[alsa-devel] [PATCH v3 12/13] ALSA: hdac: ext: add wait for codec to respond after link reset

[Pierre-Louis Bossart]

From: Rakesh Ughreja <rakesh.a.ughreja at intel.com>

As per HDA spec section 4.3 - Codec Discovery, the software shall wait
for atleast 521usec for codec to respond after link reset.
With the multi-link capability each link is turned ON/OFF individually.
Link controller drives reset signal when it is turned ON.

Signed-off-by: Rakesh Ughreja <rakesh.a.ughreja at intel.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart at linux.intel.com>
---
 sound/hda/ext/hdac_ext_controller.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/sound/hda/ext/hdac_ext_controller.c b/sound/hda/ext/hdac_ext_controller.c
index 72774119dd11..5bc4a1d587d4 100644
--- a/sound/hda/ext/hdac_ext_controller.c
+++ b/sound/hda/ext/hdac_ext_controller.c
@@ -271,6 +271,15 @@ int snd_hdac_ext_bus_link_get(struct hdac_bus *bus,
 		}
 
 		ret = snd_hdac_ext_bus_link_power_up(link);
+
+		/*
+		 *  wait for 521usec for codec to report status
+		 *  HDA spec section 4.3 - Codec Discovery
+		 */
+		udelay(521);
+		bus->codec_mask = snd_hdac_chip_readw(bus, STATESTS);
+		dev_dbg(bus->dev, "codec_mask = 0x%lx\n", bus->codec_mask);
+		snd_hdac_chip_writew(bus, STATESTS, bus->codec_mask);
 	}
 
 	mutex_unlock(&bus->lock);
-- 
2.14.1