[PATCH net-next] net: bcmgenet: fix Tx ring priority programming

[PATCH net-next] net: bcmgenet: fix Tx ring priority programming

[Petri Gynther]

GENET MAC has three Tx ring priority registers:
- GENET_x_TDMA_PRIORITY0 for queues 0-5
- GENET_x_TDMA_PRIORITY1 for queues 6-11
- GENET_x_TDMA_PRIORITY2 for queues 12-16

Fix bcmgenet_init_multiq() to program them correctly.

Signed-off-by: Petri Gynther <pgynther@google.com>
---
 drivers/net/ethernet/broadcom/genet/bcmgenet.c | 46 +++++++++++++++++---------
 1 file changed, 30 insertions(+), 16 deletions(-)

diff --git a/drivers/net/ethernet/broadcom/genet/bcmgenet.c b/drivers/net/ethernet/broadcom/genet/bcmgenet.c
index e0a6238..151d5b2 100644
--- a/drivers/net/ethernet/broadcom/genet/bcmgenet.c
+++ b/drivers/net/ethernet/broadcom/genet/bcmgenet.c
@@ -191,8 +191,9 @@ enum dma_reg {
 	DMA_STATUS,
 	DMA_SCB_BURST_SIZE,
 	DMA_ARB_CTRL,
-	DMA_PRIORITY,
-	DMA_RING_PRIORITY,
+	DMA_PRIORITY_0,
+	DMA_PRIORITY_1,
+	DMA_PRIORITY_2,
 };
 
 static const u8 bcmgenet_dma_regs_v3plus[] = {
@@ -201,8 +202,9 @@ static const u8 bcmgenet_dma_regs_v3plus[] = {
 	[DMA_STATUS]		= 0x08,
 	[DMA_SCB_BURST_SIZE]	= 0x0C,
 	[DMA_ARB_CTRL]		= 0x2C,
-	[DMA_PRIORITY]		= 0x30,
-	[DMA_RING_PRIORITY]	= 0x38,
+	[DMA_PRIORITY_0]	= 0x30,
+	[DMA_PRIORITY_1]	= 0x34,
+	[DMA_PRIORITY_2]	= 0x38,
 };
 
 static const u8 bcmgenet_dma_regs_v2[] = {
@@ -211,8 +213,9 @@ static const u8 bcmgenet_dma_regs_v2[] = {
 	[DMA_STATUS]		= 0x08,
 	[DMA_SCB_BURST_SIZE]	= 0x0C,
 	[DMA_ARB_CTRL]		= 0x30,
-	[DMA_PRIORITY]		= 0x34,
-	[DMA_RING_PRIORITY]	= 0x3C,
+	[DMA_PRIORITY_0]	= 0x34,
+	[DMA_PRIORITY_1]	= 0x38,
+	[DMA_PRIORITY_2]	= 0x3C,
 };
 
 static const u8 bcmgenet_dma_regs_v1[] = {
@@ -220,8 +223,9 @@ static const u8 bcmgenet_dma_regs_v1[] = {
 	[DMA_STATUS]		= 0x04,
 	[DMA_SCB_BURST_SIZE]	= 0x0C,
 	[DMA_ARB_CTRL]		= 0x30,
-	[DMA_PRIORITY]		= 0x34,
-	[DMA_RING_PRIORITY]	= 0x3C,
+	[DMA_PRIORITY_0]	= 0x34,
+	[DMA_PRIORITY_1]	= 0x38,
+	[DMA_PRIORITY_2]	= 0x3C,
 };
 
 /* Set at runtime once bcmgenet version is known */
@@ -1696,7 +1700,8 @@ static void bcmgenet_init_multiq(struct net_device *dev)
 {
 	struct bcmgenet_priv *priv = netdev_priv(dev);
 	unsigned int i, dma_enable;
-	u32 reg, dma_ctrl, ring_cfg = 0, dma_priority = 0;
+	u32 reg, dma_ctrl, ring_cfg = 0;
+	u32 dma_priority[3] = {0, 0, 0};
 
 	if (!netif_is_multiqueue(dev)) {
 		netdev_warn(dev, "called with non multi queue aware HW\n");
@@ -1721,9 +1726,17 @@ static void bcmgenet_init_multiq(struct net_device *dev)
 
 		/* Configure ring as descriptor ring and setup priority */
 		ring_cfg |= 1 << i;
-		dma_priority |= ((GENET_Q0_PRIORITY + i) <<
-				(GENET_MAX_MQ_CNT + 1) * i);
 		dma_ctrl |= 1 << (i + DMA_RING_BUF_EN_SHIFT);
+
+		if (i < 6)
+			dma_priority[0] |= ((GENET_Q0_PRIORITY + i) <<
+				(i * DMA_RING_BUF_PRIORITY_SHIFT));
+		else if (i < 12)
+			dma_priority[1] |= ((GENET_Q0_PRIORITY + i) <<
+				((i - 6) * DMA_RING_BUF_PRIORITY_SHIFT));
+		else
+			dma_priority[2] |= ((GENET_Q0_PRIORITY + i) <<
+				((i - 12) * DMA_RING_BUF_PRIORITY_SHIFT));
 	}
 
 	/* Enable rings */
@@ -1731,11 +1744,12 @@ static void bcmgenet_init_multiq(struct net_device *dev)
 	reg |= ring_cfg;
 	bcmgenet_tdma_writel(priv, reg, DMA_RING_CFG);
 
-	/* Use configured rings priority and set ring #16 priority */
-	reg = bcmgenet_tdma_readl(priv, DMA_RING_PRIORITY);
-	reg |= ((GENET_Q0_PRIORITY + priv->hw_params->tx_queues) << 20);
-	reg |= dma_priority;
-	bcmgenet_tdma_writel(priv, reg, DMA_PRIORITY);
+	/* Set ring 16 priority and program the hardware registers */
+	dma_priority[2] |=
+		((GENET_Q0_PRIORITY + priv->hw_params->tx_queues) << 20);
+	bcmgenet_tdma_writel(priv, dma_priority[0], DMA_PRIORITY_0);
+	bcmgenet_tdma_writel(priv, dma_priority[1], DMA_PRIORITY_1);
+	bcmgenet_tdma_writel(priv, dma_priority[2], DMA_PRIORITY_2);
 
 	/* Configure ring as descriptor ring and re-enable DMA if enabled */
 	reg = bcmgenet_tdma_readl(priv, DMA_CTRL);
-- 
2.1.0.rc2.206.gedb03e5

Re: [PATCH net-next] net: bcmgenet: fix Tx ring priority programming

[David Miller]

From: Petri Gynther <pgynther@google.com>
Date: Mon,  6 Oct 2014 17:50:01 -0700 (PDT)

> @@ -1731,11 +1744,12 @@ static void bcmgenet_init_multiq(struct net_device *dev)
>  	reg |= ring_cfg;
>  	bcmgenet_tdma_writel(priv, reg, DMA_RING_CFG);
>  
> -	/* Use configured rings priority and set ring #16 priority */
> -	reg = bcmgenet_tdma_readl(priv, DMA_RING_PRIORITY);
> -	reg |= ((GENET_Q0_PRIORITY + priv->hw_params->tx_queues) << 20);
> -	reg |= dma_priority;
> -	bcmgenet_tdma_writel(priv, reg, DMA_PRIORITY);
> +	/* Set ring 16 priority and program the hardware registers */
> +	dma_priority[2] |=
> +		((GENET_Q0_PRIORITY + priv->hw_params->tx_queues) << 20);

Please use "<< (16 - 12) * DMA_RING_BUF_PRIORITY_SHIFT" otherwise this
constant is magic.

You might, optionally, add macros for the subtraction adjustment each
priority register uses (0, 6, 12, respectively).

Re: [PATCH net-next] net: bcmgenet: fix Tx ring priority programming

[Petri Gynther]

Hi David,

On Mon, Oct 6, 2014 at 8:59 PM, David Miller <davem@davemloft.net> wrote:
> From: Petri Gynther <pgynther@google.com>
> Date: Mon,  6 Oct 2014 17:50:01 -0700 (PDT)
>
>> @@ -1731,11 +1744,12 @@ static void bcmgenet_init_multiq(struct net_device *dev)
>>       reg |= ring_cfg;
>>       bcmgenet_tdma_writel(priv, reg, DMA_RING_CFG);
>>
>> -     /* Use configured rings priority and set ring #16 priority */
>> -     reg = bcmgenet_tdma_readl(priv, DMA_RING_PRIORITY);
>> -     reg |= ((GENET_Q0_PRIORITY + priv->hw_params->tx_queues) << 20);
>> -     reg |= dma_priority;
>> -     bcmgenet_tdma_writel(priv, reg, DMA_PRIORITY);
>> +     /* Set ring 16 priority and program the hardware registers */
>> +     dma_priority[2] |=
>> +             ((GENET_Q0_PRIORITY + priv->hw_params->tx_queues) << 20);
>
> Please use "<< (16 - 12) * DMA_RING_BUF_PRIORITY_SHIFT" otherwise this
> constant is magic.
>
> You might, optionally, add macros for the subtraction adjustment each
> priority register uses (0, 6, 12, respectively).

Thanks for the comments. I'm going to simplify this with a few macros.