Re: [alsa-devel] [PATCH 03/14] ALSA: hdac: Fix codec name after machine driver is unloaded and reloaded

From: Pierre-Louis Bossart
Date: Wed Jun 05 2019 - 11:17:37 EST

On 6/5/19 8:45 AM, Amadeusz SÅawiÅski wrote:
From: Amadeusz SÅawiÅski <amadeuszx.slawinski@xxxxxxxxx>

This resets internal index used for enumarating codecs. This will only
work on assumption that platform has one codec. Anyway if there is more,
it won't work with current machine drivers, because we can't guarantee
order in which they are enumerated. This workarounds the fact that most
intel machine drivers have the following defined:
.codec_name = "ehdaudio0D2",
However when we unload and reload machine driver idx gets incremented,
so .codec_name would've needed to be set to ehdaudio1D2 on first reload
and so on.

Signed-off-by: Amadeusz SÅawiÅski <amadeuszx.slawinski@xxxxxxxxx>
sound/hda/ext/hdac_ext_bus.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/sound/hda/ext/hdac_ext_bus.c b/sound/hda/ext/hdac_ext_bus.c
index f33ba58b753c..c84d69c2eba4 100644
--- a/sound/hda/ext/hdac_ext_bus.c
+++ b/sound/hda/ext/hdac_ext_bus.c
@@ -77,6 +77,8 @@ static const struct hdac_io_ops hdac_ext_default_io = {
.dma_free_pages = hdac_ext_dma_free_pages,
+static int idx;
* snd_hdac_ext_bus_init - initialize a HD-audio extended bus
* @ebus: the pointer to extended bus object
@@ -93,7 +95,6 @@ int snd_hdac_ext_bus_init(struct hdac_bus *bus, struct device *dev,
const struct hdac_ext_bus_ops *ext_ops)
int ret;
- static int idx;
/* check if io ops are provided, if not load the defaults */
if (io_ops == NULL)
@@ -118,6 +119,14 @@ EXPORT_SYMBOL_GPL(snd_hdac_ext_bus_init);
void snd_hdac_ext_bus_exit(struct hdac_bus *bus)
+ /* FIXME: this is workaround
+ * reset index used for bus->idx, because machine drivers expect
+ * the codec name to be ehdaudio0D2, where 0 is bus->idx
+ * we only perform reset if there is one used device, if there is more
+ * all bets are off
+ */
+ if (idx == 1)
+ idx = 0;

The real fix would be to stop incrementing idx in snd_hdac_ext_bus_init, which would make sense only if we had multiple controllers. SOF pegged bus->idx to zero.