[PATCH v2 17/19] hw/net/bcm2838_genet: fix TX ring activation check

[Marcelo Manzo <marcelomanzo@gmail.com>]

bcm2838_genet_tdma_ring_active() extracted the per-ring enable bit
from ring_cfg_reg using the GENET_DMA_CTRL register's EN field
definition (1 bit wide, at bit 0) instead of GENET_DMA_RING_CFG's
own EN field (17 bits wide, one bit per ring). Since a 1-bit
extraction at bit 0 only ever reflects ring 0's enable bit, every
other ring (1-15, and the default ring 16) was silently treated as
inactive regardless of whether the driver had actually enabled it.
TX traffic hashed onto those queues was dropped with no error,
eventually tripping the guest's qdisc watchdog ("NETDEV WATCHDOG:
transmit queue N timed out") and causing intermittent DHCP failure /
link-local address fallback.

bcm2838_genet_rdma_ring_active(), the RX equivalent, already used
the correct field, confirming this was a copy-paste error isolated
to the TX path.

Confirmed fixed across repeated boots: real DHCP lease every time,
0% ping loss, no more checksum or watchdog messages in dmesg.

Signed-off-by: Marcelo Manzo <marcelomanzo@gmail.com>
---
 hw/net/bcm2838_genet.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hw/net/bcm2838_genet.c b/hw/net/bcm2838_genet.c
index ccf3c2fef0..bb967ad845 100644
--- a/hw/net/bcm2838_genet.c
+++ b/hw/net/bcm2838_genet.c
@@ -517,7 +517,7 @@ static bool bcm2838_genet_tdma_ring_active(BCM2838GenetState *s,
     uint32_t ring_mask = 1 << ring_index;
     bool dma_en = FIELD_EX32(ctrl_reg, GENET_DMA_CTRL, EN) != 0;
     bool ring_en =
-        (FIELD_EX32(ring_cfg_reg, GENET_DMA_CTRL, EN) & ring_mask) != 0;
+        (FIELD_EX32(ring_cfg_reg, GENET_DMA_RING_CFG, EN) & ring_mask) != 0;
     bool ring_buf_en =
         (FIELD_EX32(ctrl_reg, GENET_DMA_CTRL, RING_BUF_EN) & ring_mask) != 0;
     bool active = dma_en && ring_en && ring_buf_en;
-- 
2.47.1