On Fri, 13 Nov 2015 09:56:30 +0100, libin.yang@linux.intel.com wrote:
From: Libin Yang libin.yang@linux.intel.com
Begin to support dynamic PCM assignment to pin in hdmi audio driver.
This means PCM will not be statically bound with pin. When there is a monitor connected, the corresponding pin will try to find a proper PCM to bind. When the monitor is disconnected, the corresponding pin will unbind the PCM. This helps to reduce the PCM number when there are many pins (device entries in DP MST mode) and only a few of them work at the same time.
This patch adds the pcm member in struct hdmi_spec_per_pin. When PCM is dynamically bound to the pin, the member pcm will pointer to the corresponding pcm_rec[] in hdmi_spec, which means the hda_pcm is bound to the pin.
Signed-off-by: Libin Yang libin.yang@linux.intel.com
sound/pci/hda/patch_hdmi.c | 26 +++++++++++++++++++++----- 1 file changed, 21 insertions(+), 5 deletions(-)
diff --git a/sound/pci/hda/patch_hdmi.c b/sound/pci/hda/patch_hdmi.c index f503a88..f3363b8 100644 --- a/sound/pci/hda/patch_hdmi.c +++ b/sound/pci/hda/patch_hdmi.c @@ -82,6 +82,7 @@ struct hdmi_spec_per_pin { struct mutex lock; struct delayed_work work; struct snd_kcontrol *eld_ctl;
- struct hda_pcm *pcm; /* pointer to spec->pcm_rec[n] dynamically*/ int repoll_count; bool setup; /* the stream has been set up by prepare callback */ int channels; /* current number of channels */
@@ -140,7 +141,8 @@ struct hdmi_spec { struct hdmi_ops ops;
bool dyn_pin_out;
- bool dyn_pcm_assign;
- struct mutex pcm_lock; /*
*/
- Non-generic VIA/NVIDIA specific
@@ -378,13 +380,26 @@ static int hinfo_to_pin_index(struct hda_codec *codec, struct hda_pcm_stream *hinfo) { struct hdmi_spec *spec = codec->spec;
- struct hdmi_spec_per_pin *per_pin; int pin_idx;
- for (pin_idx = 0; pin_idx < spec->num_pins; pin_idx++)
if (get_pcm_rec(spec, pin_idx)->stream == hinfo)
return pin_idx;
- if (!spec->dyn_pcm_assign) {
for (pin_idx = 0; pin_idx < spec->num_pins; pin_idx++)
if (get_pcm_rec(spec, pin_idx)->stream == hinfo)
return pin_idx;
- } else {
mutex_lock(&spec->pcm_lock);
for (pin_idx = 0; pin_idx < spec->num_pins; pin_idx++) {
per_pin = get_pin(spec, pin_idx);
if (per_pin->pcm && per_pin->pcm->stream == hinfo) {
mutex_unlock(&spec->pcm_lock);
return pin_idx;
}
}
mutex_unlock(&spec->pcm_lock);
You can assign per_pin->pcm statically at init time when dyn_pcm_assign=false. Then the same code is used in the above.
The need of spec->pcm_lock isn't clear at this moment. I guess you're trying to avoid the race of dynamic pin assignment and release. But then the code above doesn't protect anything because you return the pin_idx as an available value after the unlock. Then the pin release can happen after this point while you're accessing with the pin_idx.
So, better to consider the implementation of lock or other mechanism once when the whole picture is ready.
Takashi