Message-ID: <68708ef5-9a7f-b7e5-a7a0-e08f6d5ae3a3@collabora.com>
Date:   Wed, 15 Feb 2023 13:51:26 +0200
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Subject: Re: [PATCH 08/12] net: stmmac: Add glue layer for StarFive JH7100 SoC
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To:     Emil Renner Berthing <emil.renner.berthing@canonical.com>
Cc:     Andrew Lunn <andrew@lunn.ch>, Lee Jones <lee@kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Emil Renner Berthing <kernel@esmil.dk>,
        Conor Dooley <conor@kernel.org>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        Giuseppe Cavallaro <peppe.cavallaro@st.com>,
        Alexandre Torgue <alexandre.torgue@foss.st.com>,
        Jose Abreu <joabreu@synopsys.com>,
        Maxime Coquelin <mcoquelin.stm32@gmail.com>,
        Richard Cochran <richardcochran@gmail.com>,
        Sagar Kadam <sagar.kadam@sifive.com>,
        Yanhong Wang <yanhong.wang@starfivetech.com>,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        netdev@vger.kernel.org, linux-riscv@lists.infradead.org,
        linux-stm32@st-md-mailman.stormreply.com,
        linux-arm-kernel@lists.infradead.org, kernel@collabora.com
References: <20230211031821.976408-1-cristian.ciocaltea@collabora.com>
 <20230211031821.976408-9-cristian.ciocaltea@collabora.com>
 <Y+e+N/aiqCctIp6e@lunn.ch>
 <d1769dac-9e80-2f0d-6a5c-386ef70e1547@collabora.com>
 <CAJM55Z8Uq2ZU3KvJZKDLZUJDLEyvHjCRJKcYn5CAOR0c2rhT7Q@mail.gmail.com>
From:   Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
In-Reply-To: <CAJM55Z8Uq2ZU3KvJZKDLZUJDLEyvHjCRJKcYn5CAOR0c2rhT7Q@mail.gmail.com>
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On 2/15/23 13:20, Emil Renner Berthing wrote:
> On Wed, 15 Feb 2023 at 01:09, Cristian Ciocaltea
> <cristian.ciocaltea@collabora.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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