Message-ID: <68708ef5-9a7f-b7e5-a7a0-e08f6d5ae3a3@collabora.com>
Date:   Wed, 15 Feb 2023 13:51:26 +0200
From:   Cristian Ciocaltea <cristian.ciocaltea@...labora.com>
To:     Emil Renner Berthing <emil.renner.berthing@...onical.com>
Cc:     Andrew Lunn <andrew@...n.ch>, Lee Jones <lee@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Emil Renner Berthing <kernel@...il.dk>,
        Conor Dooley <conor@...nel.org>,
        Palmer Dabbelt <palmer@...belt.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Giuseppe Cavallaro <peppe.cavallaro@...com>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>,
        Jose Abreu <joabreu@...opsys.com>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Richard Cochran <richardcochran@...il.com>,
        Sagar Kadam <sagar.kadam@...ive.com>,
        Yanhong Wang <yanhong.wang@...rfivetech.com>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        netdev@...r.kernel.org, linux-riscv@...ts.infradead.org,
        linux-stm32@...md-mailman.stormreply.com,
        linux-arm-kernel@...ts.infradead.org, kernel@...labora.com
Subject: Re: [PATCH 08/12] net: stmmac: Add glue layer for StarFive JH7100 SoC

On 2/15/23 13:20, Emil Renner Berthing wrote:
> On Wed, 15 Feb 2023 at 01:09, Cristian Ciocaltea
> <cristian.ciocaltea@...labora.com> wrote:
>>
>> On 2/11/23 18:11, Andrew Lunn wrote:
>>>> +
>>>> +#define JH7100_SYSMAIN_REGISTER28 0x70
>>>> +/* The value below is not a typo, just really bad naming by StarFive ¯\_(ツ)_/¯ */
>>>> +#define JH7100_SYSMAIN_REGISTER49 0xc8
>>>
>>> Seems like the comment should be one line earlier?
> 
> Well yes, the very generic register names are also bad, but this
> comment refers to the fact that it kind of makes sense that register
> 28 has the offset
>    28 * 4 bytes pr. register = 0x70
> ..but then register 49 is oddly out of place at offset 0xc8 instead of
>    49 * 4 bytes pr. register = 0xc4
> 
>>> There is value in basing the names on the datasheet, but you could
>>> append something meaningful on the end:
>>>
>>> #define JH7100_SYSMAIN_REGISTER49_DLYCHAIN 0xc8
>>
>> Unfortunately the JH7100 datasheet I have access to doesn't provide any
>> information regarding the SYSCTRL-MAINSYS related registers. Maybe Emil
>> could provide some details here?
> 
> This is reverse engineered from the auto generated headers in their u-boot:
> https://github.com/starfive-tech/u-boot/blob/JH7100_VisionFive_devel/arch/riscv/include/asm/arch-jh7100/syscon_sysmain_ctrl_macro.h
> 
> Christian, I'm happy that you're working on this, but mess like this
> and waiting for the non-coherent dma to be sorted is why I didn't send
> it upstream yet.

Thank you for clarifying this and for all the work you have done so far, 
Emil! If you don't mind, I would be glad to continue helping with this 
mainlining effort.

>>>> +    if (!of_property_read_u32(np, "starfive,gtxclk-dlychain", &gtxclk_dlychain)) {
>>>> +            ret = regmap_write(sysmain, JH7100_SYSMAIN_REGISTER49, gtxclk_dlychain);
>>>> +            if (ret)
>>>> +                    return dev_err_probe(dev, ret, "error selecting gtxclk delay chain\n");
>>>> +    }
>>>
>>> You should probably document that if starfive,gtxclk-dlychain is not
>>> found in the DT blob, the value for the delay chain is undefined.  It
>>> would actually be better to define it, set it to 0 for example. That
>>> way, you know you don't have any dependency on the bootloader for
>>> example.
>>
>> Sure, I will set it to 0.
>>
>>>
>>>        Andrew
>>
>> Thanks for reviewing,
>> Cristian
>>
>> _______________________________________________
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>> linux-riscv@...ts.infradead.org
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