pmdomain: qcom: rpmhpd: Skip retention level for Power Domains

In the cases where the power domain connected to logics is allowed to
transition from a level(L)-->power collapse(0)-->retention(1) or
vice versa retention(1)-->power collapse(0)-->level(L)  will cause the
logic to lose the configurations. The ARC does not support retention
to collapse transition on MxC rails.

The targets from SM8450 onwards the PLL logics of clock controllers are
connected to MxC rails and the recommended configurations are carried
out during the clock controller probes. The MxC transition as mentioned
above should be skipped to ensure the PLL settings are intact across
clock controller power on & off.

On older targets that do not split MX into MxA and MxC does not collapse
the logic and it is parked always at RETENTION, thus this issue is never
observed on those targets.

Cc: stable@vger.kernel.org # v5.17
Reviewed-by: Bjorn Andersson <andersson@kernel.org>
Signed-off-by: Taniya Das <quic_tdas@quicinc.com>
Link: https://lore.kernel.org/r/20240625-avoid_mxc_retention-v2-1-af9c2f549a5f@quicinc.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
diff --git a/drivers/pmdomain/qcom/rpmhpd.c b/drivers/pmdomain/qcom/rpmhpd.c
index de9121e..d2cb427 100644
--- a/drivers/pmdomain/qcom/rpmhpd.c
+++ b/drivers/pmdomain/qcom/rpmhpd.c
@@ -40,6 +40,7 @@
  * @addr:		Resource address as looped up using resource name from
  *			cmd-db
  * @state_synced:	Indicator that sync_state has been invoked for the rpmhpd resource
+ * @skip_retention_level: Indicate that retention level should not be used for the power domain
  */
 struct rpmhpd {
 	struct device	*dev;
@@ -56,6 +57,7 @@
 	const char	*res_name;
 	u32		addr;
 	bool		state_synced;
+	bool            skip_retention_level;
 };
 
 struct rpmhpd_desc {
@@ -173,6 +175,7 @@
 	.pd = { .name = "mxc", },
 	.peer = &mxc_ao,
 	.res_name = "mxc.lvl",
+	.skip_retention_level = true,
 };
 
 static struct rpmhpd mxc_ao = {
@@ -180,6 +183,7 @@
 	.active_only = true,
 	.peer = &mxc,
 	.res_name = "mxc.lvl",
+	.skip_retention_level = true,
 };
 
 static struct rpmhpd nsp = {
@@ -819,6 +823,9 @@
 		return -EINVAL;
 
 	for (i = 0; i < rpmhpd->level_count; i++) {
+		if (rpmhpd->skip_retention_level && buf[i] == RPMH_REGULATOR_LEVEL_RETENTION)
+			continue;
+
 		rpmhpd->level[i] = buf[i];
 
 		/* Remember the first corner with non-zero level */