu} 'any given streamID'>;
>> master-id-reg = <phandle offset>
>> };
>>
>> And your SoC needs to register bus_notifier and ADD_DEVICE should configure
>> to map 'any given streamID' to a device via the above register. This wouldn't
>> need any modification from ARM,SMMU driver and keep the iommus bindings
>> as it is.
>>
>> IOW, SoC only needs to register ADD_DEVICE in bus_notifier to map StreamID
>> to a device. This needs to be executed earlier than IOMMU bus's ADD_DEVICE,
>> though.
>>
>> Is my understanding right?
>
> I don't think that SOC specific code needs a bus notifier for setting
> the stream ID. It can be done as a part of SOC specific
> initialization. The device tree can be updated to reflect the correct
> stream ID (SMMU driver can get the updated stream ID from device
> tree).
That's possible.
> I was thinking more on the lines of updating the device stream id
> while attaching a device to the domain.
I thought the same but this would break the ARM,SMMU /compatibility/
since the 1st param of "iommus=" is always expected as "streamID".
If streamID can be assigned dynamically like PCIe, not like streamID
statically set in DT, how should we describe this dynmaic steramID
shifting/assignment in DT?
next prev parent reply other threads:[~2014-08-19 11:03 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-07-31 10:43 [PATCH v5] devicetree: Add generic IOMMU device tree bindings Thierry Reding
2014-07-31 10:54 ` Mark Rutland
2014-07-31 12:04 ` Joerg Roedel
2014-07-31 15:38 ` Olof Johansson
2014-07-31 16:36 ` Joerg Roedel
2014-07-31 17:14 ` Olof Johansson
2014-07-31 17:23 ` Joerg Roedel
2014-07-31 18:09 ` Laurent Pinchart
2014-08-14 6:47 ` Hiroshi Doyu
2014-08-14 14:45 ` Varun Sethi
2014-08-14 16:04 ` Hiroshi Doyu
2014-08-19 9:52 ` Varun Sethi
2014-08-19 10:03 ` Hiroshi Doyu
2014-08-19 10:47 ` Varun Sethi
2014-08-19 11:03 ` Hiroshi Doyu [this message]
2014-08-19 12:01 ` Varun Sethi
2014-08-15 11:51 ` Will Deacon
2014-08-15 12:29 ` Hiroshi Doyu
2014-08-15 13:14 ` Will Deacon
2014-08-19 12:11 ` Varun Sethi
2014-08-22 15:33 ` Will Deacon
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