Date:   Mon, 10 Apr 2023 16:29:10 +0800
From:   Guo Samin <samin.guo@...rfivetech.com>
To:     Emil Renner Berthing <emil.renner.berthing@...onical.com>,
        <Arun.Ramadoss@...rochip.com>
CC:     <linux-kernel@...r.kernel.org>, <linux-riscv@...ts.infradead.org>,
        <devicetree@...r.kernel.org>, <netdev@...r.kernel.org>,
        "David S . Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Emil Renner Berthing <kernel@...il.dk>,
        Pedro Moreira <pmmoreir@...opsys.com>,
        Richard Cochran <richardcochran@...il.com>,
        Conor Dooley <conor@...nel.org>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Andrew Lunn <andrew@...n.ch>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Peter Geis <pgwipeout@...il.com>,
        Yanhong Wang <yanhong.wang@...rfivetech.com>,
        Tommaso Merciai <tomm.merciai@...il.com>
Subject: Re: [-net-next v11 5/6] net: stmmac: Add glue layer for StarFive
 JH7110 SoC


Re: [-net-next v11 5/6] net: stmmac: Add glue layer for StarFive JH7110 SoC
From: Emil Renner Berthing <emil.renner.berthing@...onical.com>
to: Guo Samin <samin.guo@...rfivetech.com>
data: 2023/4/9

> On Sat, 8 Apr 2023 at 03:16, Guo Samin <samin.guo@...rfivetech.com> wrote:
>>
>>  Re: [-net-next v11 5/6] net: stmmac: Add glue layer for StarFive JH7110 SoC
>> From: Emil Renner Berthing <emil.renner.berthing@...onical.com>
>> to: Samin Guo <samin.guo@...rfivetech.com>
>> data: 2023/4/8
>>
>>> On Fri, 7 Apr 2023 at 13:05, Samin Guo <samin.guo@...rfivetech.com> wrote:
>>>>
>>>> This adds StarFive dwmac driver support on the StarFive JH7110 SoC.
>>>>
>>>> Tested-by: Tommaso Merciai <tomm.merciai@...il.com>
>>>> Co-developed-by: Emil Renner Berthing <kernel@...il.dk>
>>>> Signed-off-by: Emil Renner Berthing <kernel@...il.dk>
>>>> Signed-off-by: Samin Guo <samin.guo@...rfivetech.com>
>>>> ---
>>>>  MAINTAINERS                                   |   1 +
>>>>  drivers/net/ethernet/stmicro/stmmac/Kconfig   |  12 ++
>>>>  drivers/net/ethernet/stmicro/stmmac/Makefile  |   1 +
>>>>  .../ethernet/stmicro/stmmac/dwmac-starfive.c  | 123 ++++++++++++++++++
>>>>  4 files changed, 137 insertions(+)
>>>>  create mode 100644 drivers/net/ethernet/stmicro/stmmac/dwmac-starfive.c
>>>>
>>>> diff --git a/MAINTAINERS b/MAINTAINERS
>>>> index 6b6b67468b8f..46b366456cee 100644
>>>> --- a/MAINTAINERS
>>>> +++ b/MAINTAINERS
>>>> @@ -19910,6 +19910,7 @@ M:      Emil Renner Berthing <kernel@...il.dk>
>>>>  M:     Samin Guo <samin.guo@...rfivetech.com>
>>>>  S:     Maintained
>>>>  F:     Documentation/devicetree/bindings/net/starfive,jh7110-dwmac.yaml
>>>> +F:     drivers/net/ethernet/stmicro/stmmac/dwmac-starfive.c
>>>>
>>>>  STARFIVE JH7100 CLOCK DRIVERS
>>>>  M:     Emil Renner Berthing <kernel@...il.dk>
>>>> diff --git a/drivers/net/ethernet/stmicro/stmmac/Kconfig b/drivers/net/ethernet/stmicro/stmmac/Kconfig
>>>> index f77511fe4e87..5f5a997f21f3 100644
>>>> --- a/drivers/net/ethernet/stmicro/stmmac/Kconfig
>>>> +++ b/drivers/net/ethernet/stmicro/stmmac/Kconfig
>>>> @@ -165,6 +165,18 @@ config DWMAC_SOCFPGA
>>>>           for the stmmac device driver. This driver is used for
>>>>           arria5 and cyclone5 FPGA SoCs.
>>>>
>>>> +config DWMAC_STARFIVE
>>>> +       tristate "StarFive dwmac support"
>>>> +       depends on OF && (ARCH_STARFIVE || COMPILE_TEST)
>>>> +       select MFD_SYSCON
>>>> +       default m if ARCH_STARFIVE
>>>> +       help
>>>> +         Support for ethernet controllers on StarFive RISC-V SoCs
>>>> +
>>>> +         This selects the StarFive platform specific glue layer support for
>>>> +         the stmmac device driver. This driver is used for StarFive JH7110
>>>> +         ethernet controller.
>>>> +
>>>>  config DWMAC_STI
>>>>         tristate "STi GMAC support"
>>>>         default ARCH_STI
>>>> diff --git a/drivers/net/ethernet/stmicro/stmmac/Makefile b/drivers/net/ethernet/stmicro/stmmac/Makefile
>>>> index 057e4bab5c08..8738fdbb4b2d 100644
>>>> --- a/drivers/net/ethernet/stmicro/stmmac/Makefile
>>>> +++ b/drivers/net/ethernet/stmicro/stmmac/Makefile
>>>> @@ -23,6 +23,7 @@ obj-$(CONFIG_DWMAC_OXNAS)     += dwmac-oxnas.o
>>>>  obj-$(CONFIG_DWMAC_QCOM_ETHQOS)        += dwmac-qcom-ethqos.o
>>>>  obj-$(CONFIG_DWMAC_ROCKCHIP)   += dwmac-rk.o
>>>>  obj-$(CONFIG_DWMAC_SOCFPGA)    += dwmac-altr-socfpga.o
>>>> +obj-$(CONFIG_DWMAC_STARFIVE)   += dwmac-starfive.o
>>>>  obj-$(CONFIG_DWMAC_STI)                += dwmac-sti.o
>>>>  obj-$(CONFIG_DWMAC_STM32)      += dwmac-stm32.o
>>>>  obj-$(CONFIG_DWMAC_SUNXI)      += dwmac-sunxi.o
>>>> diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-starfive.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-starfive.c
>>>> new file mode 100644
>>>> index 000000000000..4963d4008485
>>>> --- /dev/null
>>>> +++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-starfive.c
>>>> @@ -0,0 +1,123 @@
>>>> +// SPDX-License-Identifier: GPL-2.0+
>>>> +/*
>>>> + * StarFive DWMAC platform driver
>>>> + *
>>>> + * Copyright (C) 2021 Emil Renner Berthing <kernel@...il.dk>
>>>> + * Copyright (C) 2022 StarFive Technology Co., Ltd.
>>>> + *
>>>> + */
>>>> +
>>>> +#include <linux/mfd/syscon.h>
>>>> +#include <linux/of_device.h>
>>>> +#include <linux/regmap.h>
>>>> +
>>>> +#include "stmmac_platform.h"
>>>> +
>>>> +struct starfive_dwmac {
>>>> +       struct device *dev;
>>>> +       struct clk *clk_tx;
>>>> +};
>>>> +
>>>> +static void starfive_dwmac_fix_mac_speed(void *priv, unsigned int speed)
>>>> +{
>>>> +       struct starfive_dwmac *dwmac = priv;
>>>> +       unsigned long rate;
>>>> +       int err;
>>>> +
>>>> +       rate = clk_get_rate(dwmac->clk_tx);
>>>
>>> Hi Samin,
>>>
>>> I'm not sure why you added this line in this revision. If it's just to
>>> not call clk_set_rate on the uninitialized rate, I'd much rather you
>>> just returned early and don't call clk_set_rate at all in case of
>>> errors.
>>>
>>>> +
>>>> +       switch (speed) {
>>>> +       case SPEED_1000:
>>>> +               rate = 125000000;
>>>> +               break;
>>>> +       case SPEED_100:
>>>> +               rate = 25000000;
>>>> +               break;
>>>> +       case SPEED_10:
>>>> +               rate = 2500000;
>>>> +               break;
>>>> +       default:
>>>> +               dev_err(dwmac->dev, "invalid speed %u\n", speed);
>>>> +               break;
>>>
>>> That is skip the clk_get_rate above and just change this break to a return.
>>>
>>
>> Hi Emil,
>>
>> We used the solution you mentioned before V3, but Arun Ramadoss doesn't think that's great.
>> (https://patchwork.kernel.org/project/linux-riscv/patch/20230106030001.1952-6-yanhong.wang@starfivetech.com)
>>
>>
>>> +static void starfive_eth_plat_fix_mac_speed(void *priv, unsigned int
>>> speed)
>>> +{
>>> +     struct starfive_dwmac *dwmac = priv;
>>> +     unsigned long rate;
>>> +     int err;
>>> +
>>> +     switch (speed) {
>>> +     case SPEED_1000:
>>> +             rate = 125000000;
>>> +             break;
>>> +     case SPEED_100:
>>> +             rate = 25000000;
>>> +             break;
>>> +     case SPEED_10:
>>> +             rate = 2500000;
>>> +             break;
>>> +     default:
>>> +             dev_err(dwmac->dev, "invalid speed %u\n", speed);
>>> +             return;
>>
>> Do we need to return value, since it is invalid speed. But the return
>> value of function is void.(Arun Ramadoss)
>>
>>
>> So in v9, after discussing with Jakub Kicinski, the clk_set_rate was used to initialize the rate.
>> (It is a reference to Intel's scheme:    dwmac-intel-plat.c: kmb_eth_fix_mac_speed)
>> (https://patchwork.kernel.org/project/linux-riscv/patch/20230328062009.25454-6-samin.guo@starfivetech.com)
>>
> 
> Yeah, I think this is a misunderstanding and Arun is considering if we
> ought to return the error which we can't without changing generic
> dwmac code, and Jakub is rightly concerned about using a local
> variable uninitialized. I don't think anyone is suggesting that
> getting the rate just to set it to the exact same value is better than
> just leaving the clock alone.
> 
HI Emil,

Yeah, return early saves time and code complexity, and seems like a good solution so Yanhong did the same before v3. (Jakub has suggested it before),
I wonder if Arun or other maintainers accept this solution or if there are other solutions?

Best regards,
Samin

>> Best regards,
>> Samin
>>>> +       }
>>>> +
>>>> +       err = clk_set_rate(dwmac->clk_tx, rate);
>>>> +       if (err)
>>>> +               dev_err(dwmac->dev, "failed to set tx rate %lu\n", rate);
>>>> +}
>>>> +
>>>> +static int starfive_dwmac_probe(struct platform_device *pdev)
>>>> +{
>>>> +       struct plat_stmmacenet_data *plat_dat;
>>  cons>> +       struct stmmac_resources stmmac_res;
>>>> +       struct starfive_dwmac *dwmac;
>>>> +       struct clk *clk_gtx;
>>>> +       int err;
>>>> +
>>>> +       err = stmmac_get_platform_resources(pdev, &stmmac_res);
>>>> +       if (err)
>>>> +               return dev_err_probe(&pdev->dev, err,
>>>> +                                    "failed to get resources\n");
>>>> +
>>>> +       plat_dat = stmmac_probe_config_dt(pdev, stmmac_res.mac);
>>>> +       if (IS_ERR(plat_dat))
>>>> +               return dev_err_probe(&pdev->dev, PTR_ERR(plat_dat),
>>>> +                                    "dt configuration failed\n");
>>>> +
>>>> +       dwmac = devm_kzalloc(&pdev->dev, sizeof(*dwmac), GFP_KERNEL);
>>>> +       if (!dwmac)
>>>> +               return -ENOMEM;
>>>> +
>>>> +       dwmac->clk_tx = devm_clk_get_enabled(&pdev->dev, "tx");
>>>> +       if (IS_ERR(dwmac->clk_tx))
>>>> +               return dev_err_probe(&pdev->dev, PTR_ERR(dwmac->clk_tx),
>>>> +                                    "error getting tx clock\n");
>>>> +
>>>> +       clk_gtx = devm_clk_get_enabled(&pdev->dev, "gtx");
>>>> +       if (IS_ERR(clk_gtx))
>>>> +               return dev_err_probe(&pdev->dev, PTR_ERR(clk_gtx),
>>>> +                                    "error getting gtx clock\n");
>>>> +
>>>> +       /* Generally, the rgmii_tx clock is provided by the internal clock,
>>>> +        * which needs to match the corresponding clock frequency according
>>>> +        * to different speeds. If the rgmii_tx clock is provided by the
>>>> +        * external rgmii_rxin, there is no need to configure the clock
>>>> +        * internally, because rgmii_rxin will be adaptively adjusted.
>>>> +        */
>>>> +       if (!device_property_read_bool(&pdev->dev, "starfive,tx-use-rgmii-clk"))
>>>> +               plat_dat->fix_mac_speed = starfive_dwmac_fix_mac_speed;
>>>> +
>>>> +       dwmac->dev = &pdev->dev;
>>>> +       plat_dat->bsp_priv = dwmac;
>>>> +       plat_dat->dma_cfg->dche = true;
>>>> +
>>>> +       err = stmmac_dvr_probe(&pdev->dev, plat_dat, &stmmac_res);
>>>> +       if (err) {
>>>> +               stmmac_remove_config_dt(pdev, plat_dat);
>>>> +               return err;
>>>> +       }
>>>> +
>>>> +       return 0;
>>>> +}
>>>> +
>>>> +static const struct of_device_id starfive_dwmac_match[] = {
>>>> +       { .compatible = "starfive,jh7110-dwmac" },
>>>> +       { /* sentinel */ }
>>>> +};
>>>> +MODULE_DEVICE_TABLE(of, starfive_dwmac_match);
>>>> +
>>>> +static struct platform_driver starfive_dwmac_driver = {
>>>> +       .probe  = starfive_dwmac_probe,
>>>> +       .remove = stmmac_pltfr_remove,
>>>> +       .driver = {
>>>> +               .name = "starfive-dwmac",
>>>> +               .pm = &stmmac_pltfr_pm_ops,
>>>> +               .of_match_table = starfive_dwmac_match,
>>>> +       },
>>>> +};
>>>> +module_platform_driver(starfive_dwmac_driver);
>>>> +
>>>> +MODULE_LICENSE("GPL");
>>>> +MODULE_DESCRIPTION("StarFive DWMAC platform driver");
>>>> +MODULE_AUTHOR("Emil Renner Berthing <kernel@...il.dk>");
>>>> +MODULE_AUTHOR("Samin Guo <samin.guo@...rfivetech.com>");
>>>> --
>>>> 2.17.1
>>>>
>>>>
>>>> _______________________________________________
>>>> linux-riscv mailing list
>>>> linux-riscv@...ts.infradead.org
>>>> http://lists.infradead.org/mailman/listinfo/linux-riscv
>>
>> --
>> Best regards,
>> Samin

-- 
Best regards,
Samin

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