From: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>

On SoCs that only support the best-effort queue and not the network
control queue, calling alloc_etherdev_mqs() with fixed values for
TX/RX queues is not appropriate. Use the nc_queues flag from the
per-SoC match data to determine whether the network control queue
is available, and fall back to a single TX/RX queue when it is not.
This ensures correct queue allocation across all supported SoCs.

Fixes: a92f4f0662bf ("ravb: Add nc_queue to struct ravb_hw_info")
Cc: stable@vger.kernel.org
Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
---
v1->v2:
- Added Reviewed-by tag from Niklas.
---
 drivers/net/ethernet/renesas/ravb_main.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
index 69d382e8757d..a200e205825a 100644
--- a/drivers/net/ethernet/renesas/ravb_main.c
+++ b/drivers/net/ethernet/renesas/ravb_main.c
@@ -2926,13 +2926,14 @@ static int ravb_probe(struct platform_device *pdev)
 		return dev_err_probe(&pdev->dev, PTR_ERR(rstc),
 				     "failed to get cpg reset\n");
 
+	info = of_device_get_match_data(&pdev->dev);
+
 	ndev = alloc_etherdev_mqs(sizeof(struct ravb_private),
-				  NUM_TX_QUEUE, NUM_RX_QUEUE);
+				  info->nc_queues ? NUM_TX_QUEUE : 1,
+				  info->nc_queues ? NUM_RX_QUEUE : 1);
 	if (!ndev)
 		return -ENOMEM;
 
-	info = of_device_get_match_data(&pdev->dev);
-
 	ndev->features = info->net_features;
 	ndev->hw_features = info->net_hw_features;
 	ndev->vlan_features = info->vlan_features;
-- 
2.43.0

On Fri, 17 Oct 2025 16:18:28 +0100 Prabhakar wrote:
> On SoCs that only support the best-effort queue and not the network
> control queue, calling alloc_etherdev_mqs() with fixed values for
> TX/RX queues is not appropriate. Use the nc_queues flag from the
> per-SoC match data to determine whether the network control queue
> is available, and fall back to a single TX/RX queue when it is not.
> This ensures correct queue allocation across all supported SoCs.

Same comment as on patch 1, what is the _real_ problem?
Allocating a bit too much memory is not an stable-worthy issue.

Hi Jakub,

Thank you for the review.

On Thu, Oct 23, 2025 at 2:13 AM Jakub Kicinski <kuba@kernel.org> wrote:
>
> On Fri, 17 Oct 2025 16:18:28 +0100 Prabhakar wrote:
> > On SoCs that only support the best-effort queue and not the network
> > control queue, calling alloc_etherdev_mqs() with fixed values for
> > TX/RX queues is not appropriate. Use the nc_queues flag from the
> > per-SoC match data to determine whether the network control queue
> > is available, and fall back to a single TX/RX queue when it is not.
> > This ensures correct queue allocation across all supported SoCs.
>
> Same comment as on patch 1, what is the _real_ problem?
> Allocating a bit too much memory is not an stable-worthy issue.

Ok, I will drop the fixes tag and cc to stable and post it for net-next.

Cheers,
Prabhakar