From: Ramon Fried <rfried.dev@gmail.com>

Wraparound of TX descriptor cyclic buffer only updated
the low 32 bits of the descriptor.
Fix that by checking if we're working with 64bit descriptors.

Signed-off-by: Ramon Fried <rfried.dev@gmail.com>
Reviewed-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
Message-id: 20200417171736.441607-1-rfried.dev@gmail.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 hw/net/cadence_gem.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/hw/net/cadence_gem.c b/hw/net/cadence_gem.c
index 51ec5a072d0..b7b7985bf26 100644
--- a/hw/net/cadence_gem.c
+++ b/hw/net/cadence_gem.c
@@ -1238,7 +1238,14 @@ static void gem_transmit(CadenceGEMState *s)
             /* read next descriptor */
             if (tx_desc_get_wrap(desc)) {
                 tx_desc_set_last(desc);
-                packet_desc_addr = s->regs[GEM_TXQBASE];
+
+                if (s->regs[GEM_DMACFG] & GEM_DMACFG_ADDR_64B) {
+                    packet_desc_addr = s->regs[GEM_TBQPH];
+                    packet_desc_addr <<= 32;
+                } else {
+                    packet_desc_addr = 0;
+                }
+                packet_desc_addr |= s->regs[GEM_TXQBASE];
             } else {
                 packet_desc_addr += 4 * gem_get_desc_len(s, false);
             }
-- 
2.20.1