Re: [RFC PATCH v2 4/7] net: stmmac: dwmac-meson8b: add support for the Amlogic T7

[Maxime Chevallier <maxime.chevallier@bootlin.com>]

Hi,

On 10/7/26 10:26, Lucas Tanure wrote:
> The glue registers on the T7 are laid out exactly as the G12A ones, RX
> delay field included, so the T7 can reuse the G12A settings.
> 
> What it does not share is how the controller reaches memory. That path
> runs through a pipeline stage with a gate of its own, and no other
> device has any use for that gate. Nothing claims it, so it is switched
> off as unused and a transfer that has started can never finish.
> 
> Without that gate the controller cannot do DMA at all, so it is
> required rather than optional: a clear probe failure beats an
> undiagnosable hang later.
> 
> Assisted-by: LLM
> Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
> Signed-off-by: Lucas Tanure <tanure@linux.com>

Reviewed-by: Maxime Chevallier <maxime.chevallier@bootlin.com>

Maxime

> ---
>  .../ethernet/stmicro/stmmac/dwmac-meson8b.c   | 19 +++++++++++++++++++
>  1 file changed, 19 insertions(+)
> 
> diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-meson8b.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-meson8b.c
> index d73dfd0ac167..dd10d719ab84 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/dwmac-meson8b.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-meson8b.c
> @@ -81,6 +81,7 @@ struct meson8b_dwmac;
>  struct meson8b_dwmac_data {
>  	int (*set_phy_mode)(struct meson8b_dwmac *dwmac);
>  	bool has_prg_eth1_rgmii_rx_delay;
> +	bool has_pipeline_clk;
>  };
>  
>  struct meson8b_dwmac {
> @@ -402,6 +403,7 @@ static int meson8b_dwmac_probe(struct platform_device *pdev)
>  	struct plat_stmmacenet_data *plat_dat;
>  	struct stmmac_resources stmmac_res;
>  	struct meson8b_dwmac *dwmac;
> +	struct clk *pipeline_clk;
>  	u32 tx_delay_ps;
>  	int ret;
>  
> @@ -485,6 +487,13 @@ static int meson8b_dwmac_probe(struct platform_device *pdev)
>  	if (IS_ERR(dwmac->timing_adj_clk))
>  		return PTR_ERR(dwmac->timing_adj_clk);
>  
> +	if (dwmac->data->has_pipeline_clk) {
> +		pipeline_clk = devm_clk_get_enabled(dwmac->dev, "pipeline");
> +		if (IS_ERR(pipeline_clk))
> +			return dev_err_probe(dwmac->dev, PTR_ERR(pipeline_clk),
> +					     "missing pipeline clock\n");
> +	}
> +
>  	ret = meson8b_init_rgmii_delays(dwmac);
>  	if (ret)
>  		return ret;
> @@ -521,6 +530,12 @@ static const struct meson8b_dwmac_data meson_g12a_dwmac_data = {
>  	.has_prg_eth1_rgmii_rx_delay = true,
>  };
>  
> +static const struct meson8b_dwmac_data meson_t7_dwmac_data = {
> +	.set_phy_mode = meson_axg_set_phy_mode,
> +	.has_prg_eth1_rgmii_rx_delay = true,
> +	.has_pipeline_clk = true,
> +};
> +
>  static const struct of_device_id meson8b_dwmac_match[] = {
>  	{
>  		.compatible = "amlogic,meson8b-dwmac",
> @@ -542,6 +557,10 @@ static const struct of_device_id meson8b_dwmac_match[] = {
>  		.compatible = "amlogic,meson-g12a-dwmac",
>  		.data = &meson_g12a_dwmac_data,
>  	},
> +	{
> +		.compatible = "amlogic,t7-dwmac",
> +		.data = &meson_t7_dwmac_data,
> +	},
>  	{ }
>  };
>  MODULE_DEVICE_TABLE(of, meson8b_dwmac_match);

text:
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Subject: Re: [RFC PATCH v2 4/7] net: stmmac: dwmac-meson8b: add support for
 the Amlogic T7
To: Lucas Tanure <tanure@linux.com>, xianwei.zhao@amlogic.com,
 Andrew Lunn <andrew+netdev@lunn.ch>, "David S. Miller"
 <davem@davemloft.net>, Eric Dumazet <edumazet@kernel.org>,
 Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
 Rob Herring <robh@kernel.org>, Krzysztof Kozlowski <krzk+dt@kernel.org>,
 Conor Dooley <conor+dt@kernel.org>,
 Neil Armstrong <neil.armstrong@linaro.org>,
 Kevin Hilman <khilman@baylibre.com>, Jerome Brunet <jbrunet@baylibre.com>,
 Martin Blumenstingl <martin.blumenstingl@googlemail.com>,
 Maxime Coquelin <mcoquelin.stm32@gmail.com>,
 Alexandre Torgue <alexandre.torgue@foss.st.com>
Cc: netdev@vger.kernel.org, devicetree@vger.kernel.org,
 linux-arm-kernel@lists.infradead.org, linux-amlogic@lists.infradead.org,
 linux-kernel@vger.kernel.org
References: <20261007082627.63807-1-tanure@linux.com>
 <20261007082627.63807-5-tanure@linux.com>
Content-Language: en-US
From: Maxime Chevallier <maxime.chevallier@bootlin.com>
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X-Rspamd-Queue-Id: 622F411D500EF

Hi,

On 10/7/26 10:26, Lucas Tanure wrote:
> The glue registers on the T7 are laid out exactly as the G12A ones, RX
> delay field included, so the T7 can reuse the G12A settings.
> 
> What it does not share is how the controller reaches memory. That path
> runs through a pipeline stage with a gate of its own, and no other
> device has any use for that gate. Nothing claims it, so it is switched
> off as unused and a transfer that has started can never finish.
> 
> Without that gate the controller cannot do DMA at all, so it is
> required rather than optional: a clear probe failure beats an
> undiagnosable hang later.
> 
> Assisted-by: LLM
> Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
> Signed-off-by: Lucas Tanure <tanure@linux.com>

Reviewed-by: Maxime Chevallier <maxime.chevallier@bootlin.com>

Maxime

> ---
>  .../ethernet/stmicro/stmmac/dwmac-meson8b.c   | 19 +++++++++++++++++++
>  1 file changed, 19 insertions(+)
> 
> diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-meson8b.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-meson8b.c
> index d73dfd0ac167..dd10d719ab84 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/dwmac-meson8b.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-meson8b.c
> @@ -81,6 +81,7 @@ struct meson8b_dwmac;
>  struct meson8b_dwmac_data {
>  	int (*set_phy_mode)(struct meson8b_dwmac *dwmac);
>  	bool has_prg_eth1_rgmii_rx_delay;
> +	bool has_pipeline_clk;
>  };
>  
>  struct meson8b_dwmac {
> @@ -402,6 +403,7 @@ static int meson8b_dwmac_probe(struct platform_device *pdev)
>  	struct plat_stmmacenet_data *plat_dat;
>  	struct stmmac_resources stmmac_res;
>  	struct meson8b_dwmac *dwmac;
> +	struct clk *pipeline_clk;
>  	u32 tx_delay_ps;
>  	int ret;
>  
> @@ -485,6 +487,13 @@ static int meson8b_dwmac_probe(struct platform_device *pdev)
>  	if (IS_ERR(dwmac->timing_adj_clk))
>  		return PTR_ERR(dwmac->timing_adj_clk);
>  
> +	if (dwmac->data->has_pipeline_clk) {
> +		pipeline_clk = devm_clk_get_enabled(dwmac->dev, "pipeline");
> +		if (IS_ERR(pipeline_clk))
> +			return dev_err_probe(dwmac->dev, PTR_ERR(pipeline_clk),
> +					     "missing pipeline clock\n");
> +	}
> +
>  	ret = meson8b_init_rgmii_delays(dwmac);
>  	if (ret)
>  		return ret;
> @@ -521,6 +530,12 @@ static const struct meson8b_dwmac_data meson_g12a_dwmac_data = {
>  	.has_prg_eth1_rgmii_rx_delay = true,
>  };
>  
> +static const struct meson8b_dwmac_data meson_t7_dwmac_data = {
> +	.set_phy_mode = meson_axg_set_phy_mode,
> +	.has_prg_eth1_rgmii_rx_delay = true,
> +	.has_pipeline_clk = true,
> +};
> +
>  static const struct of_device_id meson8b_dwmac_match[] = {
>  	{
>  		.compatible = "amlogic,meson8b-dwmac",
> @@ -542,6 +557,10 @@ static const struct of_device_id meson8b_dwmac_match[] = {
>  		.compatible = "amlogic,meson-g12a-dwmac",
>  		.data = &meson_g12a_dwmac_data,
>  	},
> +	{
> +		.compatible = "amlogic,t7-dwmac",
> +		.data = &meson_t7_dwmac_data,
> +	},
>  	{ }
>  };
>  MODULE_DEVICE_TABLE(of, meson8b_dwmac_match);



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