ASoC: pcm: Do not open FEs with no BEs connected

The check is performed in prepare-step, that is dpcm_fe_dai_prepare()
but that is very late - code operates on invalid configuration from
dpcm_fe_dai_open() till it gets there. Relocate the check to the
open-step to avoid any invalid scenarios.

Reviewed-by: Amadeusz Sławiński <amadeuszx.slawinski@linux.intel.com>
Signed-off-by: Cezary Rojewski <cezary.rojewski@intel.com>
Link: https://patch.msgid.link/20250530141231.2943351-1-cezary.rojewski@intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/sound/soc/soc-pcm.c b/sound/soc/soc-pcm.c
index 43835197d1feea1f073ece824c8bbb758e437682..2c21fd528afd0fb7188f4bffadc477149aaae18b 100644 (file)
--- a/sound/soc/soc-pcm.c
+++ b/sound/soc/soc-pcm.c
@@ -2510,17 +2510,6 @@ static int dpcm_fe_dai_prepare(struct snd_pcm_substream *substream)
 
        dpcm_set_fe_update_state(fe, stream, SND_SOC_DPCM_UPDATE_FE);
 
-       /* there is no point preparing this FE if there are no BEs */
-       if (list_empty(&fe->dpcm[stream].be_clients)) {
-               /* dev_err_once() for visibility, dev_dbg() for debugging UCM profiles */
-               dev_err_once(fe->dev, "ASoC: no backend DAIs enabled for %s, possibly missing ALSA mixer-based routing or UCM profile\n",
-                            fe->dai_link->name);
-               dev_dbg(fe->dev, "ASoC: no backend DAIs enabled for %s\n",
-                       fe->dai_link->name);
-               ret = -EINVAL;
-               goto out;
-       }
-
        ret = dpcm_be_dai_prepare(fe, stream);
        if (ret < 0)
                goto out;
@@ -2776,11 +2765,23 @@ static int dpcm_fe_dai_open(struct snd_pcm_substream *fe_substream)
        /* calculate valid and active FE <-> BE dpcms */
        dpcm_add_paths(fe, stream, &list);
 
+       /* There is no point starting up this FE if there are no BEs. */
+       if (list_empty(&fe->dpcm[stream].be_clients)) {
+               /* dev_err_once() for visibility, dev_dbg() for debugging UCM profiles. */
+               dev_err_once(fe->dev, "ASoC: no backend DAIs enabled for %s, possibly missing ALSA mixer-based routing or UCM profile\n",
+                            fe->dai_link->name);
+               dev_dbg(fe->dev, "ASoC: no backend DAIs enabled for %s\n", fe->dai_link->name);
+
+               ret = -EINVAL;
+               goto put_path;
+       }
+
        ret = dpcm_fe_dai_startup(fe_substream);
        if (ret < 0)
                dpcm_fe_dai_cleanup(fe_substream);
 
        dpcm_clear_pending_state(fe, stream);
+put_path:
        dpcm_path_put(&list);
 open_end:
        snd_soc_dpcm_mutex_unlock(fe);