Date:   Sat, 8 Apr 2023 19:30:32 +0200
From:   Emil Renner Berthing <emil.renner.berthing@...onical.com>
To:     Guo Samin <samin.guo@...rfivetech.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

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.

> 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

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