ASoC: wm_adsp: Report when a control write changes the value

Merge series from Richard Fitzgerald <rf@opensource.cirrus.com>:

Writing a firmware control should be returning 1 if the control value
changed, so these two patches add that.

Though this is an ALSA requirement it is also useful for non-ALSA clients
of cs_dsp to know if the control value changed, so the main handling is
implemented in cs_dsp. TLV controls are specifically an ALSA thing so they
are handled specially in wm_adsp.

Simon Trimmer (2):
  firmware: cs_dsp: cs_dsp_coeff_write_ctrl() should report changed
  ASoC: wm_adsp: Return whether changed when writing controls

 drivers/firmware/cirrus/cs_dsp.c | 17 ++++++++++++-----
 sound/soc/codecs/wm_adsp.c       | 27 ++++++++++++++++++---------
 2 files changed, 30 insertions(+), 14 deletions(-)

--
2.30.2

1 files changed, 12 insertions, 5 deletions

diff --git a/drivers/firmware/cirrus/cs_dsp.c b/drivers/firmware/cirrus/cs_dsp.c
index 81cc3d0f6eec..17b7198b87dc 100644
--- a/drivers/firmware/cirrus/cs_dsp.c
+++ b/drivers/firmware/cirrus/cs_dsp.c
@@ -752,7 +752,7 @@ static int cs_dsp_coeff_write_ctrl_raw(struct cs_dsp_coeff_ctl *ctl,
  *
  * Must be called with pwr_lock held.
  *
- * Return: Zero for success, a negative number on error.
+ * Return: < 0 on error, 1 when the control value changed and 0 when it has not.
  */
 int cs_dsp_coeff_write_ctrl(struct cs_dsp_coeff_ctl *ctl,
 			    unsigned int off, const void *buf, size_t len)
@@ -767,16 +767,23 @@ int cs_dsp_coeff_write_ctrl(struct cs_dsp_coeff_ctl *ctl,
 	if (len + off * sizeof(u32) > ctl->len)
 		return -EINVAL;
 
-	if (ctl->flags & WMFW_CTL_FLAG_VOLATILE)
+	if (ctl->flags & WMFW_CTL_FLAG_VOLATILE) {
 		ret = -EPERM;
-	else if (buf != ctl->cache)
-		memcpy(ctl->cache + off * sizeof(u32), buf, len);
+	} else if (buf != ctl->cache) {
+		if (memcmp(ctl->cache + off * sizeof(u32), buf, len))
+			memcpy(ctl->cache + off * sizeof(u32), buf, len);
+		else
+			return 0;
+	}
 
 	ctl->set = 1;
 	if (ctl->enabled && ctl->dsp->running)
 		ret = cs_dsp_coeff_write_ctrl_raw(ctl, off, buf, len);
 
-	return ret;
+	if (ret < 0)
+		return ret;
+
+	return 1;
 }
 EXPORT_SYMBOL_GPL(cs_dsp_coeff_write_ctrl);