From: Takashi Iwai tiwai@suse.de
[ Upstream commit f785f5ee968f7045268b8be6b0abc850c4a4277c ]
When a DRM driver turns on or off the screen with the audio capability, it notifies the ELD to HD-audio HDMI codec driver via component ops. HDMI codec driver, in turn, attaches or detaches the PCM stream for the given port on the fly.
The problem is that, since the recent code change, the HDMI driver always treats the PCM stream assignment dynamically; this ended up the confusion of the PCM device appearance. e.g. when a screen goes once off and on again, it may appear on a different PCM device before the screen-off. Although the application should treat such a change, it doesn't seem working gracefully with the current pipewire (maybe PulseAudio, too).
As a workaround, this patch changes the HDMI codec driver behavior slightly to be more consistent. Now it remembers the previous PCM slot for the given port and try to assign to it. That is, if a port is re-enabled, the driver tries to use the same PCM slot that was assigned to that port previously. If it conflicts, a new slot is searched and used like before, instead.
Note that multiple monitor connections are the only typical case where the PCM slot preservation is effective. As long as only a single monitor is connected, the behavior isn't changed, and the first PCM slot is still assigned always.
Fixes: ef6f5494faf6 ("ALSA: hda/hdmi: Use only dynamic PCM device allocation") Reviewed-by: Jaroslav Kysela perex@perex.cz Link: https://bugzilla.kernel.org/show_bug.cgi?id=217259 Link: https://lore.kernel.org/r/20230331142217.19791-1-tiwai@suse.de Signed-off-by: Takashi Iwai tiwai@suse.de Signed-off-by: Sasha Levin sashal@kernel.org --- sound/pci/hda/patch_hdmi.c | 11 +++++++++++ 1 file changed, 11 insertions(+)
diff --git a/sound/pci/hda/patch_hdmi.c b/sound/pci/hda/patch_hdmi.c index 9ea633fe93393..4ffa3a59f419f 100644 --- a/sound/pci/hda/patch_hdmi.c +++ b/sound/pci/hda/patch_hdmi.c @@ -81,6 +81,7 @@ struct hdmi_spec_per_pin { struct delayed_work work; struct hdmi_pcm *pcm; /* pointer to spec->pcm_rec[n] dynamically*/ int pcm_idx; /* which pcm is attached. -1 means no pcm is attached */ + int prev_pcm_idx; /* previously assigned pcm index */ int repoll_count; bool setup; /* the stream has been set up by prepare callback */ bool silent_stream; @@ -1380,9 +1381,17 @@ static void hdmi_attach_hda_pcm(struct hdmi_spec *spec, /* pcm already be attached to the pin */ if (per_pin->pcm) return; + /* try the previously used slot at first */ + idx = per_pin->prev_pcm_idx; + if (idx >= 0) { + if (!test_bit(idx, &spec->pcm_bitmap)) + goto found; + per_pin->prev_pcm_idx = -1; /* no longer valid, clear it */ + } idx = hdmi_find_pcm_slot(spec, per_pin); if (idx == -EBUSY) return; + found: per_pin->pcm_idx = idx; per_pin->pcm = get_hdmi_pcm(spec, idx); set_bit(idx, &spec->pcm_bitmap); @@ -1398,6 +1407,7 @@ static void hdmi_detach_hda_pcm(struct hdmi_spec *spec, return; idx = per_pin->pcm_idx; per_pin->pcm_idx = -1; + per_pin->prev_pcm_idx = idx; /* remember the previous index */ per_pin->pcm = NULL; if (idx >= 0 && idx < spec->pcm_used) clear_bit(idx, &spec->pcm_bitmap); @@ -1924,6 +1934,7 @@ static int hdmi_add_pin(struct hda_codec *codec, hda_nid_t pin_nid)
per_pin->pcm = NULL; per_pin->pcm_idx = -1; + per_pin->prev_pcm_idx = -1; per_pin->pin_nid = pin_nid; per_pin->pin_nid_idx = spec->num_nids; per_pin->dev_id = i;