Date:   Tue, 20 Dec 2016 15:52:06 +0100
From:   Seraphin BONNAFFE <seraphin.bonnaffe@...com>
To:     Joao Pinto <Joao.Pinto@...opsys.com>, <peppe.cavallaro@...com>,
        <davem@...emloft.net>
CC:     <hock.leong.kweh@...el.com>, <niklas.cassel@...s.com>,
        <pavel@....cz>, <linux-kernel@...r.kernel.org>,
        <netdev@...r.kernel.org>
Subject: Re: [PATCH] stmmac: enable rx queues

Hi Joao,

Please see my in-line comments.

Regards,
Séraphin
--
Seraphin BONNAFFE | Tel: +33244027061
STMicroelectronics | ADG | S/W Design

On 12/20/2016 01:55 PM, Joao Pinto wrote:
> When the hardware is synthesized with multiple queues, all queues are
> disabled for default. This patch adds the rx queues configuration.
> This patch was successfully tested in a Synopsys QoS Reference design.
>
> Signed-off-by: Joao Pinto <jpinto@...opsys.com>
> ---
>  drivers/net/ethernet/stmicro/stmmac/common.h      |  2 ++
>  drivers/net/ethernet/stmicro/stmmac/dwmac4.h      |  4 ++++
>  drivers/net/ethernet/stmicro/stmmac/dwmac4_core.c | 11 +++++++++++
>  drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 21 +++++++++++++++++++++
>  4 files changed, 38 insertions(+)
>
> diff --git a/drivers/net/ethernet/stmicro/stmmac/common.h b/drivers/net/ethernet/stmicro/stmmac/common.h
> index b13a144..61bab50 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/common.h
> +++ b/drivers/net/ethernet/stmicro/stmmac/common.h
> @@ -454,6 +454,8 @@ struct stmmac_ops {
>  	void (*core_init)(struct mac_device_info *hw, int mtu);
>  	/* Enable and verify that the IPC module is supported */
>  	int (*rx_ipc)(struct mac_device_info *hw);
> +	/* Enable RX Queues */
> +	void (*rx_queue_enable)(struct mac_device_info *hw, u32 queue);
>  	/* Dump MAC registers */
>  	void (*dump_regs)(struct mac_device_info *hw);
>  	/* Handle extra events on specific interrupts hw dependent */
> diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac4.h b/drivers/net/ethernet/stmicro/stmmac/dwmac4.h
> index 3e8d4fe..fd013bd 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/dwmac4.h
> +++ b/drivers/net/ethernet/stmicro/stmmac/dwmac4.h
> @@ -22,6 +22,7 @@
>  #define GMAC_HASH_TAB_32_63		0x00000014
>  #define GMAC_RX_FLOW_CTRL		0x00000090
>  #define GMAC_QX_TX_FLOW_CTRL(x)		(0x70 + x * 4)
> +#define GMAC_RXQ_CTRL0			0x000000a0
>  #define GMAC_INT_STATUS			0x000000b0
>  #define GMAC_INT_EN			0x000000b4
>  #define GMAC_PCS_BASE			0x000000e0
> @@ -44,6 +45,9 @@
>
>  #define GMAC_MAX_PERFECT_ADDRESSES	128
>
> +/* MAC RX Queue Enable*/
> +#define GMAC_RX_QUEUE_ENABLE(queue)	BIT(queue * 2)

According to the GMAC_RXQ0 register description from the dwc_ether_qos_databok, I guess this will enable the queues in AV only.
What if we would like to enable them in DCB (10)b ?


> +
>  /* MAC Flow Control RX */
>  #define GMAC_RX_FLOW_CTRL_RFE		BIT(0)
>
> diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac4_core.c b/drivers/net/ethernet/stmicro/stmmac/dwmac4_core.c
> index eaed7cb..7ec1887 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/dwmac4_core.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/dwmac4_core.c
> @@ -59,6 +59,16 @@ static void dwmac4_core_init(struct mac_device_info *hw, int mtu)
>  	writel(value, ioaddr + GMAC_INT_EN);
>  }
>
> +static void dwmac4_rx_queue_enable(struct mac_device_info *hw, u32 queue)
> +{
> +	void __iomem *ioaddr = hw->pcsr;
> +	u32 value = readl(ioaddr + GMAC_RXQ_CTRL0);
> +
> +	value |= GMAC_RX_QUEUE_ENABLE(queue);

What happen if for some reason the previous value of the register was 0xffff ?
The OR mask, by itself, won't clear the bits. AFAIU each queue is enabled with a 2-bit value, and (11)b don't have the same effect as (01)b, does it ?

I would suggest to clear the RXQ-enable bits before writing a new value.
Something like
   value &= GMAC_RX_QUEUE_CLEAR(queue)
   value |= GMAC_RX_QUEUE_ENABLE(queue);

What do you think about that ?

> +
> +	writel(value, ioaddr + GMAC_RXQ_CTRL0);
> +}
> +
>  static void dwmac4_dump_regs(struct mac_device_info *hw)
>  {
>  	void __iomem *ioaddr = hw->pcsr;
> @@ -392,6 +402,7 @@ static void dwmac4_debug(void __iomem *ioaddr, struct stmmac_extra_stats *x)
>  static const struct stmmac_ops dwmac4_ops = {
>  	.core_init = dwmac4_core_init,
>  	.rx_ipc = dwmac4_rx_ipc_enable,
> +	.rx_queue_enable = dwmac4_rx_queue_enable,
>  	.dump_regs = dwmac4_dump_regs,
>  	.host_irq_status = dwmac4_irq_status,
>  	.flow_ctrl = dwmac4_flow_ctrl,
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> index 3e40578..e30034d 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> @@ -1271,6 +1271,24 @@ static void free_dma_desc_resources(struct stmmac_priv *priv)
>  }
>
>  /**
> + *  stmmac_mac_enable_rx_queues - Enable MAC rx queues
> + *  @priv: driver private structure
> + *  Description: It is used for enabling the rx queues in the MAC
> + */
> +static void stmmac_mac_enable_rx_queues(struct stmmac_priv *priv)
> +{
> +	int rx_count = priv->dma_cap.number_rx_channel;
> +	int queue = 0;
> +
> +	/* If GMAC does not have multiqueues, then this is not necessary*/
> +	if (rx_count == 1)
> +		return;
> +
> +	for (queue = 0; queue < rx_count; queue++)
> +		priv->hw->mac->rx_queue_enable(priv->hw, queue);


Maybe it is worth checking if (priv->hw->mac->rx_queue_enable)
before actually calling this callback ?
I can see you have implemented it for dwmac4, but not for dwmac100 and dwmac100
In that case we may have a null pointer exception here.

> +}
> +
> +/**
>   *  stmmac_dma_operation_mode - HW DMA operation mode
>   *  @priv: driver private structure
>   *  Description: it is used for configuring the DMA operation mode register in
> @@ -1691,6 +1709,9 @@ static int stmmac_hw_setup(struct net_device *dev, bool init_ptp)
>  	/* Initialize the MAC Core */
>  	priv->hw->mac->core_init(priv->hw, dev->mtu);
>
> +	/* Initialize MAC RX Queues */
> +	stmmac_mac_enable_rx_queues(priv);
> +
>  	ret = priv->hw->mac->rx_ipc(priv->hw);
>  	if (!ret) {
>  		netdev_warn(priv->dev, "RX IPC Checksum Offload disabled\n");
>

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