ASoC: wm_adsp: Correct control read size when parsing compressed buffer

When parsing the compressed stream the whole buffer descriptor is
now read in a single cs_dsp_coeff_read_ctrl; on older firmwares
this descriptor is just 4 bytes but on more modern firmwares it is
24 bytes. The current code reads the full 24 bytes regardless, this
was working but reading junk for the last 20 bytes. However commit
f444da3 ("firmware: cs_dsp: Add offset to cs_dsp read/write")
added a size check into cs_dsp_coeff_read_ctrl, causing the older
firmwares to now return an error.

Update the code to only read the amount of data appropriate for
the firmware loaded.

Fixes: 04ae085 ("ASoC: wm_adsp: Switch to using wm_coeff_read_ctrl for compressed buffers")
Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Link: https://lore.kernel.org/r/20220210172053.22782-1-ckeepax@opensource.cirrus.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: charleskeepax

sound/soc/codecs/wm_adsp.c

@@ -1441,7 +1441,8 @@ static int wm_adsp_buffer_parse_coeff(struct cs_dsp_coeff_ctl *cs_ctl)
 	int ret, i;
 
 	for (i = 0; i < 5; ++i) {
-		ret = cs_dsp_coeff_read_ctrl(cs_ctl, 0, &coeff_v1, sizeof(coeff_v1));
+		ret = cs_dsp_coeff_read_ctrl(cs_ctl, 0, &coeff_v1,
+					     min(cs_ctl->len, sizeof(coeff_v1)));
 		if (ret < 0)
 			return ret;