[PATCH v1] ASoC: cs35l41: Fallback to using HID for system_name if no SUB is available

[Stefan Binding <sbinding@opensource.cirrus.com>]

For systems which load firmware on the cs35l41 which use ACPI, the
_SUB value is used to differentiate firmware and tuning files for the
individual systems. In the case where a system does not have a _SUB
defined in ACPI node for cs35l41, there needs to be a fallback to
allow the files for that system to be differentiated. Since all
ACPI nodes for cs35l41 should have a HID defined, the HID should be a
safe option.

Signed-off-by: Stefan Binding <sbinding@opensource.cirrus.com>
---
 sound/soc/codecs/cs35l41.c | 23 ++++++++++++++++-------
 1 file changed, 16 insertions(+), 7 deletions(-)

diff --git a/sound/soc/codecs/cs35l41.c b/sound/soc/codecs/cs35l41.c
index 07a5cab35fe1..30b89018b113 100644
--- a/sound/soc/codecs/cs35l41.c
+++ b/sound/soc/codecs/cs35l41.c
@@ -1150,19 +1150,28 @@ static int cs35l41_dsp_init(struct cs35l41_private *cs35l41)
 
 static int cs35l41_acpi_get_name(struct cs35l41_private *cs35l41)
 {
-	acpi_handle handle = ACPI_HANDLE(cs35l41->dev);
+	struct acpi_device *adev = ACPI_COMPANION(cs35l41->dev);
+	acpi_handle handle = acpi_device_handle(adev);
+	const char *hid;
 	const char *sub;
 
-	/* If there is no ACPI_HANDLE, there is no ACPI for this system, return 0 */
-	if (!handle)
+	/* If there is no acpi_device, there is no ACPI for this system, return 0 */
+	if (!adev)
 		return 0;
 
 	sub = acpi_get_subsystem_id(handle);
 	if (IS_ERR(sub)) {
-		/* If bad ACPI, return 0 and fallback to legacy firmware path, otherwise fail */
-		if (PTR_ERR(sub) == -ENODATA)
-			return 0;
-		else
+		/* If no _SUB, fallback to _HID, otherwise fail */
+		if (PTR_ERR(sub) == -ENODATA) {
+			hid = acpi_device_hid(adev);
+			/* If dummy hid, return 0 and fallback to legacy firmware path */
+			if (!strcmp(hid, "device"))
+				return 0;
+			sub = kstrdup(hid, GFP_KERNEL);
+			if (!sub)
+				sub = ERR_PTR(-ENOMEM);
+
+		} else
 			return PTR_ERR(sub);
 	}
 
-- 
2.43.0