Re: [PATCH net-next 2/3] net/stmmac/dwxgmac: Extend MTL/DMA support to 16 queues

[Andrew Lunn <andrew@lunn.ch>]

On Mon, May 11, 2026 at 06:54:15PM +0200, Jakub Raczynski wrote:
> New datasheets for XGMAC (3.20a and 3.40a, depending on product) support up to
> 16 MTL/DMA queues. Before we increase max amount through macro,
> prepare dwxgmac functions to handle that.
> 
> Signed-off-by: Jakub Raczynski <j.raczynski@samsung.com>
> ---
>  .../net/ethernet/stmicro/stmmac/dwxgmac2.h    |  2 ++
>  .../ethernet/stmicro/stmmac/dwxgmac2_core.c   | 24 +++++++++++++++++--
>  2 files changed, 24 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ethernet/stmicro/stmmac/dwxgmac2.h b/drivers/net/ethernet/stmicro/stmmac/dwxgmac2.h
> index 51943705a2b0..bd333afe7e1b 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/dwxgmac2.h
> +++ b/drivers/net/ethernet/stmicro/stmmac/dwxgmac2.h
> @@ -257,6 +257,8 @@
>  #define XGMAC_MTL_INT_STATUS		0x00001020
>  #define XGMAC_MTL_RXQ_DMA_MAP0		0x00001030
>  #define XGMAC_MTL_RXQ_DMA_MAP1		0x00001034
> +#define XGMAC_MTL_RXQ_DMA_MAP2		0x00001038
> +#define XGMAC_MTL_RXQ_DMA_MAP3		0x0000103c
>  #define XGMAC_QxMDMACH(x)		GENMASK((x) * 8 + 7, (x) * 8)
>  #define XGMAC_QxMDMACH_SHIFT(x)		((x) * 8)
>  #define XGMAC_QDDMACH			BIT(7)
> diff --git a/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_core.c b/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_core.c
> index 98b3e0cc84fa..76f8214a6e5b 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_core.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_core.c
> @@ -266,9 +266,29 @@ static void dwxgmac2_map_mtl_to_dma(struct mac_device_info *hw, u32 queue,
>  	void __iomem *ioaddr = hw->pcsr;
>  	u32 value, reg;
>  
> -	reg = (queue < 4) ? XGMAC_MTL_RXQ_DMA_MAP0 : XGMAC_MTL_RXQ_DMA_MAP1;
> -	if (queue >= 4)
> +	switch (queue / 4) {
> +	// queue 0 ~ 3
> +	case 0:
> +		reg = XGMAC_MTL_RXQ_DMA_MAP0;
> +		break;
> +	// queue 4 ~ 7

I think

	switch (queue):
	case 0 ... 3:
	     reg = XGMAC_MTL_RXQ_DMA_MAP0;

is more readable, and expresses in code what you had in the comment.

   Andrew