Date:   Tue, 20 Dec 2016 15:09:46 +0000
From:   Joao Pinto <Joao.Pinto@...opsys.com>
To:     Niklas Cassel <niklas.cassel@...s.com>,
        Joao Pinto <Joao.Pinto@...opsys.com>, <peppe.cavallaro@...com>,
        <davem@...emloft.net>
CC:     <hock.leong.kweh@...el.com>, <pavel@....cz>,
        <linux-kernel@...r.kernel.org>, <netdev@...r.kernel.org>
Subject: Re: [PATCH] stmmac: enable rx queues

Às 3:05 PM de 12/20/2016, Niklas Cassel escreveu:
> 
> 
> On 12/20/2016 03:52 PM, Joao Pinto wrote:
>> Hi Niklas,
>>
>> Às 2:43 PM de 12/20/2016, Niklas Cassel escreveu:
>>>
>>> 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)
>>> Always have parentheses around a variable in a
>>> macro, otherwise strange things could happen.
>>> Imagine if you send 5 - 4 as argument,
>>> it will then expand to 5 - 4 * 2 = -3,
>>> instead of (5 - 4) * 2 = 2
>> Right. I am going to do that.
>>
>>>> +
>>>>  /* 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);
>>>> +
>>>> +	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;
>>> priv->dma_cap.number_rx_channel
>>> actually contains the value from register
>>> MAC_HW_Feature2, field RXCHCNT,
>>> which is the number of DMA rx channels.
>>>
>>> This is not the same as the number of MTL
>>> receive queues, field RXQCNT in MAC_HW_Feature2.
>>>
>>> I guess they will often have the same value,
>>> but since there actually are two different fields
>>> for them, I suppose that is not always the case.
>> Yes, you typically have a match between channels and queues.
>> But I can use RXQCNT of course, I agree.
>>
>>>
>>>
>>> Reading the comments in dwmac4_dma.*
>>>
>>> #define DMA_CHANNEL_NB_MAX              1
>>>
>>> "Only Channel 0 is actually configured and used"
>>>
>>> "Following code only done for channel 0, other channels not yet supported"
>>>
>>> Is there any point in actually enabling more than RX queue 0 if the
>>> driver does not yet support more than one channel.
>>> Can RXCHCNT ever be different from RXQCNT?
>>> If so, when? Maybe when using an external DMA IP?
>> Yes, currently stmmac only supports 1 Channel. Bt it needs this feature if the
>> hardware is multi-channel. The hardware I have is multi-channel and so you have
>> to enable RX queue for it to work and that's why I made this fix.
>> In the future I will develope multi channel support for stmmac and this RX queue
>> enable will be already made.
> 
> I understand that for multi-queue hardware, RX queue 0 is default off,
> but perhaps it is safer to only enable RX queue 0,
> even if you have more than one RX queue.
> (Only until you have implemented actual support for multi-queues
> in the driver.)
> 
> But if you know that it's safe to enable all RX queues even if the
> driver only uses RX queue 0, then perhaps it doesn't matter.

I think it won't bring problems to enable all the available queues even if the
driver only uses queue 0. My QoS reference design has 4 RX queues and it works fine.

> 
> 
>>
>>>
>>>> +	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);
>>>> +}
>>>> +
>>>> +/**
>>>>   *  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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