linux-kernel - Re: [PATCH V3 7/7] arm64: dts: imx8mp: add interconnect for hsio blk ctrl

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Message-ID: <e0631f32-832c-94a1-196c-dbaf41a4e68c@kernel.org>
Date:   Sat, 1 Apr 2023 01:09:42 +1000
From:   Greg Ungerer <gerg@...nel.org>
To:     Ahmad Fatoum <a.fatoum@...gutronix.de>,
        Markus Niebel <Markus.Niebel@...tq-group.com>,
        Marco Felsch <m.felsch@...gutronix.de>
Cc:     peng.fan@....com,
        Alexander Stein <alexander.stein@...tq-group.com>,
        abailon@...libre.com, krzysztof.kozlowski+dt@...aro.org,
        festevam@...il.com, abelvesa@...nel.org, marex@...x.de,
        paul.elder@...asonboard.com, linux-imx@....com,
        devicetree@...r.kernel.org,
        "Peng Fan (OSS)" <peng.fan@....nxp.com>, linux-pm@...r.kernel.org,
        s.hauer@...gutronix.de, robh+dt@...nel.org, aford173@...il.com,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        laurent.pinchart@...asonboard.com, linux-kernel@...r.kernel.org,
        kernel@...gutronix.de, djakov@...nel.org, shawnguo@...nel.org,
        l.stach@...gutronix.de
Subject: Re: [PATCH V3 7/7] arm64: dts: imx8mp: add interconnect for hsio blk
 ctrl



On 31/3/23 18:11, Ahmad Fatoum wrote:
> On 31.03.23 09:45, Markus Niebel wrote:
>> Am Freitag, dem 31.03.2023 um 15:55 +1000 schrieb Greg Ungerer:
>>> On 29/3/23 01:11, Marco Felsch wrote:
>>>> On 23-03-29, Greg Ungerer wrote:
>>> I agree this is the problem, I don't agree that the boot loader is
>>> the
>>> only place to fix this :-)  I should be able to generate a working
>>> devicetree
>>> blob from the kernel that is good, and ready to use no runtime
>>> changes
>>> required I figure.
>>>
>>
>> Just to point out: the approach of run time fixing in boot loader is
>> used for the other i.MX8M SOC, too. If you know exactly what SOC type
>> is assembled, you could disable non available IP in the board part of
>> your tree.
>>
>>> It is not overly difficult to break out the vpu nodes and have them
>>> only included when you have a board that has the iMX8MP-quad with the
>>> VPU hardware blocks.
> 
> This breaks out-of-tree DTs that include imx8mp.dtsi. Logic should be the
> other way round: imx8mp.dtsi is full-featured SoC and any new includes
> strip away, not add nodes.
> 
>> Depending on the SOC type there is more to look for than the VPU: core
>> count, ISP, NPU - just to mention a few. Current approach allows to
>> keep a single tree for all types.
> 
> +1.
> 
> @Greg, does your board always ship with an i.MX8MPLite? If so, just
> disable VPUs in your board DT.

Yes, it will only ever have the Lite. That is why I only want
to generate a devicetree blob without the VPU nodes.

Regards
Greg


> If it ships with either VPUs available or not and you don't want to do
> bootloader fixups, you may want to check out Kbuild's ability to apply
> DT overlays at build time. This would give you separate DTs for each
> variant while not having an extra file for every combination.
> 
> Cheers,
> Ahmad
> 
> 
>>
>> Regards, Markus
>>
>