soc: qcom: rpmhpd: Use highest corner until sync_state

In some cases the hardware that the bootloader has left configured
depends on RPMH power domains for their operation up until the point
where the related Linux device driver probes and can inherit that
configuration, or power down the hardware gracefully.

Unfortunately as Linux probes the releavant drivers in sequence there
are periods during the Linux boot flow where either the genpd refcount
will reach 0, or worse where the active performance_state votes does not
meet the requirements of the state that the hardware was left in.

One specific example of this is during boot of e.g. SM8150/SC8180X,
where the display clock controller probes, without any particular
performance state needs (to access its registers). This will drop the
MMCX rail to MIN_SVS, which isn't sufficient to sustain the clock rates
that the later probing MDP is configured to. This results in an
unrecoverable system state.

Handle both these cases by keeping the RPMH power-domais that are
referenced voted for highest state, until sync_state indicates that all
devices referencing the RPMH power-domain driver has been probed.
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Reviewed-by: Caleb Connolly <caleb@connolly.tech>
Reviewed-by: Konrad Dybcio <konrad.dybcio@somainline.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
[bjorn: Added print for sync_state errors]
Signed-off-by: Bjorn Andersson <quic_bjorande@quicinc.com>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20220915205559.14574-1-quic_bjorande@quicinc.com

drivers/soc/qcom/rpmhpd.c

@@ -39,6 +39,7 @@
  * @res_name:		Resource name used for cmd-db lookup
  * @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
  */
 struct rpmhpd {
 	struct device	*dev;
@@ -54,6 +55,7 @@ struct rpmhpd {
 	bool		enabled;
 	const char	*res_name;
 	u32		addr;
+	bool		state_synced;
 };
 
 struct rpmhpd_desc {
@@ -511,7 +513,13 @@ static int rpmhpd_aggregate_corner(struct rpmhpd *pd, unsigned int corner)
 	unsigned int this_active_corner = 0, this_sleep_corner = 0;
 	unsigned int peer_active_corner = 0, peer_sleep_corner = 0;
 
-	to_active_sleep(pd, corner, &this_active_corner, &this_sleep_corner);
+	if (pd->state_synced) {
+		to_active_sleep(pd, corner, &this_active_corner, &this_sleep_corner);
+	} else {
+		/* Clamp to highest corner if sync_state hasn't happened */
+		this_active_corner = pd->level_count - 1;
+		this_sleep_corner = pd->level_count - 1;
+	}
 
 	if (peer && peer->enabled)
 		to_active_sleep(peer, peer->corner, &peer_active_corner,
@@ -726,11 +734,40 @@ static int rpmhpd_probe(struct platform_device *pdev)
 	return of_genpd_add_provider_onecell(pdev->dev.of_node, data);
 }
 
+static void rpmhpd_sync_state(struct device *dev)
+{
+	const struct rpmhpd_desc *desc = of_device_get_match_data(dev);
+	struct rpmhpd **rpmhpds = desc->rpmhpds;
+	unsigned int corner;
+	struct rpmhpd *pd;
+	unsigned int i;
+	int ret;
+
+	mutex_lock(&rpmhpd_lock);
+	for (i = 0; i < desc->num_pds; i++) {
+		pd = rpmhpds[i];
+		if (!pd)
+			continue;
+
+		pd->state_synced = true;
+		if (pd->enabled)
+			corner = max(pd->corner, pd->enable_corner);
+		else
+			corner = 0;
+
+		ret = rpmhpd_aggregate_corner(pd, corner);
+		if (ret)
+			dev_err(dev, "failed to sync %s\n", pd->res_name);
+	}
+	mutex_unlock(&rpmhpd_lock);
+}
+
 static struct platform_driver rpmhpd_driver = {
 	.driver = {
 		.name = "qcom-rpmhpd",
 		.of_match_table = rpmhpd_match_table,
 		.suppress_bind_attrs = true,
+		.sync_state = rpmhpd_sync_state,
 	},
 	.probe = rpmhpd_probe,
 };