[PATCH net-next 0/3] net: stmmac: fpe: pmac and fprq fixes

[PATCH net-next 0/3] net: stmmac: fpe: pmac and fprq fixes

[muhammad.nazim.amirul.nazle.asmade]

From: Nazim Amirul <muhammad.nazim.amirul.nazle.asmade@altera.com>

Three fixes for the stmmac FPE implementation:

- Keep pmac_enabled true in DWMAC since the preemptive MAC is always
  on, enforce this in set_mm(), and guard set_mm() with fpesel check
- Fix missing return in stmmac_fpe_init() when FPE is unsupported
- Move fprq configuration to stmmac_fpe_configure_pmac() where it
  belongs, using u32_replace_bits() to simplify the update

Nazim Amirul (3):
  net: stmmac: fpe: Enforce pmac_enabled in set_mm and keep it on at
    init
  net: stmmac: fpe: Add missing return in stmmac_fpe_init()
  net: stmmac: fpe: Move fprq configuration to
    stmmac_fpe_configure_pmac()

 .../ethernet/stmicro/stmmac/stmmac_ethtool.c  |  7 +++++
 .../net/ethernet/stmicro/stmmac/stmmac_fpe.c  | 30 ++++++++++++-------
 2 files changed, 26 insertions(+), 11 deletions(-)

-- 
2.43.7

[PATCH net-next 1/3] net: stmmac: fpe: Enforce pmac_enabled in set_mm and keep it on at init

[muhammad.nazim.amirul.nazle.asmade]

From: Nazim Amirul <muhammad.nazim.amirul.nazle.asmade@altera.com>

The preemptive MAC in DWMAC is always enabled, meaning DWMAC is always
ready to receive preemptive mPackets. Initialize pmac_enabled to true
at init time and reject attempts to disable it via ethtool set_mm.

Also add a missing fpesel capability check in stmmac_set_mm() to return
-EOPNOTSUPP early on hardware without FPE support.

Signed-off-by: Rohan G Thomas <rohan.g.thomas@altera.com>
Signed-off-by: Nazim Amirul <muhammad.nazim.amirul.nazle.asmade@altera.com>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c | 7 +++++++
 drivers/net/ethernet/stmicro/stmmac/stmmac_fpe.c     | 5 +++++
 2 files changed, 12 insertions(+)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c
index 92585d27ab88..8ebdd249e5c8 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c
@@ -1064,6 +1064,13 @@ static int stmmac_set_mm(struct net_device *ndev, struct ethtool_mm_cfg *cfg,
 	if (err)
 		return err;
 
+	if (!priv->dma_cap.fpesel)
+		return -EOPNOTSUPP;
+
+	/* DWMAC always have preemptible MAC enabled */
+	if (!cfg->pmac_enabled)
+		return -EINVAL;
+
 	stmmac_fpe_set_add_frag_size(priv, frag_size);
 	ethtool_mmsv_set_mm(&priv->fpe_cfg.mmsv, cfg);
 
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_fpe.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_fpe.c
index c54c70224351..2f880c5e35b0 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_fpe.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_fpe.c
@@ -176,6 +176,11 @@ void stmmac_fpe_init(struct stmmac_priv *priv)
 	if ((!priv->fpe_cfg.reg || !priv->hw->mac->fpe_map_preemption_class) &&
 	    priv->dma_cap.fpesel)
 		dev_info(priv->device, "FPE is not supported by driver.\n");
+
+	/* The preemptive MAC in DWMAC is always enabled, so initialize
+	 * pmac_enabled to true to reflect the hardware state.
+	 */
+	priv->fpe_cfg.mmsv.pmac_enabled = true;
 }
 
 int stmmac_fpe_get_add_frag_size(struct stmmac_priv *priv)
-- 
2.43.7

Re: [PATCH net-next 1/3] net: stmmac: fpe: Enforce pmac_enabled in set_mm and keep it on at init

[Maxime Chevallier]

Hi,

On 7/29/26 03:52, muhammad.nazim.amirul.nazle.asmade@altera.com wrote:
> From: Nazim Amirul <muhammad.nazim.amirul.nazle.asmade@altera.com>
> 
> The preemptive MAC in DWMAC is always enabled, meaning DWMAC is always
> ready to receive preemptive mPackets. Initialize pmac_enabled to true
> at init time and reject attempts to disable it via ethtool set_mm.
> 
> Also add a missing fpesel capability check in stmmac_set_mm() to return
> -EOPNOTSUPP early on hardware without FPE support.
> 
> Signed-off-by: Rohan G Thomas <rohan.g.thomas@altera.com>
> Signed-off-by: Nazim Amirul <muhammad.nazim.amirul.nazle.asmade@altera.com>

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

Maxime

> ---
>  drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c | 7 +++++++
>  drivers/net/ethernet/stmicro/stmmac/stmmac_fpe.c     | 5 +++++
>  2 files changed, 12 insertions(+)
> 
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c
> index 92585d27ab88..8ebdd249e5c8 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c
> @@ -1064,6 +1064,13 @@ static int stmmac_set_mm(struct net_device *ndev, struct ethtool_mm_cfg *cfg,
>  	if (err)
>  		return err;
>  
> +	if (!priv->dma_cap.fpesel)
> +		return -EOPNOTSUPP;
> +
> +	/* DWMAC always have preemptible MAC enabled */
> +	if (!cfg->pmac_enabled)
> +		return -EINVAL;
> +
>  	stmmac_fpe_set_add_frag_size(priv, frag_size);
>  	ethtool_mmsv_set_mm(&priv->fpe_cfg.mmsv, cfg);
>  
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_fpe.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_fpe.c
> index c54c70224351..2f880c5e35b0 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_fpe.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_fpe.c
> @@ -176,6 +176,11 @@ void stmmac_fpe_init(struct stmmac_priv *priv)
>  	if ((!priv->fpe_cfg.reg || !priv->hw->mac->fpe_map_preemption_class) &&
>  	    priv->dma_cap.fpesel)
>  		dev_info(priv->device, "FPE is not supported by driver.\n");
> +
> +	/* The preemptive MAC in DWMAC is always enabled, so initialize
> +	 * pmac_enabled to true to reflect the hardware state.
> +	 */
> +	priv->fpe_cfg.mmsv.pmac_enabled = true;
>  }
>  
>  int stmmac_fpe_get_add_frag_size(struct stmmac_priv *priv)

[PATCH net-next 2/3] net: stmmac: fpe: Add missing return in stmmac_fpe_init()

[muhammad.nazim.amirul.nazle.asmade]

From: Nazim Amirul <muhammad.nazim.amirul.nazle.asmade@altera.com>

When FPE is not supported by the driver, stmmac_fpe_init() prints a
warning but falls through into the pmac_enabled initialization, which
should only be reached on supported hardware. Add the missing return
to prevent this.

Signed-off-by: Rohan G Thomas <rohan.g.thomas@altera.com>
Signed-off-by: Nazim Amirul <muhammad.nazim.amirul.nazle.asmade@altera.com>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_fpe.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_fpe.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_fpe.c
index 2f880c5e35b0..3436e962a238 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_fpe.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_fpe.c
@@ -174,8 +174,10 @@ void stmmac_fpe_init(struct stmmac_priv *priv)
 			  &stmmac_mmsv_ops);
 
 	if ((!priv->fpe_cfg.reg || !priv->hw->mac->fpe_map_preemption_class) &&
-	    priv->dma_cap.fpesel)
+	    priv->dma_cap.fpesel) {
 		dev_info(priv->device, "FPE is not supported by driver.\n");
+		return;
+	}
 
 	/* The preemptive MAC in DWMAC is always enabled, so initialize
 	 * pmac_enabled to true to reflect the hardware state.
-- 
2.43.7

Re: [PATCH net-next 2/3] net: stmmac: fpe: Add missing return in stmmac_fpe_init()

[Maxime Chevallier]

Hi,

On 7/29/26 03:52, muhammad.nazim.amirul.nazle.asmade@altera.com wrote:
> From: Nazim Amirul <muhammad.nazim.amirul.nazle.asmade@altera.com>
> 
> When FPE is not supported by the driver, stmmac_fpe_init() prints a
> warning but falls through into the pmac_enabled initialization, which
> should only be reached on supported hardware. Add the missing return
> to prevent this.
> 
> Signed-off-by: Rohan G Thomas <rohan.g.thomas@altera.com>
> Signed-off-by: Nazim Amirul <muhammad.nazim.amirul.nazle.asmade@altera.com>

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

Thanks,

Maxime

> ---
>  drivers/net/ethernet/stmicro/stmmac/stmmac_fpe.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_fpe.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_fpe.c
> index 2f880c5e35b0..3436e962a238 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_fpe.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_fpe.c
> @@ -174,8 +174,10 @@ void stmmac_fpe_init(struct stmmac_priv *priv)
>  			  &stmmac_mmsv_ops);
>  
>  	if ((!priv->fpe_cfg.reg || !priv->hw->mac->fpe_map_preemption_class) &&
> -	    priv->dma_cap.fpesel)
> +	    priv->dma_cap.fpesel) {
>  		dev_info(priv->device, "FPE is not supported by driver.\n");
> +		return;
> +	}
>  
>  	/* The preemptive MAC in DWMAC is always enabled, so initialize
>  	 * pmac_enabled to true to reflect the hardware state.

[PATCH net-next 3/3] net: stmmac: fpe: Move fprq configuration to stmmac_fpe_configure_pmac()

[muhammad.nazim.amirul.nazle.asmade]

From: Nazim Amirul <muhammad.nazim.amirul.nazle.asmade@altera.com>

The Frame Preemption Residue Queue (fprq) controls which Rx queue
receives residual preemptive mPackets from the pmac. This is a pmac
concern, not a TX concern, so move its configuration from
stmmac_fpe_configure_tx() to stmmac_fpe_configure_pmac() where it
logically belongs.

Use u32_replace_bits() instead of the open-coded mask/shift sequence.

Signed-off-by: Rohan G Thomas <rohan.g.thomas@altera.com>
Signed-off-by: Nazim Amirul <muhammad.nazim.amirul.nazle.asmade@altera.com>
---
 .../net/ethernet/stmicro/stmmac/stmmac_fpe.c  | 20 +++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_fpe.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_fpe.c
index 3436e962a238..27e500edc8ac 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_fpe.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_fpe.c
@@ -47,20 +47,13 @@ static void stmmac_fpe_configure_tx(struct ethtool_mmsv *mmsv, bool tx_enable)
 	struct stmmac_fpe_cfg *cfg = container_of(mmsv, struct stmmac_fpe_cfg, mmsv);
 	struct stmmac_priv *priv = container_of(cfg, struct stmmac_priv, fpe_cfg);
 	const struct stmmac_fpe_reg *reg = cfg->reg;
-	u32 num_rxq = priv->plat->rx_queues_to_use;
 	void __iomem *ioaddr = priv->ioaddr;
-	u32 value;
 
-	if (tx_enable) {
+	if (tx_enable)
 		cfg->fpe_csr = STMMAC_MAC_FPE_CTRL_STS_EFPE;
-		value = readl(ioaddr + reg->rxq_ctrl1_reg);
-		value &= ~reg->fprq_mask;
-		/* Keep this SHIFT, FIELD_PREP() expects a constant mask :-/ */
-		value |= (num_rxq - 1) << __ffs(reg->fprq_mask);
-		writel(value, ioaddr + reg->rxq_ctrl1_reg);
-	} else {
+	else
 		cfg->fpe_csr = 0;
-	}
+
 	writel(cfg->fpe_csr, ioaddr + reg->mac_fpe_reg);
 }
 
@@ -68,6 +61,7 @@ static void stmmac_fpe_configure_pmac(struct ethtool_mmsv *mmsv, bool pmac_enabl
 {
 	struct stmmac_fpe_cfg *cfg = container_of(mmsv, struct stmmac_fpe_cfg, mmsv);
 	struct stmmac_priv *priv = container_of(cfg, struct stmmac_priv, fpe_cfg);
+	u32 num_rxq = priv->plat->rx_queues_to_use;
 	const struct stmmac_fpe_reg *reg = cfg->reg;
 	void __iomem *ioaddr = priv->ioaddr;
 	unsigned long flags;
@@ -83,6 +77,12 @@ static void stmmac_fpe_configure_pmac(struct ethtool_mmsv *mmsv, bool pmac_enabl
 
 			value |= reg->int_en_bit;
 		}
+		/* Frame Preemption Residue Queue is the Rx Queue to which
+		 * residual preemptive mPackets must be forwarded from the pmac.
+		 */
+		writel(u32_replace_bits(readl(ioaddr + reg->rxq_ctrl1_reg),
+					num_rxq - 1, reg->fprq_mask),
+		       ioaddr + reg->rxq_ctrl1_reg);
 	} else {
 		value &= ~reg->int_en_bit;
 	}
-- 
2.43.7

Re: [PATCH net-next 3/3] net: stmmac: fpe: Move fprq configuration to stmmac_fpe_configure_pmac()

[Maxime Chevallier]

Hi,

On 7/29/26 03:52, muhammad.nazim.amirul.nazle.asmade@altera.com wrote:
> From: Nazim Amirul <muhammad.nazim.amirul.nazle.asmade@altera.com>
> 
> The Frame Preemption Residue Queue (fprq) controls which Rx queue
> receives residual preemptive mPackets from the pmac. This is a pmac
> concern, not a TX concern, so move its configuration from
> stmmac_fpe_configure_tx() to stmmac_fpe_configure_pmac() where it
> logically belongs.
> 
> Use u32_replace_bits() instead of the open-coded mask/shift sequence.
> 
> Signed-off-by: Rohan G Thomas <rohan.g.thomas@altera.com>
> Signed-off-by: Nazim Amirul <muhammad.nazim.amirul.nazle.asmade@altera.com>
> ---
>  .../net/ethernet/stmicro/stmmac/stmmac_fpe.c  | 20 +++++++++----------
>  1 file changed, 10 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_fpe.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_fpe.c
> index 3436e962a238..27e500edc8ac 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_fpe.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_fpe.c
> @@ -47,20 +47,13 @@ static void stmmac_fpe_configure_tx(struct ethtool_mmsv *mmsv, bool tx_enable)
>  	struct stmmac_fpe_cfg *cfg = container_of(mmsv, struct stmmac_fpe_cfg, mmsv);
>  	struct stmmac_priv *priv = container_of(cfg, struct stmmac_priv, fpe_cfg);
>  	const struct stmmac_fpe_reg *reg = cfg->reg;
> -	u32 num_rxq = priv->plat->rx_queues_to_use;
>  	void __iomem *ioaddr = priv->ioaddr;
> -	u32 value;
>  
> -	if (tx_enable) {
> +	if (tx_enable)
>  		cfg->fpe_csr = STMMAC_MAC_FPE_CTRL_STS_EFPE;
> -		value = readl(ioaddr + reg->rxq_ctrl1_reg);
> -		value &= ~reg->fprq_mask;
> -		/* Keep this SHIFT, FIELD_PREP() expects a constant mask :-/ */
> -		value |= (num_rxq - 1) << __ffs(reg->fprq_mask);
> -		writel(value, ioaddr + reg->rxq_ctrl1_reg);
> -	} else {
> +	else
>  		cfg->fpe_csr = 0;
> -	}
> +
>  	writel(cfg->fpe_csr, ioaddr + reg->mac_fpe_reg);
>  }
>  
> @@ -68,6 +61,7 @@ static void stmmac_fpe_configure_pmac(struct ethtool_mmsv *mmsv, bool pmac_enabl
>  {
>  	struct stmmac_fpe_cfg *cfg = container_of(mmsv, struct stmmac_fpe_cfg, mmsv);
>  	struct stmmac_priv *priv = container_of(cfg, struct stmmac_priv, fpe_cfg);
> +	u32 num_rxq = priv->plat->rx_queues_to_use;
>  	const struct stmmac_fpe_reg *reg = cfg->reg;
>  	void __iomem *ioaddr = priv->ioaddr;
>  	unsigned long flags;
> @@ -83,6 +77,12 @@ static void stmmac_fpe_configure_pmac(struct ethtool_mmsv *mmsv, bool pmac_enabl
>  
>  			value |= reg->int_en_bit;
>  		}
> +		/* Frame Preemption Residue Queue is the Rx Queue to which
> +		 * residual preemptive mPackets must be forwarded from the pmac.
> +		 */
> +		writel(u32_replace_bits(readl(ioaddr + reg->rxq_ctrl1_reg),
> +					num_rxq - 1, reg->fprq_mask),
> +		       ioaddr + reg->rxq_ctrl1_reg);
>  	} else {
>  		value &= ~reg->int_en_bit;
>  	}

Not a bit fan of the writel(u32_replace(readl(...))) but I don't feel strong
enough about that to warrant a resend 

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

Maxime