ALSA: hda - add flags and routines to get devices selection info for DP1.2 MST
This patch adds flags and routines to get device list & selection info on
a pin.
To support Display Port 1.2 multi-stream transport (MST) over single DP port,
a pin can support multiple devices. Please refer to HD-A spec Document Change
Notificaton HDA040-A.
A display audio codec can set flag "dp_mst" in its patch, indicating its pins
can support MST. But at runtime, a pin may not be multi-streaming capable and
report the device list is empty, depending on Gfx driver configuration.
Signed-off-by: Mengdong Lin <mengdong.lin@intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/pci/hda/hda_codec.c b/sound/pci/hda/hda_codec.c
index fdbb09a..5b6c4e3 100644
--- a/sound/pci/hda/hda_codec.c
+++ b/sound/pci/hda/hda_codec.c
@@ -666,6 +666,64 @@
}
EXPORT_SYMBOL_HDA(snd_hda_get_conn_index);
+
+/* return DEVLIST_LEN parameter of the given widget */
+static unsigned int get_num_devices(struct hda_codec *codec, hda_nid_t nid)
+{
+ unsigned int wcaps = get_wcaps(codec, nid);
+ unsigned int parm;
+
+ if (!codec->dp_mst || !(wcaps & AC_WCAP_DIGITAL) ||
+ get_wcaps_type(wcaps) != AC_WID_PIN)
+ return 0;
+
+ parm = snd_hda_param_read(codec, nid, AC_PAR_DEVLIST_LEN);
+ if (parm == -1 && codec->bus->rirb_error)
+ parm = 0;
+ return parm & AC_DEV_LIST_LEN_MASK;
+}
+
+/**
+ * snd_hda_get_devices - copy device list without cache
+ * @codec: the HDA codec
+ * @nid: NID of the pin to parse
+ * @dev_list: device list array
+ * @max_devices: max. number of devices to store
+ *
+ * Copy the device list. This info is dynamic and so not cached.
+ * Currently called only from hda_proc.c, so not exported.
+ */
+int snd_hda_get_devices(struct hda_codec *codec, hda_nid_t nid,
+ u8 *dev_list, int max_devices)
+{
+ unsigned int parm;
+ int i, dev_len, devices;
+
+ parm = get_num_devices(codec, nid);
+ if (!parm) /* not multi-stream capable */
+ return 0;
+
+ dev_len = parm + 1;
+ dev_len = dev_len < max_devices ? dev_len : max_devices;
+
+ devices = 0;
+ while (devices < dev_len) {
+ parm = snd_hda_codec_read(codec, nid, 0,
+ AC_VERB_GET_DEVICE_LIST, devices);
+ if (parm == -1 && codec->bus->rirb_error)
+ break;
+
+ for (i = 0; i < 8; i++) {
+ dev_list[devices] = (u8)parm;
+ parm >>= 4;
+ devices++;
+ if (devices >= dev_len)
+ break;
+ }
+ }
+ return devices;
+}
+
/**
* snd_hda_queue_unsol_event - add an unsolicited event to queue
* @bus: the BUS