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Date:   Sat, 1 Apr 2023 01:09:42 +1000
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Subject: Re: [PATCH V3 7/7] arm64: dts: imx8mp: add interconnect for hsio blk
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To:     Ahmad Fatoum <a.fatoum@pengutronix.de>,
        Markus Niebel <Markus.Niebel@ew.tq-group.com>,
        Marco Felsch <m.felsch@pengutronix.de>
Cc:     peng.fan@nxp.com,
        Alexander Stein <alexander.stein@ew.tq-group.com>,
        abailon@baylibre.com, krzysztof.kozlowski+dt@linaro.org,
        festevam@gmail.com, abelvesa@kernel.org, marex@denx.de,
        paul.elder@ideasonboard.com, linux-imx@nxp.com,
        devicetree@vger.kernel.org,
        "Peng Fan (OSS)" <peng.fan@oss.nxp.com>, linux-pm@vger.kernel.org,
        s.hauer@pengutronix.de, robh+dt@kernel.org, aford173@gmail.com,
        "linux-arm-kernel@lists.infradead.org" 
        <linux-arm-kernel@lists.infradead.org>,
        laurent.pinchart@ideasonboard.com, linux-kernel@vger.kernel.org,
        kernel@pengutronix.de, djakov@kernel.org, shawnguo@kernel.org,
        l.stach@pengutronix.de
References: <20220703091451.1416264-8-peng.fan@oss.nxp.com>
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 <20230328073302.jj64u5hvdpc6axa5@pengutronix.de>
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 <20230328134201.yaxrdtetjygkgkmz@pengutronix.de>
 <20230328135100.rbmnfelphe7juhxo@pengutronix.de>
 <c368a0f8-41f0-69ac-04f4-459e5fc8b9d6@linux-m68k.org>
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 <809d5523-e0b4-cad4-f6ab-ddc0e4fe482d@pengutronix.de>
From:   Greg Ungerer <gerg@kernel.org>
In-Reply-To: <809d5523-e0b4-cad4-f6ab-ddc0e4fe482d@pengutronix.de>
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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
>>
>