Merge branch 'stmmac-flow-control'

Vince Bridgers says:

====================
stmmac: Correct flow control configuration

This series of patches corrects flow control configuration for the Synopsys
GMAC driver.

Flow control is configured based on a configurable receive fifo size. If
less than 4Kbytes flow control is left disabled and a warning is presented. If
a receive fifo size is not specified, flow control is left disabled to
maintain current behavior. Unicast pause detection was disabled, but is now
enabled. The pause time was modified to be maximum time per a XON/XOFF
flow control mode of operation.

This patch was tested on an Altera Cyclone 5 and an Altera Arria 10 devkit,
and verified that flow control operates as expected when enabled.

Please consider this series for inclusion so that flow control will
function as expected for the Synopsys GMAC controller.
====================

Acked-by: Giuseppe Cavallaro <peppe.cavallaro@st.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

10 files changed, 111 insertions, 10 deletions

diff --git a/Documentation/devicetree/bindings/net/ethernet.txt b/Documentation/devicetree/bindings/net/ethernet.txt
index 3fc360523bc9..41b3f3f864e8 100644
--- a/Documentation/devicetree/bindings/net/ethernet.txt
+++ b/Documentation/devicetree/bindings/net/ethernet.txt
@@ -19,6 +19,12 @@ The following properties are common to the Ethernet controllers:
 - phy: the same as "phy-handle" property, not recommended for new bindings.
 - phy-device: the same as "phy-handle" property, not recommended for new
   bindings.
+- rx-fifo-depth: the size of the controller's receive fifo in bytes. This
+  is used for components that can have configurable receive fifo sizes,
+  and is useful for determining certain configuration settings such as
+  flow control thresholds.
+- tx-fifo-depth: the size of the controller's transmit fifo in bytes. This
+  is used for components that can have configurable fifo sizes.
 
 Child nodes of the Ethernet controller are typically the individual PHY devices
 connected via the MDIO bus (sometimes the MDIO bus controller is separate).
diff --git a/Documentation/devicetree/bindings/net/stmmac.txt b/Documentation/devicetree/bindings/net/stmmac.txt
index 29aca8591b16..f34fc3c81a75 100644
--- a/Documentation/devicetree/bindings/net/stmmac.txt
+++ b/Documentation/devicetree/bindings/net/stmmac.txt
@@ -45,6 +45,8 @@ Optional properties:
   If not passed then the system clock will be used and this is fine on some
   platforms.
 - snps,burst_len: The AXI burst lenth value of the AXI BUS MODE register.
+- tx-fifo-depth: See ethernet.txt file in the same directory
+- rx-fifo-depth: See ethernet.txt file in the same directory
 
 Examples:
 
@@ -59,6 +61,8 @@ Examples:
 		phy-mode = "gmii";
 		snps,multicast-filter-bins = <256>;
 		snps,perfect-filter-entries = <128>;
+		rx-fifo-depth = <16384>;
+		tx-fifo-depth = <16384>;
 		clocks = <&clock>;
 		clock-names = "stmmaceth";
 	};
diff --git a/drivers/net/ethernet/stmicro/stmmac/common.h b/drivers/net/ethernet/stmicro/stmmac/common.h
index cd77289c3cfe..623c6ed8764a 100644
--- a/drivers/net/ethernet/stmicro/stmmac/common.h
+++ b/drivers/net/ethernet/stmicro/stmmac/common.h
@@ -150,7 +150,7 @@ struct stmmac_extra_stats {
 #define	MAC_CSR_H_FRQ_MASK	0x20
 
 #define HASH_TABLE_SIZE 64
-#define PAUSE_TIME 0x200
+#define PAUSE_TIME 0xffff
 
 /* Flow Control defines */
 #define FLOW_OFF	0
@@ -357,7 +357,8 @@ struct stmmac_dma_ops {
 	void (*dump_regs) (void __iomem *ioaddr);
 	/* Set tx/rx threshold in the csr6 register
 	 * An invalid value enables the store-and-forward mode */
-	void (*dma_mode) (void __iomem *ioaddr, int txmode, int rxmode);
+	void (*dma_mode)(void __iomem *ioaddr, int txmode, int rxmode,
+			 int rxfifosz);
 	/* To track extra statistic (if supported) */
 	void (*dma_diagnostic_fr) (void *data, struct stmmac_extra_stats *x,
 				   void __iomem *ioaddr);
diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac1000.h b/drivers/net/ethernet/stmicro/stmmac/dwmac1000.h
index 64d8f56a9c17..b3fe0575ff6b 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac1000.h
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac1000.h
@@ -172,6 +172,7 @@ enum inter_frame_gap {
 /* GMAC FLOW CTRL defines */
 #define GMAC_FLOW_CTRL_PT_MASK	0xffff0000	/* Pause Time Mask */
 #define GMAC_FLOW_CTRL_PT_SHIFT	16
+#define GMAC_FLOW_CTRL_UP	0x00000008	/* Unicast pause frame enable */
 #define GMAC_FLOW_CTRL_RFE	0x00000004	/* Rx Flow Control Enable */
 #define GMAC_FLOW_CTRL_TFE	0x00000002	/* Tx Flow Control Enable */
 #define GMAC_FLOW_CTRL_FCB_BPA	0x00000001	/* Flow Control Busy ... */
@@ -246,6 +247,56 @@ enum ttc_control {
 #define DMA_CONTROL_FEF		0x00000080
 #define DMA_CONTROL_FUF		0x00000040
 
+/* Receive flow control activation field
+ * RFA field in DMA control register, bits 23,10:9
+ */
+#define DMA_CONTROL_RFA_MASK	0x00800600
+
+/* Receive flow control deactivation field
+ * RFD field in DMA control register, bits 22,12:11
+ */
+#define DMA_CONTROL_RFD_MASK	0x00401800
+
+/* RFD and RFA fields are encoded as follows
+ *
+ *   Bit Field
+ *   0,00 - Full minus 1KB (only valid when rxfifo >= 4KB and EFC enabled)
+ *   0,01 - Full minus 2KB (only valid when rxfifo >= 4KB and EFC enabled)
+ *   0,10 - Full minus 3KB (only valid when rxfifo >= 4KB and EFC enabled)
+ *   0,11 - Full minus 4KB (only valid when rxfifo > 4KB and EFC enabled)
+ *   1,00 - Full minus 5KB (only valid when rxfifo > 8KB and EFC enabled)
+ *   1,01 - Full minus 6KB (only valid when rxfifo > 8KB and EFC enabled)
+ *   1,10 - Full minus 7KB (only valid when rxfifo > 8KB and EFC enabled)
+ *   1,11 - Reserved
+ *
+ * RFD should always be > RFA for a given FIFO size. RFD == RFA may work,
+ * but packet throughput performance may not be as expected.
+ *
+ * Be sure that bit 3 in GMAC Register 6 is set for Unicast Pause frame
+ * detection (IEEE Specification Requirement, Annex 31B, 31B.1, Pause
+ * Description).
+ *
+ * Be sure that DZPA (bit 7 in Flow Control Register, GMAC Register 6),
+ * is set to 0. This allows pause frames with a quanta of 0 to be sent
+ * as an XOFF message to the link peer.
+ */
+
+#define RFA_FULL_MINUS_1K	0x00000000
+#define RFA_FULL_MINUS_2K	0x00000200
+#define RFA_FULL_MINUS_3K	0x00000400
+#define RFA_FULL_MINUS_4K	0x00000600
+#define RFA_FULL_MINUS_5K	0x00800000
+#define RFA_FULL_MINUS_6K	0x00800200
+#define RFA_FULL_MINUS_7K	0x00800400
+
+#define RFD_FULL_MINUS_1K	0x00000000
+#define RFD_FULL_MINUS_2K	0x00000800
+#define RFD_FULL_MINUS_3K	0x00001000
+#define RFD_FULL_MINUS_4K	0x00001800
+#define RFD_FULL_MINUS_5K	0x00400000
+#define RFD_FULL_MINUS_6K	0x00400800
+#define RFD_FULL_MINUS_7K	0x00401000
+
 enum rtc_control {
 	DMA_CONTROL_RTC_64 = 0x00000000,
 	DMA_CONTROL_RTC_32 = 0x00000008,
diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac1000_core.c b/drivers/net/ethernet/stmicro/stmmac/dwmac1000_core.c
index 0adcf73cf722..371a669d69fd 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac1000_core.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac1000_core.c
@@ -201,7 +201,10 @@ static void dwmac1000_flow_ctrl(struct mac_device_info *hw, unsigned int duplex,
 				unsigned int fc, unsigned int pause_time)
 {
 	void __iomem *ioaddr = hw->pcsr;
-	unsigned int flow = 0;
+	/* Set flow such that DZPQ in Mac Register 6 is 0,
+	 * and unicast pause detect is enabled.
+	 */
+	unsigned int flow = GMAC_FLOW_CTRL_UP;
 
 	pr_debug("GMAC Flow-Control:\n");
 	if (fc & FLOW_RX) {
diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac1000_dma.c b/drivers/net/ethernet/stmicro/stmmac/dwmac1000_dma.c
index 59d92e811750..0e8937c1184a 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac1000_dma.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac1000_dma.c
@@ -106,8 +106,29 @@ static int dwmac1000_dma_init(void __iomem *ioaddr, int pbl, int fb, int mb,
 	return 0;
 }
 
+static u32 dwmac1000_configure_fc(u32 csr6, int rxfifosz)
+{
+	csr6 &= ~DMA_CONTROL_RFA_MASK;
+	csr6 &= ~DMA_CONTROL_RFD_MASK;
+
+	/* Leave flow control disabled if receive fifo size is less than
+	 * 4K or 0. Otherwise, send XOFF when fifo is 1K less than full,
+	 * and send XON when 2K less than full.
+	 */
+	if (rxfifosz < 4096) {
+		csr6 &= ~DMA_CONTROL_EFC;
+		pr_debug("GMAC: disabling flow control, rxfifo too small(%d)\n",
+			 rxfifosz);
+	} else {
+		csr6 |= DMA_CONTROL_EFC;
+		csr6 |= RFA_FULL_MINUS_1K;
+		csr6 |= RFD_FULL_MINUS_2K;
+	}
+	return csr6;
+}
+
 static void dwmac1000_dma_operation_mode(void __iomem *ioaddr, int txmode,
-					 int rxmode)
+					 int rxmode, int rxfifosz)
 {
 	u32 csr6 = readl(ioaddr + DMA_CONTROL);
 
@@ -153,6 +174,9 @@ static void dwmac1000_dma_operation_mode(void __iomem *ioaddr, int txmode,
 			csr6 |= DMA_CONTROL_RTC_128;
 	}
 
+	/* Configure flow control based on rx fifo size */
+	csr6 = dwmac1000_configure_fc(csr6, rxfifosz);
+
 	writel(csr6, ioaddr + DMA_CONTROL);
 }
 
diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac100_dma.c b/drivers/net/ethernet/stmicro/stmmac/dwmac100_dma.c
index 7d1dce9e7ffc..9d0971c1c2ee 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac100_dma.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac100_dma.c
@@ -72,7 +72,7 @@ static int dwmac100_dma_init(void __iomem *ioaddr, int pbl, int fb, int mb,
  * control register.
  */
 static void dwmac100_dma_operation_mode(void __iomem *ioaddr, int txmode,
-					int rxmode)
+					int rxmode, int rxfifosz)
 {
 	u32 csr6 = readl(ioaddr + DMA_CONTROL);
 
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 60651738f2a9..05c146f718a3 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -1277,8 +1277,10 @@ static void free_dma_desc_resources(struct stmmac_priv *priv)
  */
 static void stmmac_dma_operation_mode(struct stmmac_priv *priv)
 {
+	int rxfifosz = priv->plat->rx_fifo_size;
+
 	if (priv->plat->force_thresh_dma_mode)
-		priv->hw->dma->dma_mode(priv->ioaddr, tc, tc);
+		priv->hw->dma->dma_mode(priv->ioaddr, tc, tc, rxfifosz);
 	else if (priv->plat->force_sf_dma_mode || priv->plat->tx_coe) {
 		/*
 		 * In case of GMAC, SF mode can be enabled
@@ -1287,10 +1289,12 @@ static void stmmac_dma_operation_mode(struct stmmac_priv *priv)
 		 * 2) There is no bugged Jumbo frame support
 		 *    that needs to not insert csum in the TDES.
 		 */
-		priv->hw->dma->dma_mode(priv->ioaddr, SF_DMA_MODE, SF_DMA_MODE);
+		priv->hw->dma->dma_mode(priv->ioaddr, SF_DMA_MODE, SF_DMA_MODE,
+					rxfifosz);
 		priv->xstats.threshold = SF_DMA_MODE;
 	} else
-		priv->hw->dma->dma_mode(priv->ioaddr, tc, SF_DMA_MODE);
+		priv->hw->dma->dma_mode(priv->ioaddr, tc, SF_DMA_MODE,
+					rxfifosz);
 }
 
 /**
@@ -1442,6 +1446,7 @@ static void stmmac_tx_err(struct stmmac_priv *priv)
 static void stmmac_dma_interrupt(struct stmmac_priv *priv)
 {
 	int status;
+	int rxfifosz = priv->plat->rx_fifo_size;
 
 	status = priv->hw->dma->dma_interrupt(priv->ioaddr, &priv->xstats);
 	if (likely((status & handle_rx)) || (status & handle_tx)) {
@@ -1456,10 +1461,11 @@ static void stmmac_dma_interrupt(struct stmmac_priv *priv)
 		    (tc <= 256)) {
 			tc += 64;
 			if (priv->plat->force_thresh_dma_mode)
-				priv->hw->dma->dma_mode(priv->ioaddr, tc, tc);
+				priv->hw->dma->dma_mode(priv->ioaddr, tc, tc,
+							rxfifosz);
 			else
 				priv->hw->dma->dma_mode(priv->ioaddr, tc,
-					SF_DMA_MODE);
+							SF_DMA_MODE, rxfifosz);
 			priv->xstats.threshold = tc;
 		}
 	} else if (unlikely(status == tx_hard_error))
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
index f9b42f11950f..705bbdf93940 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
@@ -181,6 +181,10 @@ static int stmmac_probe_config_dt(struct platform_device *pdev,
 				     sizeof(struct stmmac_mdio_bus_data),
 				     GFP_KERNEL);
 
+	of_property_read_u32(np, "tx-fifo-depth", &plat->tx_fifo_size);
+
+	of_property_read_u32(np, "rx-fifo-depth", &plat->rx_fifo_size);
+
 	plat->force_sf_dma_mode =
 		of_property_read_bool(np, "snps,force_sf_dma_mode");
 
diff --git a/include/linux/stmmac.h b/include/linux/stmmac.h
index cd63851b57f2..7f484a239f53 100644
--- a/include/linux/stmmac.h
+++ b/include/linux/stmmac.h
@@ -114,6 +114,8 @@ struct plat_stmmacenet_data {
 	int maxmtu;
 	int multicast_filter_bins;
 	int unicast_filter_entries;
+	int tx_fifo_size;
+	int rx_fifo_size;
 	void (*fix_mac_speed)(void *priv, unsigned int speed);
 	void (*bus_setup)(void __iomem *ioaddr);
 	void *(*setup)(struct platform_device *pdev);