RE: [EXT] Re: [PATCH v3 net 2/2] net: stmmac: dwmac-imx: pause the TXC clock in fixed-link

[Shenwei Wang]

> -----Original Message-----
> From: Johannes Zink <j.zink@xxxxxxxxxxxxxx>
> Sent: Wednesday, August 2, 2023 1:26 AM
> To: Shenwei Wang <shenwei.wang@xxxxxxx>; Russell King
> <linux@xxxxxxxxxxxxxxx>; David S. Miller <davem@xxxxxxxxxxxxx>; Eric
> Dumazet <edumazet@xxxxxxxxxx>; Jakub Kicinski <kuba@xxxxxxxxxx>; Paolo
> Abeni <pabeni@xxxxxxxxxx>; Maxime Coquelin
> <mcoquelin.stm32@xxxxxxxxx>; Shawn Guo <shawnguo@xxxxxxxxxx>; Sascha
> Hauer <s.hauer@xxxxxxxxxxxxxx>; Neil Armstrong <neil.armstrong@xxxxxxxxxx>;
> Kevin Hilman <khilman@xxxxxxxxxxxx>; Vinod Koul <vkoul@xxxxxxxxxx>; Chen-
> Yu Tsai <wens@xxxxxxxx>; Jernej Skrabec <jernej.skrabec@xxxxxxxxx>; Samuel
> Holland <samuel@xxxxxxxxxxxx>
> Cc: Giuseppe Cavallaro <peppe.cavallaro@xxxxxx>; Alexandre Torgue
> <alexandre.torgue@xxxxxxxxxxx>; Jose Abreu <joabreu@xxxxxxxxxxxx>;
> Pengutronix Kernel Team <kernel@xxxxxxxxxxxxxx>; Fabio Estevam
> <festevam@xxxxxxxxx>; dl-linux-imx <linux-imx@xxxxxxx>; Jerome Brunet
> <jbrunet@xxxxxxxxxxxx>; Martin Blumenstingl
> <martin.blumenstingl@xxxxxxxxxxxxxx>; Bhupesh Sharma
> <bhupesh.sharma@xxxxxxxxxx>; Nobuhiro Iwamatsu
> <nobuhiro1.iwamatsu@xxxxxxxxxxxxx>; Simon Horman
> <simon.horman@xxxxxxxxxxxx>; Andrew Halaney <ahalaney@xxxxxxxxxx>;
> Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxx>; Wong Vee Khee
> <veekhee@xxxxxxxxx>; Revanth Kumar Uppala <ruppala@xxxxxxxxxx>; Jochen
> Henneberg <jh@xxxxxxxxxxxxxxxxxxxxxxxxxx>; netdev@xxxxxxxxxxxxxxx; linux-
> stm32@xxxxxxxxxxxxxxxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx;
> linux-kernel@xxxxxxxxxxxxxxx; linux-amlogic@xxxxxxxxxxxxxxxxxxx;
> imx@xxxxxxxxxxxxxxx; Frank Li <frank.li@xxxxxxx>
> Subject: Re: [EXT] Re: [PATCH v3 net 2/2] net: stmmac: dwmac-imx: pause the
> TXC clock in fixed-link
>
> Caution: This is an external email. Please take care when clicking links or
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>
> Hi Shenwei,
>
> On 8/1/23 19:10, Shenwei Wang wrote:
> >
> >
> >> -----Original Message-----
> >> From: Johannes Zink <j.zink@xxxxxxxxxxxxxx>
> >> Sent: Tuesday, August 1, 2023 7:48 AM
> >> To: Shenwei Wang <shenwei.wang@xxxxxxx>; Russell King
> >> <linux@xxxxxxxxxxxxxxx>; David S. Miller <davem@xxxxxxxxxxxxx>; Eric
> >> Dumazet <edumazet@xxxxxxxxxx>; Jakub Kicinski <kuba@xxxxxxxxxx>;
> >> Paolo Abeni <pabeni@xxxxxxxxxx>; Maxime Coquelin
> >> <mcoquelin.stm32@xxxxxxxxx>; Shawn Guo <shawnguo@xxxxxxxxxx>;
> Sascha
> >> Hauer <s.hauer@xxxxxxxxxxxxxx>; Neil Armstrong
> >> <neil.armstrong@xxxxxxxxxx>; Kevin Hilman <khilman@xxxxxxxxxxxx>;
> >> Vinod Koul <vkoul@xxxxxxxxxx>; Chen- Yu Tsai <wens@xxxxxxxx>; Jernej
> >> Skrabec <jernej.skrabec@xxxxxxxxx>; Samuel Holland
> >> <samuel@xxxxxxxxxxxx>
> >> Cc: Giuseppe Cavallaro <peppe.cavallaro@xxxxxx>; Alexandre Torgue
> >> <alexandre.torgue@xxxxxxxxxxx>; Jose Abreu <joabreu@xxxxxxxxxxxx>;
> >> Pengutronix Kernel Team <kernel@xxxxxxxxxxxxxx>; Fabio Estevam
> >> <festevam@xxxxxxxxx>; dl-linux-imx <linux-imx@xxxxxxx>; Jerome Brunet
> >> <jbrunet@xxxxxxxxxxxx>; Martin Blumenstingl
> >> <martin.blumenstingl@xxxxxxxxxxxxxx>; Bhupesh Sharma
> >> <bhupesh.sharma@xxxxxxxxxx>; Nobuhiro Iwamatsu
> >> <nobuhiro1.iwamatsu@xxxxxxxxxxxxx>; Simon Horman
> >> <simon.horman@xxxxxxxxxxxx>; Andrew Halaney <ahalaney@xxxxxxxxxx>;
> >> Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxx>; Wong Vee Khee
> >> <veekhee@xxxxxxxxx>; Revanth Kumar Uppala <ruppala@xxxxxxxxxx>;
> >> Jochen Henneberg <jh@xxxxxxxxxxxxxxxxxxxxxxxxxx>;
> >> netdev@xxxxxxxxxxxxxxx; linux- stm32@xxxxxxxxxxxxxxxxxxxxxxxxxxxx;
> >> linux-arm-kernel@xxxxxxxxxxxxxxxxxxx;
> >> linux-kernel@xxxxxxxxxxxxxxx; linux-amlogic@xxxxxxxxxxxxxxxxxxx;
> >> imx@xxxxxxxxxxxxxxx; Frank Li <frank.li@xxxxxxx>
> >> Subject: [EXT] Re: [PATCH v3 net 2/2] net: stmmac: dwmac-imx: pause
> >> the TXC clock in fixed-link
> >>
> >> Caution: This is an external email. Please take care when clicking
> >> links or opening attachments. When in doubt, report the message using
> >> the 'Report this email' button
> >>
> >>
> >> Hi Shenwei,
> >>
> >> thanks for your patch.
> >>
> >> On 7/31/23 18:19, Shenwei Wang wrote:
> >>> When using a fixed-link setup, certain devices like the SJA1105
> >>> require a small pause in the TXC clock line to enable their internal
> >>> tunable delay line (TDL).
> >>
> >> If this is only required for some devices, is it safe to enforce this
> >> behaviour unconditionally for any kind of fixed link devices
> >> connected to the MX93 EQOS or could this possibly break for other devices?
> >>
> >
> > It won't impact normal devices. The link layer hasn't built up yet.
> >
>
> As Russel suggested in [1] - maybe you could rephrase your commit message for
> your v4 to point this out to future reviewers (apparently multiple people have
> had questions about this...)  and have this fact also recorded in the git log later
> on.
>

Okay.

> Also: does this only apply to i.MX93, or would we have to test and enable it on
> e.g. i.MX8MP as well?
>

Yes, it is required when the EQOS MAC is selected. However, this patch just enables
The feature on i.MX93.

Thanks,
Shenwei

> Thanks
> Johannes
>
> [1] ZMk/xqRP67zXHNrf@xxxxxxxxxxxxxxxxxxxxx
>
>
> > Thanks,
> > Shenwei
> >
> >> Best regards
> >> Johannes
> >>
> >>>
> >>> To satisfy this requirement, this patch temporarily disables the TX
> >>> clock, and restarts it after a required period. This provides the
> >>> required silent interval on the clock line for SJA1105 to complete
> >>> the frequency transition and enable the internal TDLs.
> >>>
> >>> So far we have only enabled this feature on the i.MX93 platform.
> >>>
> >>> Signed-off-by: Shenwei Wang <shenwei.wang@xxxxxxx>
> >>> Reviewed-by: Frank Li <frank.li@xxxxxxx>
> >>> ---
> >>>    .../net/ethernet/stmicro/stmmac/dwmac-imx.c   | 42
> +++++++++++++++++++
> >>>    1 file changed, 42 insertions(+)
> >>>
> >>> diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-imx.c
> >>> b/drivers/net/ethernet/stmicro/stmmac/dwmac-imx.c
> >>> index 53ee5a42c071..2e4173d099f3 100644
> >>> --- a/drivers/net/ethernet/stmicro/stmmac/dwmac-imx.c
> >>> +++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-imx.c
> >>> @@ -32,6 +32,7 @@
> >>>    #define GPR_ENET_QOS_RGMII_EN               (0x1 << 21)
> >>>
> >>>    #define MX93_GPR_ENET_QOS_INTF_MODE_MASK    GENMASK(3, 0)
> >>> +#define MX93_GPR_ENET_QOS_INTF_MASK          GENMASK(3, 1)
> >>>    #define MX93_GPR_ENET_QOS_INTF_SEL_MII              (0x0 << 1)
> >>>    #define MX93_GPR_ENET_QOS_INTF_SEL_RMII             (0x4 << 1)
> >>>    #define MX93_GPR_ENET_QOS_INTF_SEL_RGMII    (0x1 << 1)
> >>> @@ -40,6 +41,7 @@
> >>>    #define DMA_BUS_MODE                        0x00001000
> >>>    #define DMA_BUS_MODE_SFT_RESET              (0x1 << 0)
> >>>    #define RMII_RESET_SPEED            (0x3 << 14)
> >>> +#define CTRL_SPEED_MASK                      GENMASK(15, 14)
> >>>
> >>>    struct imx_dwmac_ops {
> >>>        u32 addr_width;
> >>> @@ -56,6 +58,7 @@ struct imx_priv_data {
> >>>        struct regmap *intf_regmap;
> >>>        u32 intf_reg_off;
> >>>        bool rmii_refclk_ext;
> >>> +     void __iomem *base_addr;
> >>>
> >>>        const struct imx_dwmac_ops *ops;
> >>>        struct plat_stmmacenet_data *plat_dat; @@ -212,6 +215,42 @@
> >>> static void imx_dwmac_fix_speed(void *priv, uint speed, uint mode)
> >>>                dev_err(dwmac->dev, "failed to set tx rate %lu\n", rate);
> >>>    }
> >>>
> >>> +static void imx_dwmac_fix_speed_mx93(void *priv, uint speed, uint
> >>> +mode) {
> >>> +     struct imx_priv_data *dwmac = priv;
> >>> +     int ctrl, old_ctrl, iface;
> >>> +
> >>> +     imx_dwmac_fix_speed(priv, speed, mode);
> >>> +
> >>> +     if (!dwmac || mode != MLO_AN_FIXED)
> >>> +             return;
> >>> +
> >>> +     if (regmap_read(dwmac->intf_regmap, dwmac->intf_reg_off, &iface))
> >>> +             return;
> >>> +
> >>> +     iface &= MX93_GPR_ENET_QOS_INTF_MASK;
> >>> +     if (iface != MX93_GPR_ENET_QOS_INTF_SEL_RGMII)
> >>> +             return;
> >>> +
> >>> +     old_ctrl = readl(dwmac->base_addr + MAC_CTRL_REG);
> >>> +     ctrl = old_ctrl & ~CTRL_SPEED_MASK;
> >>> +     regmap_update_bits(dwmac->intf_regmap, dwmac->intf_reg_off,
> >>> +                        MX93_GPR_ENET_QOS_INTF_MODE_MASK, 0);
> >>> +     writel(ctrl, dwmac->base_addr + MAC_CTRL_REG);
> >>> +
> >>> +     /* Ensure the settings for CTRL are applied and avoid CPU/Compiler
> >>> +      * reordering.
> >>> +      */
> >>> +     wmb();
> >>> +
> >>> +     usleep_range(10, 20);
> >>> +     iface |= MX93_GPR_ENET_QOS_CLK_GEN_EN;
> >>> +     regmap_update_bits(dwmac->intf_regmap, dwmac->intf_reg_off,
> >>> +                        MX93_GPR_ENET_QOS_INTF_MODE_MASK, iface);
> >>> +
> >>> +     writel(old_ctrl, dwmac->base_addr + MAC_CTRL_REG); }
> >>> +
> >>>    static int imx_dwmac_mx93_reset(void *priv, void __iomem *ioaddr)
> >>>    {
> >>>        struct plat_stmmacenet_data *plat_dat = priv; @@ -317,8
> >>> +356,11 @@ static int imx_dwmac_probe(struct platform_device *pdev)
> >>>        plat_dat->exit = imx_dwmac_exit;
> >>>        plat_dat->clks_config = imx_dwmac_clks_config;
> >>>        plat_dat->fix_mac_speed = imx_dwmac_fix_speed;
> >>> +     if (of_machine_is_compatible("fsl,imx93"))
> >>> +             plat_dat->fix_mac_speed = imx_dwmac_fix_speed_mx93;
> >>>        plat_dat->bsp_priv = dwmac;
> >>>        dwmac->plat_dat = plat_dat;
> >>> +     dwmac->base_addr = stmmac_res.addr;
> >>>
> >>>        ret = imx_dwmac_clks_config(dwmac, true);
> >>>        if (ret)
> >>
> >> --
> >> Pengutronix e.K.                | Johannes Zink                  |
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> --
> Pengutronix e.K.                | Johannes Zink                  |
> Steuerwalder Str. 21            |
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