linux-kernel - RE: [EXT] Re: [PATCH v4 1/2] arm64: dts: imx8-ss-img: Assign slot for imx jpeg encoder/decoder

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Date:   Thu, 28 Sep 2023 09:51:58 +0000
From:   Ming Qian <ming.qian@....com>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        "Mirela Rabulea (OSS)" <mirela.rabulea@....nxp.com>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "shawnguo@...nel.org" <shawnguo@...nel.org>
CC:     "krzysztof.kozlowski+dt@...aro.org" 
        <krzysztof.kozlowski+dt@...aro.org>,
        "conor+dt@...nel.org" <conor+dt@...nel.org>,
        "mchehab@...nel.org" <mchehab@...nel.org>,
        "hverkuil-cisco@...all.nl" <hverkuil-cisco@...all.nl>,
        "s.hauer@...gutronix.de" <s.hauer@...gutronix.de>,
        "kernel@...gutronix.de" <kernel@...gutronix.de>,
        "festevam@...il.com" <festevam@...il.com>,
        "X.H. Bao" <xiahong.bao@....com>, Eagle Zhou <eagle.zhou@....com>,
        Tao Jiang <tao.jiang_2@....com>,
        dl-linux-imx <linux-imx@....com>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-media@...r.kernel.org" <linux-media@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>
Subject: RE: [EXT] Re: [PATCH v4 1/2] arm64: dts: imx8-ss-img: Assign slot for
 imx jpeg encoder/decoder

>From: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
>Sent: 2023年9月28日 13:03
>To: Ming Qian <ming.qian@....com>; Mirela Rabulea (OSS)
><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; X.H. Bao
><xiahong.bao@....com>; Eagle Zhou <eagle.zhou@....com>; Tao Jiang
><tao.jiang_2@....com>; dl-linux-imx <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: [EXT] Re: [PATCH v4 1/2] arm64: dts: imx8-ss-img: Assign slot for
>imx jpeg encoder/decoder
>
>Caution: This is an external email. Please take care when clicking links or
>opening attachments. When in doubt, report the message using the 'Report
>this email' button
>
>
>On 27/09/2023 11:19, Ming Qian wrote:
>>> From: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
>>> Sent: 2023年9月27日 16:11
>>> To: Ming Qian <ming.qian@....com>; Mirela Rabulea (OSS)
>>> <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; X.H. Bao
>>> <xiahong.bao@....com>; Eagle Zhou <eagle.zhou@....com>; Tao Jiang
>>> <tao.jiang_2@....com>; dl-linux-imx <linux-imx@....com>;
>>> devicetree@...r.kernel.org; linux-media@...r.kernel.org; linux-
>>> kernel@...r.kernel.org; linux-arm-kernel@...ts.infradead.org
>>> Subject: [EXT] Re: [PATCH v4 1/2] arm64: dts: imx8-ss-img: Assign
>>> slot for imx jpeg encoder/decoder
>>>
>>> Caution: This is an external email. Please take care when clicking
>>> links or opening attachments. When in doubt, report the message using
>>> the 'Report this email' button
>>>
>>>
>>> On 26/09/2023 12:09, Ming Qian wrote:
>>>> There are total 4 slots available in the IP, and we only need to use
>>>> one slot in one os, assign a single slot for imx jpeg device node,
>>>> configure interrupt and power domain only for 1 slot, not for the all 4
>slots.
>>>
>>> DTS is independent of OS, so same DTS will be used by two OSes. This
>>> patch is not correct in that matter. Explanation is not proper justification.
>>>
>>
>> Hi Krzysztof,
>>
>> I agree that DTS is independent of OS, otherwise we need to choose the slot
>index by hard code in driver.
>> I think it's just the reason why we need this patch.
>> We have different platforms that use this IP, we need to configure the slot in
>dts.
>
>I still do not know what is the "slot". VM partitioning? Some pinmux
>configuration?
>
>Other platforms will use the same DTS, so the same slot and you are back at
>the same problem... DTS should be the full description of the hardware, thus
>removing interrupts is not "full description" anymore.
>

Hi Krzysztof,
    I have tried to explain the slot in the previous mail, although I'm not sure I made that clear. I think I need an example here. In our imx8q platform, we just want to assign slot 0 to linux, but in imx9 platform, we may want to assign slot 0 to linux, but slot 1 to a vm. So we don't want to enable power of slot 1 in linux.

Best regards,
Ming


>>
>> Would you please give some guide about proper justification?
>Describe architecture and then propose generic solution matching multiple
>vendors and IP blocks, not something solving only this one problem.
>
>Best regards,
>Krzysztof