Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <e32c89e1-7385-105b-63c9-74f58c2253cb@pengutronix.de>
Date:   Wed, 2 Aug 2023 08:25:46 +0200
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101
 Thunderbird/102.13.1
Subject: Re: [EXT] Re: [PATCH v3 net 2/2] net: stmmac: dwmac-imx: pause the
 TXC clock in fixed-link
To:     Shenwei Wang <shenwei.wang@nxp.com>,
        Russell King <linux@armlinux.org.uk>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Maxime Coquelin <mcoquelin.stm32@gmail.com>,
        Shawn Guo <shawnguo@kernel.org>,
        Sascha Hauer <s.hauer@pengutronix.de>,
        Neil Armstrong <neil.armstrong@linaro.org>,
        Kevin Hilman <khilman@baylibre.com>,
        Vinod Koul <vkoul@kernel.org>, Chen-Yu Tsai <wens@csie.org>,
        Jernej Skrabec <jernej.skrabec@gmail.com>,
        Samuel Holland <samuel@sholland.org>
Cc:     Giuseppe Cavallaro <peppe.cavallaro@st.com>,
        Alexandre Torgue <alexandre.torgue@foss.st.com>,
        Jose Abreu <joabreu@synopsys.com>,
        Pengutronix Kernel Team <kernel@pengutronix.de>,
        Fabio Estevam <festevam@gmail.com>,
        dl-linux-imx <linux-imx@nxp.com>,
        Jerome Brunet <jbrunet@baylibre.com>,
        Martin Blumenstingl <martin.blumenstingl@googlemail.com>,
        Bhupesh Sharma <bhupesh.sharma@linaro.org>,
        Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>,
        Simon Horman <simon.horman@corigine.com>,
        Andrew Halaney <ahalaney@redhat.com>,
        Bartosz Golaszewski <bartosz.golaszewski@linaro.org>,
        Wong Vee Khee <veekhee@apple.com>,
        Revanth Kumar Uppala <ruppala@nvidia.com>,
        Jochen Henneberg <jh@henneberg-systemdesign.com>,
        "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
        "linux-stm32@st-md-mailman.stormreply.com" 
        <linux-stm32@st-md-mailman.stormreply.com>,
        "linux-arm-kernel@lists.infradead.org" 
        <linux-arm-kernel@lists.infradead.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-amlogic@lists.infradead.org" 
        <linux-amlogic@lists.infradead.org>,
        "imx@lists.linux.dev" <imx@lists.linux.dev>,
        Frank Li <frank.li@nxp.com>
References: <20230731161929.2341584-1-shenwei.wang@nxp.com>
 <20230731161929.2341584-3-shenwei.wang@nxp.com>
 <bf2979c4-0b63-be53-b530-3d7385796534@pengutronix.de>
 <PAXPR04MB9185D7D3B088E4786A216044890AA@PAXPR04MB9185.eurprd04.prod.outlook.com>
Content-Language: en-US, de-DE
From:   Johannes Zink <j.zink@pengutronix.de>
In-Reply-To: <PAXPR04MB9185D7D3B088E4786A216044890AA@PAXPR04MB9185.eurprd04.prod.outlook.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Precedence: bulk

Hi Shenwei,

On 8/1/23 19:10, Shenwei Wang wrote:
> 
> 
>> -----Original Message-----
>> From: Johannes Zink <j.zink@pengutronix.de>
>> Sent: Tuesday, August 1, 2023 7:48 AM
>> To: Shenwei Wang <shenwei.wang@nxp.com>; Russell King
>> <linux@armlinux.org.uk>; David S. Miller <davem@davemloft.net>; Eric
>> Dumazet <edumazet@google.com>; Jakub Kicinski <kuba@kernel.org>; Paolo
>> Abeni <pabeni@redhat.com>; Maxime Coquelin
>> <mcoquelin.stm32@gmail.com>; Shawn Guo <shawnguo@kernel.org>; Sascha
>> Hauer <s.hauer@pengutronix.de>; Neil Armstrong <neil.armstrong@linaro.org>;
>> Kevin Hilman <khilman@baylibre.com>; Vinod Koul <vkoul@kernel.org>; Chen-
>> Yu Tsai <wens@csie.org>; Jernej Skrabec <jernej.skrabec@gmail.com>; Samuel
>> Holland <samuel@sholland.org>
>> Cc: Giuseppe Cavallaro <peppe.cavallaro@st.com>; Alexandre Torgue
>> <alexandre.torgue@foss.st.com>; Jose Abreu <joabreu@synopsys.com>;
>> Pengutronix Kernel Team <kernel@pengutronix.de>; Fabio Estevam
>> <festevam@gmail.com>; dl-linux-imx <linux-imx@nxp.com>; Jerome Brunet
>> <jbrunet@baylibre.com>; Martin Blumenstingl
>> <martin.blumenstingl@googlemail.com>; Bhupesh Sharma
>> <bhupesh.sharma@linaro.org>; Nobuhiro Iwamatsu
>> <nobuhiro1.iwamatsu@toshiba.co.jp>; Simon Horman
>> <simon.horman@corigine.com>; Andrew Halaney <ahalaney@redhat.com>;
>> Bartosz Golaszewski <bartosz.golaszewski@linaro.org>; Wong Vee Khee
>> <veekhee@apple.com>; Revanth Kumar Uppala <ruppala@nvidia.com>; Jochen
>> Henneberg <jh@henneberg-systemdesign.com>; netdev@vger.kernel.org; linux-
>> stm32@st-md-mailman.stormreply.com; linux-arm-kernel@lists.infradead.org;
>> linux-kernel@vger.kernel.org; linux-amlogic@lists.infradead.org;
>> imx@lists.linux.dev; Frank Li <frank.li@nxp.com>
>> 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.

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

Thanks
Johannes

[1] ZMk/xqRP67zXHNrf@shell.armlinux.org.uk


> 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@nxp.com>
>>> Reviewed-by: Frank Li <frank.li@nxp.com>
>>> ---
>>>    .../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                  |
>> Steuerwalder Str. 21            |
>> https://www.pe/
>> ngutronix.de%2F&data=05%7C01%7Cshenwei.wang%40nxp.com%7C761fbb75c
>> 1c24cfe091508db928d8ade%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C
>> 0%7C638264908852977732%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjA
>> wMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%
>> 7C&sdata=2l2zNfIaNnRJENmERehNae8g%2F%2BQqlxD2YRx7ksY2X%2BE%3D&r
>> eserved=0    |
>> 31137 Hildesheim, Germany       | Phone: +49-5121-206917-0       |
>> Amtsgericht Hildesheim, HRA 2686| Fax:   +49-5121-206917-5555    |
> 
> 

-- 
Pengutronix e.K.                | Johannes Zink                  |
Steuerwalder Str. 21            | https://www.pengutronix.de/    |
31137 Hildesheim, Germany       | Phone: +49-5121-206917-0       |
Amtsgericht Hildesheim, HRA 2686| Fax:   +49-5121-206917-5555    |