driver:net:stmmac: Disable DMA store and forward mode if platform data force_thresh_dma_mode is set.

Some synopsys ip implementation doesn't support DMA store and forward mode,
such as BF60x. So, set force_thresh_dma_mode to use DMA thresholds only.
Update document and devicetree as well.

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

Documentation/devicetree/bindings/net/stmmac.txt

@@ -22,6 +22,11 @@ Required properties:
 - snps,pbl		Programmable Burst Length
 - snps,fixed-burst	Program the DMA to use the fixed burst mode
 - snps,mixed-burst	Program the DMA to use the mixed burst mode
+- snps,force_thresh_dma_mode	Force DMA to use the threshold mode for
+				both tx and rx
+- snps,force_sf_dma_mode	Force DMA to use the Store and Forward
+				mode for both tx and rx. This flag is
+				ignored if force_thresh_dma_mode is set.
 
 Optional properties:
 - mac-address: 6 bytes, mac address

Documentation/networking/stmmac.txt

@@ -123,6 +123,7 @@ struct plat_stmmacenet_data {
 	int bugged_jumbo;
 	int pmt;
 	int force_sf_dma_mode;
+	int force_thresh_dma_mode;
 	int riwt_off;
 	void (*fix_mac_speed)(void *priv, unsigned int speed);
 	void (*bus_setup)(void __iomem *ioaddr);
@@ -159,6 +160,8 @@ Where:
  o pmt: core has the embedded power module (optional).
  o force_sf_dma_mode: force DMA to use the Store and Forward mode
 		     instead of the Threshold.
+ o force_thresh_dma_mode: force DMA to use the Shreshold mode other than
+		     the Store and Forward mode.
  o riwt_off: force to disable the RX watchdog feature and switch to NAPI mode.
  o fix_mac_speed: this callback is used for modifying some syscfg registers
 		 (on ST SoCs) according to the link speed negotiated by the

drivers/net/ethernet/stmicro/stmmac/stmmac_main.c

@@ -1224,7 +1224,9 @@ static void free_dma_desc_resources(struct stmmac_priv *priv)
  */
 static void stmmac_dma_operation_mode(struct stmmac_priv *priv)
 {
-	if (priv->plat->force_sf_dma_mode || priv->plat->tx_coe) {
+	if (priv->plat->force_thresh_dma_mode)
+		priv->hw->dma->dma_mode(priv->ioaddr, tc, tc);
+	else if (priv->plat->force_sf_dma_mode || priv->plat->tx_coe) {
 		/*
 		 * In case of GMAC, SF mode can be enabled
 		 * to perform the TX COE in HW. This depends on:

drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c

@@ -79,6 +79,11 @@ static int stmmac_probe_config_dt(struct platform_device *pdev,
 	of_property_read_u32(np, "snps,pbl", &dma_cfg->pbl);
 	dma_cfg->fixed_burst = of_property_read_bool(np, "snps,fixed-burst");
 	dma_cfg->mixed_burst = of_property_read_bool(np, "snps,mixed-burst");
+	plat->force_thresh_dma_mode = of_property_read_bool(np, "snps,force_thresh_dma_mode");
+	if (plat->force_thresh_dma_mode) {
+		plat->force_sf_dma_mode = 0;
+		pr_warn("force_sf_dma_mode is ignored if force_thresh_dma_mode is set.");
+	}
 
 	return 0;
 }

include/linux/stmmac.h

@@ -108,6 +108,7 @@ struct plat_stmmacenet_data {
 	int bugged_jumbo;
 	int pmt;
 	int force_sf_dma_mode;
+	int force_thresh_dma_mode;
 	int riwt_off;
 	void (*fix_mac_speed)(void *priv, unsigned int speed);
 	void (*bus_setup)(void __iomem *ioaddr);