On Mon, 21 Mar 2016 09:37:54 +0100, libin.yang@linux.intel.com wrote:
From: Libin Yang libin.yang@linux.intel.com
Add snd_hda_get_dev_select() and snd_hda_set_dev_select() functions for DP MST audio support.
Signed-off-by: Libin Yang libin.yang@linux.intel.com
sound/pci/hda/hda_codec.c | 83 ++++++++++++++++++++++++++++++++++++++++++++--- sound/pci/hda/hda_codec.h | 3 ++ 2 files changed, 82 insertions(+), 4 deletions(-)
diff --git a/sound/pci/hda/hda_codec.c b/sound/pci/hda/hda_codec.c index d17e38e..db94a66 100644 --- a/sound/pci/hda/hda_codec.c +++ b/sound/pci/hda/hda_codec.c @@ -325,9 +325,16 @@ int snd_hda_get_conn_index(struct hda_codec *codec, hda_nid_t mux, } EXPORT_SYMBOL_GPL(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) +/**
- snd_hda_get_num_devices - get DEVLIST_LEN parameter of the given widget
- @codec: the HDA codec
- @nid: NID of the pin to parse
- Get the device entry number on the given widget.
- This is a feature of DP MST audio. Each pin can
- have several device entries in it.
- */
+unsigned int snd_hda_get_num_devices(struct hda_codec *codec, hda_nid_t nid) { unsigned int wcaps = get_wcaps(codec, nid); unsigned int parm; @@ -341,6 +348,7 @@ static unsigned int get_num_devices(struct hda_codec *codec, hda_nid_t nid) parm = 0; return parm & AC_DEV_LIST_LEN_MASK; } +EXPORT_SYMBOL_GPL(snd_hda_get_num_devices);
/**
- snd_hda_get_devices - copy device list without cache
@@ -358,7 +366,7 @@ int snd_hda_get_devices(struct hda_codec *codec, hda_nid_t nid, unsigned int parm; int i, dev_len, devices;
- parm = get_num_devices(codec, nid);
- parm = snd_hda_get_num_devices(codec, nid); if (!parm) /* not multi-stream capable */ return 0;
@@ -382,6 +390,73 @@ int snd_hda_get_devices(struct hda_codec *codec, hda_nid_t nid, return devices; }
+/**
- snd_hda_get_dev_select - get device entry select on the pin
- @codec: the HDA codec
- @nid: NID of the pin to get device entry select
- Get the devcie entry select on the pin. Return the device entry
- id selected on the pin. Return 0 means the first device entry
- is selected or MST is not supported.
- */
+int snd_hda_get_dev_select(struct hda_codec *codec, hda_nid_t nid) +{
- /* not support dp_mst will always return 0, using first dev_entry */
- if (!codec->dp_mst)
return 0;- return snd_hda_codec_read(codec, nid, 0, AC_VERB_GET_DEVICE_SEL, 0);
+} +EXPORT_SYMBOL_GPL(snd_hda_get_dev_select);
+/**
- snd_hda_set_dev_select - set device entry select on the pin
- @codec: the HDA codec
- @nid: NID of the pin to set device entry select
- @dev_id: device entry id to be set
- Set the device entry select on the pin nid.
- */
+int snd_hda_set_dev_select(struct hda_codec *codec, hda_nid_t nid, int dev_id) +{
- int ret, dev, num_devices;
- unsigned long timeout;
- /* not support dp_mst will always return 0, using first dev_entry */
- if (!codec->dp_mst)
return 0;- /* AC_PAR_DEVLIST_LEN is 0 based. */
- num_devices = snd_hda_get_num_devices(codec, nid);
- /* If Device List Length is 0, the pin is not multi stream capable.
*/- if (num_devices == 0)
return 0;- /* Behavior of setting index being equal to or greater than
* Device List Length is not predictable*/- if (num_devices + 1 <= dev_id)
return 0;
Is this correct? Doesn't num_devices=1 mean that there is only a single device? If dev_id=1 must be invalid, but the check above passes. The standard form of such index check is like
if (dev_id >= num_devices) error;
And this also leads to the question. Shouldn't we return an error if an invalid dev_id is given?
- timeout = jiffies + msecs_to_jiffies(500);
- /* make sure the device entry selection takes effect */
- do {
ret = snd_hda_codec_write(codec, nid, 0,AC_VERB_SET_DEVICE_SEL, dev_id);udelay(20);dev = snd_hda_get_dev_select(codec, nid);if (dev == dev_id)break;msleep(20);- } while (time_before(jiffies, timeout));
Is this loop needed? Most verbs take effect immediately, and so far, the only exception is the power state.
Takashi