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From: Thierry Reding <thierry.reding@gmail.com>
To: Joerg Roedel <joro@8bytes.org>
Cc: devicetree@vger.kernel.org, Frank Rowand <frowand.list@gmail.com>,
	Robin Murphy <robin.murphy@arm.com>,
	linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org,
	Rob Herring <robh+dt@kernel.org>, Will Deacon <will@kernel.org>
Subject: [PATCH v2 1/4] dt-bindings: reserved-memory: Document "active" property
Date: Fri,  4 Sep 2020 14:59:57 +0200	[thread overview]
Message-ID: <20200904130000.691933-1-thierry.reding@gmail.com> (raw)

From: Thierry Reding <treding@nvidia.com>

Reserved memory regions can be marked as "active" if hardware is
expected to access the regions during boot and before the operating
system can take control. One example where this is useful is for the
operating system to infer whether the region needs to be identity-
mapped through an IOMMU.

Signed-off-by: Thierry Reding <treding@nvidia.com>
---
 .../bindings/reserved-memory/reserved-memory.txt           | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt b/Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt
index 4dd20de6977f..163d2927e4fc 100644
--- a/Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt
+++ b/Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt
@@ -63,6 +63,13 @@ reusable (optional) - empty property
       able to reclaim it back. Typically that means that the operating
       system can use that region to store volatile or cached data that
       can be otherwise regenerated or migrated elsewhere.
+active (optional) - empty property
+    - If this property is set for a reserved memory region, it indicates
+      that some piece of hardware may be actively accessing this region.
+      Should the operating system want to enable IOMMU protection for a
+      device, all active memory regions must have been identity-mapped
+      in order to ensure that non-quiescent hardware during boot can
+      continue to access the memory.
 
 Linux implementation note:
 - If a "linux,cma-default" property is present, then Linux will use the
-- 
2.28.0

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             reply	other threads:[~2020-09-04 13:00 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-04 12:59 Thierry Reding [this message]
2020-09-04 12:59 ` [PATCH v2 2/4] iommu: Implement of_iommu_get_resv_regions() Thierry Reding
2020-09-04 12:59 ` [PATCH v2 3/4] iommu: dma: Use of_iommu_get_resv_regions() Thierry Reding
2020-09-04 13:00 ` [RFC 4/4] iommu/tegra-smmu: Add support for reserved regions Thierry Reding
2020-09-14 22:08 ` [PATCH v2 1/4] dt-bindings: reserved-memory: Document "active" property Rob Herring
2020-09-15 12:36   ` Thierry Reding
2020-09-24 11:27     ` Thierry Reding
2020-11-05 16:43       ` Thierry Reding
2020-11-05 17:47         ` Robin Murphy
2020-11-06 15:25           ` Thierry Reding
2020-11-10 19:33             ` Thierry Reding
2020-12-17 15:00               ` Thierry Reding
2020-12-18 22:15                 ` Rob Herring
2020-12-19  0:49                   ` Thierry Reding
2020-09-24 13:23 ` Dmitry Osipenko
2020-09-24 14:01   ` Thierry Reding
2020-09-24 16:23     ` Dmitry Osipenko
2020-09-25 12:39       ` Robin Murphy
2020-09-25 13:21         ` Dmitry Osipenko
2020-11-05 16:23           ` Thierry Reding
2020-09-25 13:52         ` Dmitry Osipenko
2020-11-05 15:57         ` Thierry Reding
2020-11-05 15:49       ` Thierry Reding
2021-01-12 19:00         ` Dmitry Osipenko

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