Re: [PATCH v3 04/09] iommu/ipmmu-vmsa: Make use of IOMMU_OF_DECLARE()

From	Magnus Damm <magnus.damm@gmail.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH v3 04/09] iommu/ipmmu-vmsa: Make use of IOMMU_OF_DECLARE()
Date	2017-03-09 05:00 +0100
Message-ID	<tiXp7-7O0-3@gated-at.bofh.it> (permalink)
References	<tiHDH-5Js-3@gated-at.bofh.it> <tiI6K-5Wo-19@gated-at.bofh.it> <tiKie-7jK-29@gated-at.bofh.it>
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Hi Geert,

On Wed, Mar 8, 2017 at 10:52 PM, Geert Uytterhoeven
<geert@linux-m68k.org> wrote:
> Hi Magnus,
>
> On Wed, Mar 8, 2017 at 12:02 PM, Magnus Damm <magnus.damm@gmail.com> wrote:
>> From: Magnus Damm <damm+renesas@opensource.se>
>>
>> Hook up IOMMU_OF_DECLARE() support in case CONFIG_IOMMU_DMA
>> is enabled. The only current supported case for 32-bit ARM
>> is disabled, however for 64-bit ARM usage of OF is required.
>>
>> Signed-off-by: Magnus Damm <damm+renesas@opensource.se
>
> While I'm not such a big fan of *_OF_DECLARE() (it doesn't support deferred
> probing, which is needed for any device with dependencies, like clocks and
> power domains), what's the rationale for not using IOMMU_OF_DECLARE()
> on arm32, and thus the need for setup_done?

ARM32 could (and should) be converted over to IOMMU_OF_DECLARE(), but
it is just a matter of timing. If we try to do it before ARM32 is
converted over to CONFIG_IOMMU_DMA=y then we have to handle all the
hairy legacy implementation details of IOMMU support in case of
CONFIG_IOMMU_DMA=n _and_ deal with just moving over the init order
bits to OF. Testing and keeping all the combinations working is a lot
of work.

I prefer to kill two birds with one stone and do a larger feature jump
and move over ARM32 to same state of ARM64 (with OF init) once
CONFIG_IOMMU_DMA=y is ready for 32-bit ARM. Just changing the init
order bits to OF while keeping legacy CONFIG_IOMMU_DMA=n code is
introducing potential errors with not much upside. Unless there is
some other reason to do it that I can't see that is. =)

Cheers,

/ magnus

Thread

[PATCH v3 00/09] iommu/ipmmu-vmsa: r8a7795 support V3 Magnus Damm <magnus.damm@gmail.com> - 2017-03-08 12:10 +0100
  [PATCH v3 01/09] iommu/ipmmu-vmsa: Introduce features, break out alias Magnus Damm <magnus.damm@gmail.com> - 2017-03-08 12:10 +0100
    Re: [PATCH v3 01/09] iommu/ipmmu-vmsa: Introduce features, break out  alias Robin Murphy <robin.murphy@arm.com> - 2017-03-08 13:30 +0100
      Re: [PATCH v3 01/09] iommu/ipmmu-vmsa: Introduce features, break out alias Magnus Damm <magnus.damm@gmail.com> - 2017-03-09 05:30 +0100
  [PATCH v3 08/09] iommu/ipmmu-vmsa: Allow two bit SL0 Magnus Damm <magnus.damm@gmail.com> - 2017-03-08 12:20 +0100
  [PATCH v3 07/09] iommu/ipmmu-vmsa: Make IMBUSCTR setup optional Magnus Damm <magnus.damm@gmail.com> - 2017-03-08 12:20 +0100
  [PATCH v3 03/09] iommu/ipmmu-vmsa: Enable multi context support Magnus Damm <magnus.damm@gmail.com> - 2017-03-08 12:20 +0100
    Re: [PATCH v3 03/09] iommu/ipmmu-vmsa: Enable multi context support Robin Murphy <robin.murphy@arm.com> - 2017-03-08 14:10 +0100
      Re: [PATCH v3 03/09] iommu/ipmmu-vmsa: Enable multi context support Magnus Damm <magnus.damm@gmail.com> - 2017-03-09 05:20 +0100
  [PATCH v3 06/09] iommu/ipmmu-vmsa: Write IMCTR twice Magnus Damm <magnus.damm@gmail.com> - 2017-03-08 12:20 +0100
    Re: [PATCH v3 06/09] iommu/ipmmu-vmsa: Write IMCTR twice Robin Murphy <robin.murphy@arm.com> - 2017-03-08 13:40 +0100
      Re: [PATCH v3 06/09] iommu/ipmmu-vmsa: Write IMCTR twice Magnus Damm <magnus.damm@gmail.com> - 2017-03-09 05:00 +0100
  [PATCH v3 09/09] iommu/ipmmu-vmsa: Hook up r8a7795 DT matching code Magnus Damm <magnus.damm@gmail.com> - 2017-03-08 12:20 +0100
    Re: [PATCH v3 09/09] iommu/ipmmu-vmsa: Hook up r8a7795 DT matching code Geert Uytterhoeven <geert@linux-m68k.org> - 2017-03-08 15:10 +0100
      Re: [PATCH v3 09/09] iommu/ipmmu-vmsa: Hook up r8a7795 DT matching code Magnus Damm <magnus.damm@gmail.com> - 2017-03-09 05:30 +0100
  [PATCH v3 04/09] iommu/ipmmu-vmsa: Make use of IOMMU_OF_DECLARE() Magnus Damm <magnus.damm@gmail.com> - 2017-03-08 12:40 +0100
    Re: [PATCH v3 04/09] iommu/ipmmu-vmsa: Make use of IOMMU_OF_DECLARE() Geert Uytterhoeven <geert@linux-m68k.org> - 2017-03-08 15:00 +0100
      Re: [PATCH v3 04/09] iommu/ipmmu-vmsa: Make use of IOMMU_OF_DECLARE() Magnus Damm <magnus.damm@gmail.com> - 2017-03-09 05:00 +0100
  [PATCH v3 05/09] iommu/ipmmu-vmsa: IPMMU device is 40-bit bus master Magnus Damm <magnus.damm@gmail.com> - 2017-03-08 13:20 +0100

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