linux-kernel - Re: [PATCH 16/20] dt-bindings: memory: snps: Detach Zynq DDRC controller support

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Message-ID: <166c0198-17c4-3b19-77fe-632d65f17cb0@linaro.org>
Date:   Tue, 23 Aug 2022 11:44:16 +0300
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Serge Semin <fancer.lancer@...il.com>
Cc:     Serge Semin <Sergey.Semin@...kalelectronics.ru>,
        Rob Herring <robh@...nel.org>,
        Michal Simek <michal.simek@...inx.com>,
        Borislav Petkov <bp@...en8.de>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Tony Luck <tony.luck@...el.com>,
        Rob Herring <robh+dt@...nel.org>,
        Manish Narani <manish.narani@...inx.com>,
        Alexey Malahov <Alexey.Malahov@...kalelectronics.ru>,
        Michail Ivanov <Michail.Ivanov@...kalelectronics.ru>,
        Pavel Parkhomenko <Pavel.Parkhomenko@...kalelectronics.ru>,
        Punnaiah Choudary Kalluri 
        <punnaiah.choudary.kalluri@...inx.com>,
        Dinh Nguyen <dinguyen@...nel.org>,
        James Morse <james.morse@....com>,
        Robert Richter <rric@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-edac@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 16/20] dt-bindings: memory: snps: Detach Zynq DDRC
 controller support

On 23/08/2022 11:32, Serge Semin wrote:
> On Tue, Aug 23, 2022 at 11:17:23AM +0300, Krzysztof Kozlowski wrote:
>> On 22/08/2022 22:07, Serge Semin wrote:
>>> The Zynq A05 DDRC controller has nothing in common with DW uMCTL2 DDRC:
>>> the CSRs layout is absolutely different and it doesn't has IRQ unlike DW
>>> uMCTL2 DDR controller of all versions (v1.x, v2.x and v3.x). Thus there is
>>> no any reason to have these controllers described by the same bindings.
>>> Thus let's split them up.
>>>
>>> While at it rename the original Synopsys uMCTL2 DT-schema file to a more
>>> descriptive - snps,dw-umctl2-ddrc.yaml and add a more detailed title and
>>> description of the device bindings.
>>
> 
>> Filename should be based on compatible, so if renaming then
>> snps,ddrc-3.80a.yaml or snps,ddrc.yaml... which leads to original
>> filename anyway. Therefore nack for rename.
> 
> New requirement? I've submitted not a single patch to the DT-bindings
> sources and didn't get any comment from Rob about that. 

This is not a new requirement. It has been since some time and Rob gave
such reviews.

https://lore.kernel.org/linux-devicetree/YlhkwvGdcf4ozTzG@robh.at.kernel.org/

For devices with multiple compatibles that's a bit tricky, but assuming
the bindings describe both original design from Synopsys and it's
implementations, then something closer to Synopsys makes sense.


> In addition
> There are DT bindings with names different from what is defined in the
> compatible name. Moreover there are tons of bindings with various
> compatible names. What name to choose then? Finally the current name
> is too generic to use for actual DW uMCTL2 DDRC controller.

There are thousands of bugs, inconsistencies, naming differences in
kernel. I don't find these as arguments to repeat the practice...so the
bindings file name should be based on the compatible.

Best regards,
Krzysztof