netdev - Re: [PATCH] net: stmmac: fix rx queue priority assignment

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Message-ID: <nniukwj6oil7hbr2aefvlwicw362h7gotrudarozre35dk3ugm@wjsosr7p27li>
Date: Tue, 20 Feb 2024 13:08:40 +0300
From: Serge Semin <fancer.lancer@...il.com>
To: Piotr Wejman <piotrwejman90@...il.com>
Cc: Alexandre Torgue <alexandre.torgue@...s.st.com>, 
	Jose Abreu <joabreu@...opsys.com>, "David S. Miller" <davem@...emloft.net>, 
	Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>, Maxime Coquelin <mcoquelin.stm32@...il.com>, 
	netdev@...r.kernel.org, linux-stm32@...md-mailman.stormreply.com, 
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] net: stmmac: fix rx queue priority assignment

On Mon, Feb 19, 2024 at 11:24:05AM +0100, Piotr Wejman wrote:
> The driver should ensure that same priority is not mapped to multiple
> rx queues. Currently dwmac4_rx_queue_priority function is adding
> priorities for a queue without clearing them from others.
> 
> From DesignWare Cores Ethernet Quality-of-Service
> Databook, section 17.1.29 MAC_RxQ_Ctrl2:
> "[...]The software must ensure that the content of this field is
> mutually exclusive to the PSRQ fields for other queues, that is,
> the same priority is not mapped to multiple Rx queues[...]"
> 
> After this patch, dwmac4_rx_queue_priority function will:
> - assign desired priorities to a queue
> - remove those priorities from all other queues
> The write sequence of CTRL2 and CTRL3 registers is done in the way to
> ensure this order.
> 

Thanks for the fix. The change in general seems good. The same is
applicable for the DW XGMAC too. Could you please apply it to
dwxgmac2_rx_queue_prio()?

> Also, the PSRQn field contains the mask of priorities and not only one
> priority. Rename "prio" argument to "prio_mask".

Please move this to a separate patch applied on top of the main change
described above. Also in order to be done coherently the renaming
should be extended onto all the Tx/Rx queue prio parts in the
driver:
0. dwmac4_core.c
   +-> dwmac4_rx_queue_priority()
   +-> dwmac4_tx_queue_priority()
1. dwxgmac2_core.c
   +-> dwxgmac2_rx_queue_prio()
   +-> dwxgmac2_tx_queue_prio()
2. hwif.h
   +-> stmmac_ops::rx_queue_prio
   +-> stmmac_ops::tx_queue_prio
3. stmmac.h
   +-> stmmac_rxq_cfg::prio
   +-> stmmac_txq_cfg::prio
4. stmmac_main.c:
   +-> stmmac_mac_config_rx_queues_prio()::prio
   +-> stmmac_mac_config_tx_queues_prio()::prio

* Hope I listed all of them.

-Serge(y)

> 
> Signed-off-by: Piotr Wejman <piotrwejman90@...il.com>
> ---
>  .../net/ethernet/stmicro/stmmac/dwmac4_core.c | 36 +++++++++++++------
>  1 file changed, 26 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac4_core.c b/drivers/net/ethernet/stmicro/stmmac/dwmac4_core.c
> index 6b6d0de09619..6acc8bad794e 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/dwmac4_core.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/dwmac4_core.c
> @@ -89,22 +89,38 @@ static void dwmac4_rx_queue_enable(struct mac_device_info *hw,
>  }
>  
>  static void dwmac4_rx_queue_priority(struct mac_device_info *hw,
> -				     u32 prio, u32 queue)
> +				     u32 prio_mask, u32 queue)
>  {
>  	void __iomem *ioaddr = hw->pcsr;
> -	u32 base_register;
> -	u32 value;
> +	u32 clear_mask = 0;
> +	u32 ctrl2, ctrl3;
> +	int i;
>  
> -	base_register = (queue < 4) ? GMAC_RXQ_CTRL2 : GMAC_RXQ_CTRL3;
> -	if (queue >= 4)
> -		queue -= 4;
> +	ctrl2 = readl(ioaddr + GMAC_RXQ_CTRL2);
> +	ctrl3 = readl(ioaddr + GMAC_RXQ_CTRL3);
>  
> -	value = readl(ioaddr + base_register);
> +	for (i = 0; i < 4; i++)
> +		clear_mask |= ((prio_mask << GMAC_RXQCTRL_PSRQX_SHIFT(i)) &
> +						GMAC_RXQCTRL_PSRQX_MASK(i));
>  
> -	value &= ~GMAC_RXQCTRL_PSRQX_MASK(queue);
> -	value |= (prio << GMAC_RXQCTRL_PSRQX_SHIFT(queue)) &
> +	ctrl2 &= ~clear_mask;
> +	ctrl3 &= ~clear_mask;
> +
> +	if (queue < 4) {
> +		ctrl2 |= (prio_mask << GMAC_RXQCTRL_PSRQX_SHIFT(queue)) &
>  						GMAC_RXQCTRL_PSRQX_MASK(queue);
> -	writel(value, ioaddr + base_register);
> +
> +		writel(ctrl2, ioaddr + GMAC_RXQ_CTRL2);
> +		writel(ctrl3, ioaddr + GMAC_RXQ_CTRL3);
> +	} else {
> +		queue -= 4;
> +
> +		ctrl3 |= (prio_mask << GMAC_RXQCTRL_PSRQX_SHIFT(queue)) &
> +						GMAC_RXQCTRL_PSRQX_MASK(queue);
> +
> +		writel(ctrl3, ioaddr + GMAC_RXQ_CTRL3);
> +		writel(ctrl2, ioaddr + GMAC_RXQ_CTRL2);
> +	}
>  }
>  
>  static void dwmac4_tx_queue_priority(struct mac_device_info *hw,
> -- 
> 2.25.1
> 
>