linux-kernel - Re: [PATCH v5 1/3] dt-bindings: media: imx-jpeg: Assign slot for imx jpeg encoder/decoder

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Message-ID: <c2eb3a37-eadb-4ec6-a6c1-075d71127ac2@oss.nxp.com>
Date:   Thu, 19 Oct 2023 15:47:08 +0800
From:   ming qian <ming.qian@....nxp.com>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        mirela.rabulea@....nxp.com, robh+dt@...nel.org, shawnguo@...nel.org
Cc:     krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org,
        mchehab@...nel.org, hverkuil-cisco@...all.nl,
        s.hauer@...gutronix.de, kernel@...gutronix.de, festevam@...il.com,
        xiahong.bao@....com, eagle.zhou@....com, tao.jiang_2@....com,
        ming.qian@....com, linux-imx@....com, devicetree@...r.kernel.org,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v5 1/3] dt-bindings: media: imx-jpeg: Assign slot for imx
 jpeg encoder/decoder


Hi Krzysztof,

>> From: Ming Qian <ming.qian@....com>
>>
>> This IP includes a jpeg wrapper and a jpeg engine, the wrapper is
>> working on descriptor based manner. It supports up to 4 slots, each slot
>> can have its own chained descriptors. Host won't configure the engine
>> directly, but fill some descriptors to encode or decode one jpeg
>> picture. Then configure the descriptors to certain slot register. The
>> jpeg wrapper will schedule between different slots. When some slot is
>> finished, the slot interrupt will be triggered. The purpose of slot is
>> that engine can be shared across multiple VMS and os.
>>
>> Currently, power domains and interrupts are enabled for all 4 slots, but
>> only one slot is used. There is no benefit in using more that one slot
>> from within the same OS, as the slots are scheduled in round-robin
>> manner and not executed in parallel.
>>
>> Use the property "nxp,slot" to assign a single slot, and just expose the
>> parts of the h/w for the assigned slot. For example, only put slot 1's
>> power-domains entry in the DT when slot 1 is assigned. If not specified,
>> 0 is used by default.
>>
>> Signed-off-by: Ming Qian <ming.qian@....com>
>> ---
>> v5
>> - improve commit message
>> - improve property description
>>
>> v4
>> - improve commit message
>> - drop line making the property required, to avoid ABI break
>>
>> v3
>> - add vender prefix, change property slot to nxp,slot
>> - add type for property slot
>>
>> v2
>> - add a new property in bindings document
>>
>>   .../bindings/media/nxp,imx8-jpeg.yaml         | 46 +++++++++----------
>>   1 file changed, 22 insertions(+), 24 deletions(-)
>>
>> diff --git a/Documentation/devicetree/bindings/media/nxp,imx8-jpeg.yaml b/Documentation/devicetree/bindings/media/nxp,imx8-jpeg.yaml
>> index 3d9d1db37040..0961856bdcab 100644
>> --- a/Documentation/devicetree/bindings/media/nxp,imx8-jpeg.yaml
>> +++ b/Documentation/devicetree/bindings/media/nxp,imx8-jpeg.yaml
>> @@ -32,19 +32,27 @@ properties:
>>       maxItems: 1
>>   
>>     interrupts:
>> -    description: |
>> -      There are 4 slots available in the IP, which the driver may use
>> -      If a certain slot is used, it should have an associated interrupt
>> -      The interrupt with index i is assumed to be for slot i
>> -    minItems: 1               # At least one slot is needed by the driver
>> -    maxItems: 4               # The IP has 4 slots available for use
>> +    description:
>> +      Interrupt number for slot
>> +    maxItems: 1
> 
> The device still has four interrupts, so we should allow up to four of
> them. One given OS might want to use two or all four slots.
> 
> 
Got it, I will fix it in v6 patch.

>>   
>>     power-domains:
>>       description:
>>         List of phandle and PM domain specifier as documented in
>>         Documentation/devicetree/bindings/power/power_domain.txt
>> -    minItems: 2               # Wrapper and 1 slot
>> -    maxItems: 5               # Wrapper and 4 slots
>> +    minItems: 1               # Mixed power domain
>> +    maxItems: 2               # Wrapper and 1 slot
>> +
>> +  nxp,slot:
>> +    $ref: /schemas/types.yaml#/definitions/uint32
>> +    description:
>> +      Integer number of slot index used. This IP includes a jpeg wrapper, the
>> +      wrapper is working on descriptor based manner. It supports up to 4 slots,
>> +      each slot can have its own chained descriptors. The purpose is to share
>> +      the jpeg engine across multiple VMS and os. We use this property to
>> +      assign a single slot. If not specified, 0 is used by default.
>> +    minimum: 0
>> +    maximum: 3
> 
> default: 0
> 
Got it.

Best regards,
Ming
> 
> 
> Best regards,
> Krzysztof
>