net: thunderx: Fix BGX transmit stall due to underflow

For SGMII/RGMII/QSGMII interfaces when physical link goes down
while traffic is high is resulting in underflow condition being set
on that specific BGX's LMAC. Which assets a backpresure and VNIC stops
transmitting packets.

This is due to BGX being disabled in link status change callback while
packet is in transit. This patch fixes this issue by not disabling BGX
but instead just disables packet Rx and Tx.

Signed-off-by: Sunil Goutham <sgoutham@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/cavium/thunder/thunder_bgx.c b/drivers/net/ethernet/cavium/thunder/thunder_bgx.c
index 79112563a25ae08db35bfb2de214c2b3e84a15a6..5e5c4d7796b8882168eba6fe858ac4bfff2aaf53 100644 (file)
--- a/drivers/net/ethernet/cavium/thunder/thunder_bgx.c
+++ b/drivers/net/ethernet/cavium/thunder/thunder_bgx.c
@@ -292,11 +292,30 @@ static void bgx_sgmii_change_link_state(struct lmac *lmac)
        u64 cmr_cfg;
        u64 port_cfg = 0;
        u64 misc_ctl = 0;
+       bool tx_en, rx_en;
 
        cmr_cfg = bgx_reg_read(bgx, lmac->lmacid, BGX_CMRX_CFG);
-       cmr_cfg &= ~CMR_EN;
+       tx_en = cmr_cfg & CMR_PKT_TX_EN;
+       rx_en = cmr_cfg & CMR_PKT_RX_EN;
+       cmr_cfg &= ~(CMR_PKT_RX_EN | CMR_PKT_TX_EN);
        bgx_reg_write(bgx, lmac->lmacid, BGX_CMRX_CFG, cmr_cfg);
 
+       /* Wait for BGX RX to be idle */
+       if (bgx_poll_reg(bgx, lmac->lmacid, BGX_GMP_GMI_PRTX_CFG,
+                        GMI_PORT_CFG_RX_IDLE, false)) {
+               dev_err(&bgx->pdev->dev, "BGX%d LMAC%d GMI RX not idle\n",
+                       bgx->bgx_id, lmac->lmacid);
+               return;
+       }
+
+       /* Wait for BGX TX to be idle */
+       if (bgx_poll_reg(bgx, lmac->lmacid, BGX_GMP_GMI_PRTX_CFG,
+                        GMI_PORT_CFG_TX_IDLE, false)) {
+               dev_err(&bgx->pdev->dev, "BGX%d LMAC%d GMI TX not idle\n",
+                       bgx->bgx_id, lmac->lmacid);
+               return;
+       }
+
        port_cfg = bgx_reg_read(bgx, lmac->lmacid, BGX_GMP_GMI_PRTX_CFG);
        misc_ctl = bgx_reg_read(bgx, lmac->lmacid, BGX_GMP_PCS_MISCX_CTL);
 
@@ -347,10 +366,8 @@ static void bgx_sgmii_change_link_state(struct lmac *lmac)
        bgx_reg_write(bgx, lmac->lmacid, BGX_GMP_PCS_MISCX_CTL, misc_ctl);
        bgx_reg_write(bgx, lmac->lmacid, BGX_GMP_GMI_PRTX_CFG, port_cfg);
 
-       port_cfg = bgx_reg_read(bgx, lmac->lmacid, BGX_GMP_GMI_PRTX_CFG);
-
-       /* Re-enable lmac */
-       cmr_cfg |= CMR_EN;
+       /* Restore CMR config settings */
+       cmr_cfg |= (rx_en ? CMR_PKT_RX_EN : 0) | (tx_en ? CMR_PKT_TX_EN : 0);
        bgx_reg_write(bgx, lmac->lmacid, BGX_CMRX_CFG, cmr_cfg);
 
        if (bgx->is_rgx && (cmr_cfg & (CMR_PKT_RX_EN | CMR_PKT_TX_EN)))

diff --git a/drivers/net/ethernet/cavium/thunder/thunder_bgx.h b/drivers/net/ethernet/cavium/thunder/thunder_bgx.h
index 6b7fe6fdd13b9b27b4a1573e8c7b3869b17bcc19..23acdc5ab896306f3f1e6d2fbc7d8afb58273888 100644 (file)
--- a/drivers/net/ethernet/cavium/thunder/thunder_bgx.h
+++ b/drivers/net/ethernet/cavium/thunder/thunder_bgx.h
@@ -170,6 +170,8 @@
 #define  GMI_PORT_CFG_DUPLEX                   BIT_ULL(2)
 #define  GMI_PORT_CFG_SLOT_TIME                        BIT_ULL(3)
 #define  GMI_PORT_CFG_SPEED_MSB                        BIT_ULL(8)
+#define  GMI_PORT_CFG_RX_IDLE                  BIT_ULL(12)
+#define  GMI_PORT_CFG_TX_IDLE                  BIT_ULL(13)
 #define BGX_GMP_GMI_RXX_JABBER         0x38038
 #define BGX_GMP_GMI_TXX_THRESH         0x38210
 #define BGX_GMP_GMI_TXX_APPEND         0x38218