Re: [PATCH v1 1/1] net: macb: Shorten max_tx_len to 4KiB - 56 on mpfs

[<Nicolas.Ferre@microchip.com>]

On 13/04/2023 at 20:03, daire.mcnamara@microchip.com wrote:
> From: Daire McNamara <daire.mcnamara@microchip.com>
> 
> On mpfs, with SRAM configured for 4 queues, setting max_tx_len
> to GEM_TX_MAX_LEN=0x3f0 results multiple AMBA errors.
> Setting max_tx_len to (4KiB - 56) removes those errors.
> 
> The details are described in erratum 1686 by Cadence
> 
> The max jumbo frame size is also reduced for mpfs to (4KiB - 56).
> 
> Signed-off-by: Daire McNamara <daire.mcnamara@microchip.com>

Looks good to me:
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>

Best regards,
   Nicolas

> ---
>   drivers/net/ethernet/cadence/macb.h      |  1 +
>   drivers/net/ethernet/cadence/macb_main.c | 16 ++++++++++++----
>   2 files changed, 13 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/net/ethernet/cadence/macb.h b/drivers/net/ethernet/cadence/macb.h
> index 14dfec4db8f9..989e7c5db9b9 100644
> --- a/drivers/net/ethernet/cadence/macb.h
> +++ b/drivers/net/ethernet/cadence/macb.h
> @@ -1175,6 +1175,7 @@ struct macb_config {
>   			    struct clk **hclk, struct clk **tx_clk,
>   			    struct clk **rx_clk, struct clk **tsu_clk);
>   	int	(*init)(struct platform_device *pdev);
> +	unsigned int		max_tx_length;
>   	int	jumbo_max_len;
>   	const struct macb_usrio_config *usrio;
>   };
> diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
> index 66e30561569e..1f362bbc360f 100644
> --- a/drivers/net/ethernet/cadence/macb_main.c
> +++ b/drivers/net/ethernet/cadence/macb_main.c
> @@ -4095,14 +4095,12 @@ static int macb_init(struct platform_device *pdev)
>   
>   	/* setup appropriated routines according to adapter type */
>   	if (macb_is_gem(bp)) {
> -		bp->max_tx_length = GEM_MAX_TX_LEN;
>   		bp->macbgem_ops.mog_alloc_rx_buffers = gem_alloc_rx_buffers;
>   		bp->macbgem_ops.mog_free_rx_buffers = gem_free_rx_buffers;
>   		bp->macbgem_ops.mog_init_rings = gem_init_rings;
>   		bp->macbgem_ops.mog_rx = gem_rx;
>   		dev->ethtool_ops = &gem_ethtool_ops;
>   	} else {
> -		bp->max_tx_length = MACB_MAX_TX_LEN;
>   		bp->macbgem_ops.mog_alloc_rx_buffers = macb_alloc_rx_buffers;
>   		bp->macbgem_ops.mog_free_rx_buffers = macb_free_rx_buffers;
>   		bp->macbgem_ops.mog_init_rings = macb_init_rings;
> @@ -4839,7 +4837,8 @@ static const struct macb_config mpfs_config = {
>   	.clk_init = macb_clk_init,
>   	.init = init_reset_optional,
>   	.usrio = &macb_default_usrio,
> -	.jumbo_max_len = 10240,
> +	.max_tx_length = 4040, /* Cadence Erratum 1686 */
> +	.jumbo_max_len = 4040,
>   };
>   
>   static const struct macb_config sama7g5_gem_config = {
> @@ -4986,8 +4985,17 @@ static int macb_probe(struct platform_device *pdev)
>   	bp->tx_clk = tx_clk;
>   	bp->rx_clk = rx_clk;
>   	bp->tsu_clk = tsu_clk;
> -	if (macb_config)
> +	if (macb_config) {
> +		if (macb_is_gem(bp)) {
> +			if (macb_config->max_tx_length)
> +				bp->max_tx_length = macb_config->max_tx_length;
> +			else
> +				bp->max_tx_length = GEM_MAX_TX_LEN;
> +		} else {
> +			bp->max_tx_length = MACB_MAX_TX_LEN;
> +		}
>   		bp->jumbo_max_len = macb_config->jumbo_max_len;
> +	}
>   
>   	bp->wol = 0;
>   	if (of_property_read_bool(np, "magic-packet"))

-- 
Nicolas Ferre