diff mbox series

[net,v3,1/3] net: stmmac: Limit the number of MTL queues to hardware capability

Message ID 20250124101359.2926906-2-hayashi.kunihiko@socionext.com (mailing list archive)
State New
Headers show
Series Limit devicetree parameters to hardware capability | expand

Commit Message

Kunihiko Hayashi Jan. 24, 2025, 10:13 a.m. UTC
The number of MTL queues to use is specified by the parameter
"snps,{tx,rx}-queues-to-use" from stmmac_platform layer.

However, the maximum numbers of queues are constrained by upper limits
determined by the capability of each hardware feature. It's appropriate
to limit the values not to exceed the upper limit values and display
a warning message.

This only works if the hardware capability has the upper limit values.

Fixes: d976a525c371 ("net: stmmac: multiple queues dt configuration")
Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

Comments

Russell King (Oracle) Jan. 24, 2025, 11:43 a.m. UTC | #1
On Fri, Jan 24, 2025 at 07:13:57PM +0900, Kunihiko Hayashi wrote:
> The number of MTL queues to use is specified by the parameter
> "snps,{tx,rx}-queues-to-use" from stmmac_platform layer.
> 
> However, the maximum numbers of queues are constrained by upper limits
> determined by the capability of each hardware feature. It's appropriate
> to limit the values not to exceed the upper limit values and display
> a warning message.
> 
> This only works if the hardware capability has the upper limit values.
> 
> Fixes: d976a525c371 ("net: stmmac: multiple queues dt configuration")
> Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
> ---
>  drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
> 
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> index 7bf275f127c9..be1e6fa6d557 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> @@ -7232,6 +7232,21 @@ static int stmmac_hw_init(struct stmmac_priv *priv)
>  	if (priv->dma_cap.tsoen)
>  		dev_info(priv->device, "TSO supported\n");
>  
> +	if (priv->dma_cap.number_rx_queues &&
> +	    priv->dma_cap.number_rx_queues < priv->plat->rx_queues_to_use) {

While this looks "nicer", which of these two do you think reads better
and is easier to understand:

"If priv->dma_cap.number_rx_queues is set, and
 priv->dma_cap.number_rx_queues is less than
 priv->plat->rx_queues_to_use then print a message about
 priv->plat->rx_queues_to_use exceeding priv->dma_cap.number_rx_queues"

"If priv->dma_cap.number_rx_queues is set, and
 priv->plat->rx_queues_to_use is greater than
 priv->dma_cap.number_rx_queues, then print a message about
 priv->plat->rx_queues_to_use exceeding priv->dma_cap.number_rx_queues"

With the former one has to mentally flip the test around in the if
statement to check that it does indeed match the warning that is
printed.
diff mbox series

Patch

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 7bf275f127c9..be1e6fa6d557 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -7232,6 +7232,21 @@  static int stmmac_hw_init(struct stmmac_priv *priv)
 	if (priv->dma_cap.tsoen)
 		dev_info(priv->device, "TSO supported\n");
 
+	if (priv->dma_cap.number_rx_queues &&
+	    priv->dma_cap.number_rx_queues < priv->plat->rx_queues_to_use) {
+		dev_warn(priv->device,
+			 "Number of Rx queues (%u) exceeds dma capability\n",
+			 priv->plat->rx_queues_to_use);
+		priv->plat->rx_queues_to_use = priv->dma_cap.number_rx_queues;
+	}
+	if (priv->dma_cap.number_tx_queues &&
+	    priv->dma_cap.number_tx_queues < priv->plat->tx_queues_to_use) {
+		dev_warn(priv->device,
+			 "Number of Tx queues (%u) exceeds dma capability\n",
+			 priv->plat->tx_queues_to_use);
+		priv->plat->tx_queues_to_use = priv->dma_cap.number_tx_queues;
+	}
+
 	priv->hw->vlan_fail_q_en =
 		(priv->plat->flags & STMMAC_FLAG_VLAN_FAIL_Q_EN);
 	priv->hw->vlan_fail_q = priv->plat->vlan_fail_q;