tests/qtest/ac97-test: add up-/downsampling tests

Test if the audio subsystem can handle extreme up- and down-
sampling ratios like 44100/1 and 1/44100. For some time these
used to trigger QEMU aborts. The test was taken from
https://gitlab.com/qemu-project/qemu/-/issues/71 where it was
used to demonstrate a very different issue.

Suggested-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Volker Rümelin <vr_qemu@t-online.de>
Message-Id: <20230520113313.5177-1-vr_qemu@t-online.de>
Signed-off-by: Thomas Huth <thuth@redhat.com>

tests/qtest/ac97-test.c

@@ -42,16 +42,54 @@ static void *ac97_create(void *pci_bus, QGuestAllocator *alloc, void *addr)
     return &ac97->obj;
 }
 
+/*
+ * This is rather a test of the audio subsystem and not an AC97 test. Test if
+ * the audio subsystem can handle a 44100/1 upsample ratio. For some time this
+ * used to trigger QEMU aborts.
+ */
+static void ac97_playback_upsample(void *obj, void *data, QGuestAllocator *alloc)
+{
+    QAC97 *ac97 = obj;
+    QPCIDevice *dev = &ac97->dev;
+    QPCIBar bar0;
+
+    qpci_device_enable(dev);
+    bar0 = qpci_iomap(dev, 0, NULL);
+    /* IOBAR0 offset 0x2c: PCM Front DAC Rate */
+    qpci_io_writew(dev, bar0, 0x2c, 0x1);
+}
+
+/*
+ * This test is similar to the playback upsample test. QEMU shouldn't abort if
+ * asked for a 1/44100 downsample ratio.
+ */
+static void ac97_record_downsample(void *obj, void *data, QGuestAllocator *alloc)
+{
+    QAC97 *ac97 = obj;
+    QPCIDevice *dev = &ac97->dev;
+    QPCIBar bar0;
+
+    qpci_device_enable(dev);
+    bar0 = qpci_iomap(dev, 0, NULL);
+    /* IOBAR0 offset 0x32: PCM L/R ADC Rate */
+    qpci_io_writew(dev, bar0, 0x32, 0x1);
+}
+
 static void ac97_register_nodes(void)
 {
     QOSGraphEdgeOptions opts = {
-        .extra_device_opts = "addr=04.0",
+        .extra_device_opts = "addr=04.0,audiodev=snd0",
+        .after_cmd_line = "-audiodev none,id=snd0"
+                          ",out.frequency=44100,in.frequency=44100",
     };
     add_qpci_address(&opts, &(QPCIAddress) { .devfn = QPCI_DEVFN(4, 0) });
 
     qos_node_create_driver("AC97", ac97_create);
     qos_node_produces("AC97", "pci-device");
     qos_node_consumes("AC97", "pci-bus", &opts);
+
+    qos_add_test("playback_upsample", "AC97", ac97_playback_upsample, NULL);
+    qos_add_test("record_downsample", "AC97", ac97_record_downsample, NULL);
 }
 
 libqos_init(ac97_register_nodes);