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Message-ID: <e5c72d2d-a1a1-40dd-103b-da7147b4e7ae@codeaurora.org>
Date: Fri, 31 Aug 2018 15:21:49 +0530
From: Vivek Gautam <vivek.gautam@...eaurora.org>
To: Rob Herring <robh@...nel.org>
Cc: Mark Rutland <mark.rutland@....com>, devicetree@...r.kernel.org,
alex.williamson@...hat.com,
"Rafael J. Wysocki" <rjw@...ysocki.net>,
Stephen Boyd <sboyd@...nel.org>,
freedreno <freedreno@...ts.freedesktop.org>,
"open list:THERMAL" <linux-pm@...r.kernel.org>,
Will Deacon <will.deacon@....com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Linux IOMMU <iommu@...ts.linux-foundation.org>,
linux-arm-msm <linux-arm-msm@...r.kernel.org>,
Andy Gross <andy.gross@...aro.org>,
Robin Murphy <robin.murphy@....com>
Subject: Re: [Patch v15 4/5] dt-bindings: arm-smmu: Add bindings for
qcom,smmu-v2
Hi Rob,
On 8/30/2018 6:13 AM, Rob Herring wrote:
> On Wed, Aug 29, 2018 at 6:23 AM Vivek Gautam
> <vivek.gautam@...eaurora.org> wrote:
>> On Wed, Aug 29, 2018 at 2:05 PM Vivek Gautam
>> <vivek.gautam@...eaurora.org> wrote:
>>> Hi Rob,
>>>
>>>
>>> On 8/29/2018 2:04 AM, Rob Herring wrote:
>>>> On Mon, Aug 27, 2018 at 04:25:50PM +0530, Vivek Gautam wrote:
>>>>> Add bindings doc for Qcom's smmu-v2 implementation.
>>>>>
>>>>> Signed-off-by: Vivek Gautam <vivek.gautam@...eaurora.org>
>>>>> Reviewed-by: Tomasz Figa <tfiga@...omium.org>
>>>>> Tested-by: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
>>>>> ---
>>>>>
>>>>> Changes since v14:
>>>>> - This is a new patch added in v15 after noticing the new
>>>>> checkpatch warning for separate dt-bindings doc.
>>>>> - This patch also addresses comments given by Rob and Robin to add
>>>>> a list of valid values of '<soc>' in "qcom,<soc>-smmu-v2"
>>>>> compatible string.
>>>>>
>>>>> .../devicetree/bindings/iommu/arm,smmu.txt | 47 ++++++++++++++++++++++
>>>>> 1 file changed, 47 insertions(+)
>>>>>
>>>>> diff --git a/Documentation/devicetree/bindings/iommu/arm,smmu.txt b/Documentation/devicetree/bindings/iommu/arm,smmu.txt
>>>>> index 8a6ffce12af5..52198a539606 100644
>>>>> --- a/Documentation/devicetree/bindings/iommu/arm,smmu.txt
>>>>> +++ b/Documentation/devicetree/bindings/iommu/arm,smmu.txt
>>>>> @@ -17,10 +17,24 @@ conditions.
>>>>> "arm,mmu-401"
>>>>> "arm,mmu-500"
>>>>> "cavium,smmu-v2"
>>>>> + "qcom,<soc>-smmu-v2", "qcom,smmu-v2"
>>>> The v2 in the compatible string is kind of redundant unless the SoC has
>>>> other SMMU types.
>>> sdm845 has smmu-v2, and smmu-500 [1].
>>>
>>>>> depending on the particular implementation and/or the
>>>>> version of the architecture implemented.
>>>>>
>>>>> + A number of Qcom SoCs use qcom,smmu-v2 version of the IP.
>>>>> + "qcom,<soc>-smmu-v2" represents a soc specific compatible
>>>>> + string that should be present along with the "qcom,smmu-v2"
>>>>> + to facilitate SoC specific clocks/power connections and to
>>>>> + address specific bug fixes.
>>>>> + '<soc>' string in "qcom,<soc>-smmu-v2" should be one of the
>>>>> + following:
>>>>> + msm8996 - for msm8996 Qcom SoC.
>>>>> + sdm845 - for sdm845 Qcom Soc.
>>>> Rather than all this prose, it would be simpler to just add 2 lines with
>>>> the full compatibles rather than <soc>. The <soc> thing is not going to
>>>> work when/if we move bindings to json-schema also.
>>> then we keep adding
>>> "qcom,msm8996-smmu-v2", "qcom,smmu-v2"
>>> "qcom,msm8998-smmu-v2", "qcom,smmu-v2"
>>> "qcom,sdm845-smmu-v2", "qcom,smmu-v2",
>>> and from [1]
>>> "qcom,sdm845-smmu-500", "arm,mmu-500", etc.
>>> for each SoCs?
>> How about following diff on top of this patch?
>>
>> diff --git a/Documentation/devicetree/bindings/iommu/arm,smmu.txt
>> b/Documentation/devicetree/bindings/iommu/arm,smmu.txt
>> index 52198a539606..5e6c04876533 100644
>> --- a/Documentation/devicetree/bindings/iommu/arm,smmu.txt
>> +++ b/Documentation/devicetree/bindings/iommu/arm,smmu.txt
>> @@ -17,23 +17,18 @@ conditions.
>> "arm,mmu-401"
>> "arm,mmu-500"
>> "cavium,smmu-v2"
>> - "qcom,<soc>-smmu-v2", "qcom,smmu-v2"
>> + "qcom,smmu-v2"
>>
>> depending on the particular implementation and/or the
>> version of the architecture implemented.
>>
>> - A number of Qcom SoCs use qcom,smmu-v2 version of the IP.
>> - "qcom,<soc>-smmu-v2" represents a soc specific compatible
>> - string that should be present along with the "qcom,smmu-v2"
>> - to facilitate SoC specific clocks/power connections and to
>> - address specific bug fixes.
>> - '<soc>' string in "qcom,<soc>-smmu-v2" should be one of the
>> - following:
>> - msm8996 - for msm8996 Qcom SoC.
>> - sdm845 - for sdm845 Qcom Soc.
>> -
>> - An example string would be -
>> - "qcom,msm8996-smmu-v2", "qcom,smmu-v2".
>> + Qcom SoCs using qcom,smmu-v2 must have soc specific
>> + compatible string attached to "qcom,smmu-v2" to take care
>> + of SoC specific clocks/power connections and to address
>> + specific bug fixes.
>> + Precisely, it should be one of the following:
>> + "qcom,msm8996-smmu-v2", "qcom,smmu-v2",
>> + "qcom,sdm845-smmu-v2", "qcom,smmu-v2".
> We don't need an explanation of why we need specific compatibles in
> each binding document (though maybe we need a better explanation
> somewhere). We just need to know what are valid values for compatibles
> and this includes any combinations. Generally, this is just a list of
> combinations.
[snip]
Fixed this in v16. Thanks.
Best regards
Vivek
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