ASoC: soc-core: disable route checks for legacy devices

v5.4 changes in soc-core tightened the checks on soc_dapm_add_routes,
which results in the ASoC card probe failing.

Introduce a flag to be set in machine drivers to prevent the probe
from stopping in case of incomplete topologies or missing routes. This
flag is for backwards compatibility only and shall not be used for
newer machine drivers.

Example with an HDaudio card with a bad topology:

[ 236.177898] skl_hda_dsp_generic skl_hda_dsp_generic: ASoC: Failed to
add route iDisp1_out -> direct -> iDisp1 Tx

[ 236.177902] skl_hda_dsp_generic skl_hda_dsp_generic:
snd_soc_bind_card: snd_soc_dapm_add_routes failed: -19

with the disable_route_checks set:

[ 64.031657] skl_hda_dsp_generic skl_hda_dsp_generic: ASoC: Failed to
add route iDisp1_out -> direct -> iDisp1 Tx

[ 64.031661] skl_hda_dsp_generic skl_hda_dsp_generic:
snd_soc_bind_card: disable_route_checks set, ignoring errors on
add_routes

Fixes: daa480bd ("ASoC: soc-core: tidyup for snd_soc_dapm_add_routes()")
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Acked-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Link: https://lore.kernel.org/r/20200309192744.18380-2-pierre-louis.bossart@linux.intel.comSigned-off-by: Mark Brown <broonie@kernel.org>

include/sound/soc.h

@@ -1058,6 +1058,7 @@ struct snd_soc_card {
 	const struct snd_soc_dapm_route *of_dapm_routes;
 	int num_of_dapm_routes;
 	bool fully_routed;
+	bool disable_route_checks;
 
 	/* lists of probed devices belonging to this card */
 	struct list_head component_dev_list;

sound/soc/soc-core.c

@@ -1256,8 +1256,18 @@ static int soc_probe_component(struct snd_soc_card *card,
 	ret = snd_soc_dapm_add_routes(dapm,
 				      component->driver->dapm_routes,
 				      component->driver->num_dapm_routes);
-	if (ret < 0)
-		goto err_probe;
+	if (ret < 0) {
+		if (card->disable_route_checks) {
+			dev_info(card->dev,
+				 "%s: disable_route_checks set, ignoring errors on add_routes\n",
+				 __func__);
+		} else {
+			dev_err(card->dev,
+				"%s: snd_soc_dapm_add_routes failed: %d\n",
+				__func__, ret);
+			goto err_probe;
+		}
+	}
 
 	/* see for_each_card_components */
 	list_add(&component->card_list, &card->component_dev_list);
@@ -1938,8 +1948,18 @@ static int snd_soc_bind_card(struct snd_soc_card *card)
 
 	ret = snd_soc_dapm_add_routes(&card->dapm, card->dapm_routes,
 				      card->num_dapm_routes);
-	if (ret < 0)
-		goto probe_end;
+	if (ret < 0) {
+		if (card->disable_route_checks) {
+			dev_info(card->dev,
+				 "%s: disable_route_checks set, ignoring errors on add_routes\n",
+				 __func__);
+		} else {
+			dev_err(card->dev,
+				 "%s: snd_soc_dapm_add_routes failed: %d\n",
+				 __func__, ret);
+			goto probe_end;
+		}
+	}
 
 	ret = snd_soc_dapm_add_routes(&card->dapm, card->of_dapm_routes,
 				      card->num_of_dapm_routes);