From: hdoyu@nvidia•com (Hiroshi Doyu)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH v5] devicetree: Add generic IOMMU device tree bindings
Date: Thu, 14 Aug 2014 19:04:52 +0300 [thread overview]
Message-ID: <87y4ur2h23.fsf@nvidia.com> (raw)
In-Reply-To: <cfb1d2ff66004685b7ead3f5e6321681@BL2PR03MB468.namprd03.prod.outlook.com>
Hi Varun,
Varun Sethi <Varun.Sethi@freescale•com> writes:
>> -----Original Message-----
>> From: iommu-bounces at lists.linux-foundation.org [mailto:iommu-
>> bounces at lists.linux-foundation.org] On Behalf Of Hiroshi Doyu
>> Sent: Thursday, August 14, 2014 12:18 PM
>> To: Thierry Reding; Stephen Warren; Arnd Bergmann; Will Deacon
>> Cc: Mark Rutland; devicetree at vger.kernel.org; Olof Johansson;
>> iommu at lists.linux-foundation.org; Rob Herring; linux-tegra at vger.kernel.org;
>> linux-arm-kernel at lists.infradead.org
>> Subject: Re: [PATCH v5] devicetree: Add generic IOMMU device tree bindings
>>
>>
>> Thierry Reding <thierry.reding@gmail•com> writes:
>>
>> > +Multiple-master IOMMU:
>> > +----------------------
>> > +
>> > + iommu {
>> > + /* the specifier represents the ID of the master */
>> > + #iommu-cells = <1>;
>> > + };
>> > +
>> > + master at 1 {
>> > + /* device has master ID 42 in the IOMMU */
>> > + iommus = <&{/iommu} 42>;
>> > + };
>> > +
>> > + master at 2 {
>> > + /* device has master IDs 23 and 24 in the IOMMU */
>> > + iommus = <&{/iommu} 23>, <&{/iommu} 24>;
>> > + };
>>
>> I think that this "master ID" will be parsed in IOMMU driver. For example,
>> ARM,SMMU expects "streamID" as "master ID", right?
>>
>> If a SoC has a feature to configure to assign streamID to devices at runtime,
>> "streamID" is not equal to "master ID".
>>
>> iommus = <&{/smmu} "soc specific master ID">;
>>
>> "soc master ID" needs to be translated into "streamID" by SoC SW. It seems
>> that ARM,SMMU kernel driver doesn't expect this kind of ID translation. If
>> ARM,SMMU kernel driver is used as is, "soc master ID"
>> would be incompatible? ARM,SMMU needs such translation before parsing. Is
>> this my understanding right?
>>
>> If so I think that this master ID configuration/translation may be quite
>> reasonable requirment for SoC using ARM,SMMU.
>>
>> Can we consider this ID translation within ARM,SMMU compatibility?
>>
>> IOW, is it possible to implement some SoC specific hook for ID
>> translation/configuration in ARM,SMMU kernel driver?
>
>
> Can the id translation be done using a SMR mask?
No, "SoC master ID" is completely independenf of SMR.
> 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.
next prev parent reply other threads:[~2014-08-14 16:04 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 [this message]
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
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=87y4ur2h23.fsf@nvidia.com \
--to=hdoyu@nvidia$(echo .)com \
--cc=linux-arm-kernel@lists$(echo .)infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox