Re: [PATCH] stmmac: enable rx queues

Seraphin BONNAFFE
2016-12-20T14:52:06Z

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@synopsys.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");
>