Loopback mode only works when specific conditions (as dictated by the
IP guide) are met, i.e. the MII_MODE is set and the RMII_MODE is
cleared. If not, we simply send the packet on the output queue (for TX
to the host network). Tested by running a custom RTOS and TXing a ton
of packets. The same packets were received on the RX side..
Signed-off-by: Bilal Wasim <address@hidden>
---
hw/net/imx_fec.c | 27 +++++++++++++++++++++++++--
1 file changed, 25 insertions(+), 2 deletions(-)
diff --git a/hw/net/imx_fec.c b/hw/net/imx_fec.c index
bd99236864..c51e7f7363 100644
--- a/hw/net/imx_fec.c
+++ b/hw/net/imx_fec.c
@@ -256,6 +256,29 @@ static const VMStateDescription vmstate_imx_eth =
{
static void imx_eth_update(IMXFECState *s);
+/*
+ * Function to check if the MAC is configured to run in loopback mode.
+ * If so, invoke the "receive" routine.
+ * Else write to the output.
+ * */
+static void send_pkt(IMXFECState *s, uint8_t *frame, int frame_size)
+{
+ NetClientState *nc = qemu_get_queue(s->nic);
+
+ /*
+ * Loopback or Normal mode ?
+ * Per the FEC Manual: If loopback is enabled, the MII_MODE
+ * should be SET and the RMII_MODE should be cleared. Loopback
+ * will only work if this criterion is met. If not met,
+ * we will send the frame on the output queue. */
+ if ((s->regs[ENET_RCR] & ENET_RCR_LOOP) && (s->regs[ENET_RCR] &
ENET_RCR_MII_MODE)
+ && !(s->regs[ENET_RCR] & ENET_RCR_RMII_MODE)) {
+ nc->info->receive(nc, frame, frame_size);
+ } else {
+ qemu_send_packet(nc, frame, frame_size);
+ }
+}
+
/*
* The MII phy could raise a GPIO to the processor which in turn
* could be handled as an interrpt by the OS.
@@ -488,7 +511,7 @@ static void imx_fec_do_tx(IMXFECState *s)
frame_size += len;
if (bd.flags & ENET_BD_L) {
/* Last buffer in frame. */
- qemu_send_packet(qemu_get_queue(s->nic), s->frame, frame_size);
+ send_pkt(s, (uint8_t *)&s->frame, frame_size);
ptr = s->frame;
frame_size = 0;
s->regs[ENET_EIR] |= ENET_INT_TXF; @@ -586,7 +609,7 @@
static void imx_enet_do_tx(IMXFECState *s, uint32_t index)
}
/* Last buffer in frame. */
- qemu_send_packet(qemu_get_queue(s->nic), s->frame, frame_size);
+ send_pkt(s, (uint8_t *)&s->frame, frame_size);
ptr = s->frame;
frame_size = 0;