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Message-ID: <57f19774-39a1-03a6-fe68-83d7e4b16521@gmail.com>
Date:   Wed, 14 Sep 2022 10:13:51 -0700
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Subject: Re: [PATCH 16/21] dt-bindings: reserved-memory: introduce
 designated-movable-block
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To:     Rob Herring <robh@kernel.org>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Jonathan Corbet <corbet@lwn.net>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Frank Rowand <frowand.list@gmail.com>,
        Mike Kravetz <mike.kravetz@oracle.com>,
        Muchun Song <songmuchun@bytedance.com>,
        Mike Rapoport <rppt@kernel.org>,
        Christoph Hellwig <hch@lst.de>,
        Marek Szyprowski <m.szyprowski@samsung.com>,
        Robin Murphy <robin.murphy@arm.com>,
        Borislav Petkov <bp@suse.de>,
        "Paul E. McKenney" <paulmck@kernel.org>,
        Neeraj Upadhyay <quic_neeraju@quicinc.com>,
        Randy Dunlap <rdunlap@infradead.org>,
        Damien Le Moal <damien.lemoal@opensource.wdc.com>,
        Florian Fainelli <f.fainelli@gmail.com>,
        David Hildenbrand <david@redhat.com>, Zi Yan <ziy@nvidia.com>,
        Oscar Salvador <osalvador@suse.de>,
        Hari Bathini <hbathini@linux.ibm.com>,
        Kees Cook <keescook@chromium.org>,
        - <devicetree-spec@vger.kernel.org>,
        KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
        Mel Gorman <mgorman@suse.de>, linux-doc@vger.kernel.org,
        linux-kernel@vger.kernel.org, devicetree@vger.kernel.org,
        linux-mm@kvack.org, iommu@lists.linux.dev
References: <20220913195508.3511038-1-opendmb@gmail.com>
 <20220913195508.3511038-17-opendmb@gmail.com>
 <20220914145506.GA2149379-robh@kernel.org>
From:   Doug Berger <opendmb@gmail.com>
In-Reply-To: <20220914145506.GA2149379-robh@kernel.org>
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On 9/14/2022 7:55 AM, Rob Herring wrote:
> On Tue, Sep 13, 2022 at 12:55:03PM -0700, Doug Berger wrote:
>> Introduce designated-movable-block.yaml to document the
>> devicetree binding for Designated Movable Block children of the
>> reserved-memory node.
> 
> What is a Designated Movable Block? This patch needs to stand on its
> own.
As noted in my reply to your [PATCH 00/21] comment, my intention in 
submitting the entire patch set (and specifically PATCH 00/21]) was to 
communicate this context. Now that I believe I understand that only this 
patch should have been submitted to the devicetree-spec mailing list, I 
will strive harder to make it more self contained.

> 
> Why does this belong or need to be in DT?
While my preferred method of declaring Designated Movable Blocks is 
through the movablecore kernel parameter, I can conceive that others may 
wish to take advantage of the reserved-memory DT nodes. In particular, 
it has the advantage that a device can claim ownership of the 
reserved-memory via device tree, which is something that has yet to be 
implemented for DMBs defined with movablecore.

> 
>>
>> Signed-off-by: Doug Berger <opendmb@gmail.com>
>> ---
>>   .../designated-movable-block.yaml             | 51 +++++++++++++++++++
>>   1 file changed, 51 insertions(+)
>>   create mode 100644 Documentation/devicetree/bindings/reserved-memory/designated-movable-block.yaml
>>
>> diff --git a/Documentation/devicetree/bindings/reserved-memory/designated-movable-block.yaml b/Documentation/devicetree/bindings/reserved-memory/designated-movable-block.yaml
>> new file mode 100644
>> index 000000000000..42f846069a2e
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/reserved-memory/designated-movable-block.yaml
>> @@ -0,0 +1,51 @@
>> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
>> +%YAML 1.2
>> +---
>> +$id: http://devicetree.org/schemas/reserved-memory/designated-movable-block.yaml#
>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>> +
>> +title: /reserved-memory Designated Movable Block node binding
>> +
>> +maintainers:
>> +  - devicetree-spec@vger.kernel.org
>> +
>> +allOf:
>> +  - $ref: "reserved-memory.yaml"
>> +
>> +properties:
>> +  compatible:
>> +    const: designated-movable-block
>> +    description:
>> +      This indicates a region of memory meant to be placed into
>> +      ZONE_MOVABLE.
> 
> Don't put Linuxisms into bindings.
I will avoid ZONE_MOVABLE if this commit is included in V2 of this patch 
set.
> 
>> +
>> +unevaluatedProperties: false
>> +
>> +required:
>> +  - compatible
>> +  - reusable
>> +
>> +examples:
>> +  - |
>> +      reserved-memory {
>> +          #address-cells = <0x2>;
>> +          #size-cells = <0x2>;
>> +
>> +          DMB0@10800000 {
>> +               compatible = "designated-movable-block";
>> +               reusable;
>> +               reg = <0x0 0x10800000 0x0 0x2d800000>;
>> +          };
>> +
>> +          DMB1@40000000 {
>> +               compatible = "designated-movable-block";
>> +               reusable;
>> +               reg = <0x0 0x40000000 0x0 0x30000000>;
>> +          };
>> +
>> +          DMB2@80000000 {
>> +               compatible = "designated-movable-block";
>> +               reusable;
>> +               reg = <0x0 0x80000000 0x0 0x2fc00000>;
>> +          };
>> +      };
>> -- 
>> 2.25.1
>>
>>
Thank you for the review!
-Doug