net/npcm7xx_emc.c: Fix handling of receiving packets when RSDR not set

Turning REG_MCMDR_RXON is enough to start receiving packets.

Signed-off-by: Doug Evans <dje@google.com>
Message-id: 20210319195044.741821-1-dje@google.com
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

hw/net/npcm7xx_emc.c

@@ -702,7 +702,9 @@ static void npcm7xx_emc_write(void *opaque, hwaddr offset,
                    !(value & REG_MCMDR_RXON)) {
             emc->regs[REG_MGSTA] |= REG_MGSTA_RXHA;
         }
-        if (!(value & REG_MCMDR_RXON)) {
+        if (value & REG_MCMDR_RXON) {
+            emc->rx_active = true;
+        } else {
             emc_halt_rx(emc, 0);
         }
         break;

tests/qtest/npcm7xx_emc-test.c

@@ -492,9 +492,6 @@ static void enable_tx(QTestState *qts, const EMCModule *mod,
         mcmdr |= REG_MCMDR_TXON;
         emc_write(qts, mod, REG_MCMDR, mcmdr);
     }
-
-    /* Prod the device to send the packet. */
-    emc_write(qts, mod, REG_TSDR, 1);
 }
 
 static void emc_send_verify1(QTestState *qts, const EMCModule *mod, int fd,
@@ -558,6 +555,9 @@ static void emc_send_verify(QTestState *qts, const EMCModule *mod, int fd,
     enable_tx(qts, mod, &desc[0], NUM_TX_DESCRIPTORS, desc_addr,
               with_irq ? REG_MIEN_ENTXINTR : 0);
 
+    /* Prod the device to send the packet. */
+    emc_write(qts, mod, REG_TSDR, 1);
+
     /*
      * It's problematic to observe the interrupt for each packet.
      * Instead just wait until all the packets go out.
@@ -643,13 +643,10 @@ static void enable_rx(QTestState *qts, const EMCModule *mod,
         mcmdr |= REG_MCMDR_RXON | mcmdr_flags;
         emc_write(qts, mod, REG_MCMDR, mcmdr);
     }
-
-    /* Prod the device to accept a packet. */
-    emc_write(qts, mod, REG_RSDR, 1);
 }
 
 static void emc_recv_verify(QTestState *qts, const EMCModule *mod, int fd,
-                            bool with_irq)
+                            bool with_irq, bool pump_rsdr)
 {
     NPCM7xxEMCRxDesc desc[NUM_RX_DESCRIPTORS];
     uint32_t desc_addr = DESC_ADDR;
@@ -679,6 +676,15 @@ static void emc_recv_verify(QTestState *qts, const EMCModule *mod, int fd,
     enable_rx(qts, mod, &desc[0], NUM_RX_DESCRIPTORS, desc_addr,
               with_irq ? REG_MIEN_ENRXINTR : 0, 0);
 
+    /*
+     * If requested, prod the device to accept a packet.
+     * This isn't necessary, the linux driver doesn't do this.
+     * Test doing/not-doing this for robustness.
+     */
+    if (pump_rsdr) {
+        emc_write(qts, mod, REG_RSDR, 1);
+    }
+
     /* Send test packet to device's socket. */
     ret = iov_send(fd, iov, 2, 0, sizeof(len) + sizeof(test));
     g_assert_cmpint(ret, == , sizeof(test) + sizeof(len));
@@ -826,8 +832,14 @@ static void test_rx(gconstpointer test_data)
 
     qtest_irq_intercept_in(qts, "/machine/soc/a9mpcore/gic");
 
-    emc_recv_verify(qts, td->module, test_sockets[0], /*with_irq=*/false);
-    emc_recv_verify(qts, td->module, test_sockets[0], /*with_irq=*/true);
+    emc_recv_verify(qts, td->module, test_sockets[0], /*with_irq=*/false,
+                    /*pump_rsdr=*/false);
+    emc_recv_verify(qts, td->module, test_sockets[0], /*with_irq=*/false,
+                    /*pump_rsdr=*/true);
+    emc_recv_verify(qts, td->module, test_sockets[0], /*with_irq=*/true,
+                    /*pump_rsdr=*/false);
+    emc_recv_verify(qts, td->module, test_sockets[0], /*with_irq=*/true,
+                    /*pump_rsdr=*/true);
     emc_test_ptle(qts, td->module, test_sockets[0]);
 
     qtest_quit(qts);