net: stmmac: Use correct values in TQS/RQS fields

Currently we are using all the available fifo size in RQS and
TQS fields. This will not work correctly in multi-queues IP's
because total fifo size must be splitted to the enabled queues.

Correct this by computing the available fifo size per queue and
setting the right value in TQS and RQS fields.

Signed-off-by: Jose Abreu <joabreu@synopsys.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Joao Pinto <jpinto@synopsys.com>
Cc: Giuseppe Cavallaro <peppe.cavallaro@st.com>
Cc: Alexandre Torgue <alexandre.torgue@st.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 9 insertions, 6 deletions

diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac4_dma.c b/drivers/net/ethernet/stmicro/stmmac/dwmac4_dma.c
index e84831e1b63b..898849bbc7d4 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac4_dma.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac4_dma.c
@@ -271,9 +271,10 @@ static void dwmac4_dma_rx_chan_op_mode(void __iomem *ioaddr, int mode,
 }
 
 static void dwmac4_dma_tx_chan_op_mode(void __iomem *ioaddr, int mode,
-				       u32 channel)
+				       u32 channel, int fifosz)
 {
 	u32 mtl_tx_op = readl(ioaddr + MTL_CHAN_TX_OP_MODE(channel));
+	unsigned int tqs = fifosz / 256 - 1;
 
 	if (mode == SF_DMA_MODE) {
 		pr_debug("GMAC: enable TX store and forward mode\n");
@@ -306,12 +307,14 @@ static void dwmac4_dma_tx_chan_op_mode(void __iomem *ioaddr, int mode,
 	 * For an IP with DWC_EQOS_NUM_TXQ > 1, the fields TXQEN and TQS are R/W
 	 * with reset values: TXQEN off, TQS 256 bytes.
 	 *
-	 * Write the bits in both cases, since it will have no effect when RO.
-	 * For DWC_EQOS_NUM_TXQ > 1, the top bits in MTL_OP_MODE_TQS_MASK might
-	 * be RO, however, writing the whole TQS field will result in a value
-	 * equal to DWC_EQOS_TXFIFO_SIZE, just like for DWC_EQOS_NUM_TXQ == 1.
+	 * TXQEN must be written for multi-channel operation and TQS must
+	 * reflect the available fifo size per queue (total fifo size / number
+	 * of enabled queues).
 	 */
-	mtl_tx_op |= MTL_OP_MODE_TXQEN | MTL_OP_MODE_TQS_MASK;
+	mtl_tx_op |= MTL_OP_MODE_TXQEN;
+	mtl_tx_op &= ~MTL_OP_MODE_TQS_MASK;
+	mtl_tx_op |= tqs << MTL_OP_MODE_TQS_SHIFT;
+
 	writel(mtl_tx_op, ioaddr +  MTL_CHAN_TX_OP_MODE(channel));
 }