netdev - Re: [PATCH net 1/2] net: ethernet: mtk_eth_soc: reset all TX queues on DMA free

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Message-ID: <aBZO-nmFoKLx5E5w@lore-desk>
Date: Sat, 3 May 2025 19:14:34 +0200
From: Lorenzo Bianconi <lorenzo@...nel.org>
To: Daniel Golle <daniel@...rotopia.org>
Cc: Felix Fietkau <nbd@....name>, Sean Wang <sean.wang@...iatek.com>,
	Andrew Lunn <andrew+netdev@...n.ch>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Matthias Brugger <matthias.bgg@...il.com>,
	AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
	Elad Yifee <eladwf@...il.com>, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-mediatek@...ts.infradead.org
Subject: Re: [PATCH net 1/2] net: ethernet: mtk_eth_soc: reset all TX queues
 on DMA free

> The purpose of resetting the TX queue is to reset the
> byte and packet count as well as to clear the software
> flow control XOFF bit.
> 
> MediaTek developers pointed out that netdev_reset_queue would only
> resets queue 0 of the network device.
> 
> Queues that are not reset may cause unexpected issues.
> 
> Packets may stop being sent after reset and "transmit timeout" log may
> be displayed.
> 
> Import fix from MediaTek's SDK to resolve this issue.
> 
> Link: https://git01.mediatek.com/plugins/gitiles/openwrt/feeds/mtk-openwrt-feeds/+/319c0d9905579a46dc448579f892f364f1f84818
> Fixes: f63959c7eec31 ("net: ethernet: mtk_eth_soc: implement multi-queue support for per-port queues")
> Signed-off-by: Daniel Golle <daniel@...rotopia.org>
> ---
>  drivers/net/ethernet/mediatek/mtk_eth_soc.c | 16 ++++++++++++----
>  1 file changed, 12 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.c b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
> index 217355d79bbb7..d6d4c2daebab0 100644
> --- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
> +++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
> @@ -3274,11 +3274,19 @@ static int mtk_dma_init(struct mtk_eth *eth)
>  static void mtk_dma_free(struct mtk_eth *eth)
>  {
>  	const struct mtk_soc_data *soc = eth->soc;
> -	int i;
> +	int i, j, txqs = 1;
> +
> +	if (MTK_HAS_CAPS(eth->soc->caps, MTK_QDMA))
> +		txqs = MTK_QDMA_NUM_QUEUES;
> +
> +	for (i = 0; i < MTK_MAX_DEVS; i++) {
> +		if (!eth->netdev[i])
> +			continue;
> +
> +		for (j = 0; j < txqs; j++)
> +			netdev_tx_reset_queue(netdev_get_tx_queue(eth->netdev[i], j));

nit: you can use netdev_tx_reset_subqueue() here.

Regards,
Lorenzo

> +	}
>  
> -	for (i = 0; i < MTK_MAX_DEVS; i++)
> -		if (eth->netdev[i])
> -			netdev_reset_queue(eth->netdev[i]);
>  	if (!MTK_HAS_CAPS(soc->caps, MTK_SRAM) && eth->scratch_ring) {
>  		dma_free_coherent(eth->dma_dev,
>  				  MTK_QDMA_RING_SIZE * soc->tx.desc_size,
> -- 
> 2.49.0

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