ASoC: cs-amp-lib: Ignore empty UEFI calibration entries

If the timestamp of a calibration entry is 0 it is an unused entry and
must be ignored.

Some end-products reserve EFI space for calibration entries by shipping
with a zero-filled EFI file. When searching the file for calibration
data the driver must skip the empty entries. The timestamp of a valid
entry is always non-zero.

Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Fixes: 1cad872 ("ASoC: cs-amp-lib: Add helpers for factory calibration data")
Link: https://patch.msgid.link/20240822133544.304421-1-rf@opensource.cirrus.com
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/codecs/cs-amp-lib.c

@@ -182,6 +182,10 @@ static int _cs_amp_get_efi_calibration_data(struct device *dev, u64 target_uid,
 		for (i = 0; i < efi_data->count; ++i) {
 			u64 cal_target = cs_amp_cal_target_u64(&efi_data->data[i]);
 
+			/* Skip empty entries */
+			if (!efi_data->data[i].calTime[0] && !efi_data->data[i].calTime[1])
+				continue;
+
 			/* Skip entries with unpopulated silicon ID */
 			if (cal_target == 0)
 				continue;
@@ -193,7 +197,8 @@ static int _cs_amp_get_efi_calibration_data(struct device *dev, u64 target_uid,
 		}
 	}
 
-	if (!cal && (amp_index >= 0) && (amp_index < efi_data->count)) {
+	if (!cal && (amp_index >= 0) && (amp_index < efi_data->count) &&
+	    (efi_data->data[amp_index].calTime[0] || efi_data->data[amp_index].calTime[1])) {
 		u64 cal_target = cs_amp_cal_target_u64(&efi_data->data[amp_index]);
 
 		/*