[PATCH net v4 1/3] net: stmmac: Limit the number of MTL queues to hardware capability

Kunihiko Hayashi
2025-01-27T01:38:24Z

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..97c3d1b89529 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->plat->rx_queues_to_use > priv->dma_cap.number_rx_queues) {
+ 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->plat->tx_queues_to_use > priv->dma_cap.number_tx_queues) {
+ 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;
--
2.25.1