If the maximum payload size is 256 bytes or more, set the DMA write

water mark to 256 bytes.  Otherwise controller will encounter DMA
write under run errors and would result in RX DMA hang. If the
maximum payload size is 128 bytes, the water mark is set to 128
bytes as usual.
While here, set maximum read request size to 2048 for BCM5719/BCM5720.
For other PCIe devices, use 4096. And reprogram the maximum read
request size whenever device reset is performed.

2 files changed, 15 insertions, 5 deletions

diff --git a/sys/dev/bge/if_bge.c b/sys/dev/bge/if_bge.c
index cc30b14..44ff518 100644
--- a/sys/dev/bge/if_bge.c
+++ b/sys/dev/bge/if_bge.c
@@ -1466,8 +1466,10 @@ bge_chipinit(struct bge_softc *sc)
 	dma_rw_ctl = BGE_PCIDMARWCTL_RD_CMD_SHIFT(6) |
 	    BGE_PCIDMARWCTL_WR_CMD_SHIFT(7);
 	if (sc->bge_flags & BGE_FLAG_PCIE) {
-		/* Read watermark not used, 128 bytes for write. */
-		dma_rw_ctl |= BGE_PCIDMARWCTL_WR_WAT_SHIFT(3);
+		if (sc->bge_mps >= 256)
+			dma_rw_ctl |= BGE_PCIDMARWCTL_WR_WAT_SHIFT(7);
+		else
+			dma_rw_ctl |= BGE_PCIDMARWCTL_WR_WAT_SHIFT(3);
 	} else if (sc->bge_flags & BGE_FLAG_PCIX) {
 		if (BGE_IS_5714_FAMILY(sc)) {
 			/* 256 bytes for read and write. */
@@ -3161,11 +3163,16 @@ bge_attach(device_t dev)
 		 */
 		sc->bge_flags |= BGE_FLAG_PCIE;
 		sc->bge_expcap = reg;
+		/* Extract supported maximum payload size. */
+		sc->bge_mps = pci_read_config(dev, sc->bge_expcap +
+		    PCIER_DEVICE_CAP, 2);
+		sc->bge_mps = 128 << (sc->bge_mps & PCIEM_CAP_MAX_PAYLOAD);
 		if (sc->bge_asicrev == BGE_ASICREV_BCM5719 ||
 		    sc->bge_asicrev == BGE_ASICREV_BCM5720)
-			pci_set_max_read_req(dev, 2048);
-		else if (pci_get_max_read_req(dev) != 4096)
-			pci_set_max_read_req(dev, 4096);
+			sc->bge_expmrq = 2048;
+		else
+			sc->bge_expmrq = 4096;
+		pci_set_max_read_req(dev, sc->bge_expmrq);
 	} else {
 		/*
 		 * Check if the device is in PCI-X Mode.
@@ -3642,6 +3649,7 @@ bge_reset(struct bge_softc *sc)
 		    PCIEM_CTL_NOSNOOP_ENABLE);
 		pci_write_config(dev, sc->bge_expcap + PCIER_DEVICE_CTL,
 		    devctl, 2);
+		pci_set_max_read_req(dev, sc->bge_expmrq);
 		/* Clear error status. */
 		pci_write_config(dev, sc->bge_expcap + PCIER_DEVICE_STA,
 		    PCIEM_STA_CORRECTABLE_ERROR |
diff --git a/sys/dev/bge/if_bgereg.h b/sys/dev/bge/if_bgereg.h
index ab70692..88627c2 100644
--- a/sys/dev/bge/if_bgereg.h
+++ b/sys/dev/bge/if_bgereg.h
@@ -2792,6 +2792,7 @@ struct bge_softc {
 	struct resource		*bge_res;
 	struct ifmedia		bge_ifmedia;	/* TBI media info */
 	int			bge_expcap;
+	int			bge_expmrq;
 	int			bge_msicap;
 	int			bge_pcixcap;
 	uint32_t		bge_flags;
@@ -2835,6 +2836,7 @@ struct bge_softc {
 	uint32_t		bge_chiprev;
 	uint8_t			bge_asf_mode;
 	uint8_t			bge_asf_count;
+	uint16_t		bge_mps;
 	struct bge_ring_data	bge_ldata;	/* rings */
 	struct bge_chain_data	bge_cdata;	/* mbufs */
 	uint16_t		bge_tx_saved_considx;