[PATCH 2/2] soc: qcom: rpmh-rsc: Skip read requests on unsupported platforms

[Maulik Shah]

On some platforms AOSS do not respond to read requests. Read request in
such cases will consume the ACTIVE TCS but forever waits for a response
blocking the subsequent write requests.

Skip issuing read commands on sm8150 and sc8180x platforms. For such
platforms return success to the caller with the resource level at zero
to avoid the caller taking any action on error code.

Fixes: edbafe65eef2 ("soc: qcom: rpmh: Add support to read back resource settings")
Signed-off-by: Maulik Shah <maulik.shah@xxxxxxxxxxxxxxxx>
---
 drivers/soc/qcom/rpmh-internal.h | 2 ++
 drivers/soc/qcom/rpmh-rsc.c      | 7 +++++++
 drivers/soc/qcom/rpmh.c          | 6 ++++++
 3 files changed, 15 insertions(+)

diff --git a/drivers/soc/qcom/rpmh-internal.h b/drivers/soc/qcom/rpmh-internal.h
index 39441a25af9b..960a62f0e931 100644
--- a/drivers/soc/qcom/rpmh-internal.h
+++ b/drivers/soc/qcom/rpmh-internal.h
@@ -75,12 +75,14 @@ struct rpmh_request {
  * @cache: the list of cached requests
  * @cache_lock: synchronize access to the cache data
  * @dirty: was the cache updated since flush
+ * @no_rpmh_read: controller does not support or respond to read commands
  * @batch_cache: Cache sleep and wake requests sent as batch
  */
 struct rpmh_ctrlr {
 	struct list_head cache;
 	spinlock_t cache_lock;
 	bool dirty;
+	bool no_rpmh_read;
 	struct list_head batch_cache;
 };
 
diff --git a/drivers/soc/qcom/rpmh-rsc.c b/drivers/soc/qcom/rpmh-rsc.c
index f84a399fa5dc..7a210f924af8 100644
--- a/drivers/soc/qcom/rpmh-rsc.c
+++ b/drivers/soc/qcom/rpmh-rsc.c
@@ -986,6 +986,12 @@ static void rpmh_rsc_cpu_pm_unregister(void *data)
 	cpu_pm_unregister_notifier(data);
 }
 
+static bool rpmh_rsc_no_rpmh_read(void)
+{
+	return of_machine_is_compatible("qcom,sm8150") ||
+	       of_machine_is_compatible("qcom,sc8180x");
+}
+
 static int rpmh_probe_tcs_config(struct platform_device *pdev, struct rsc_drv *drv)
 {
 	struct tcs_type_config {
@@ -1155,6 +1161,7 @@ static int rpmh_rsc_probe(struct platform_device *pdev)
 	spin_lock_init(&drv->client.cache_lock);
 	INIT_LIST_HEAD(&drv->client.cache);
 	INIT_LIST_HEAD(&drv->client.batch_cache);
+	drv->client.no_rpmh_read = rpmh_rsc_no_rpmh_read();
 
 	dev_set_drvdata(&pdev->dev, drv);
 	drv->dev = &pdev->dev;
diff --git a/drivers/soc/qcom/rpmh.c b/drivers/soc/qcom/rpmh.c
index 360242a315e3..fed2ea06f490 100644
--- a/drivers/soc/qcom/rpmh.c
+++ b/drivers/soc/qcom/rpmh.c
@@ -240,12 +240,18 @@ int rpmh_read(const struct device *dev, struct tcs_cmd *cmd)
 {
 	DECLARE_COMPLETION_ONSTACK(compl);
 	DEFINE_RPMH_MSG_ONSTACK(dev, RPMH_ACTIVE_ONLY_STATE, &compl, rpm_msg);
+	struct rpmh_ctrlr *ctrlr = get_rpmh_ctrlr(dev);
 	int ret;
 
 	ret = __fill_rpmh_msg(&rpm_msg, RPMH_ACTIVE_ONLY_STATE, cmd, 1, true);
 	if (ret)
 		return ret;
 
+	if (ctrlr->no_rpmh_read) {
+		cmd[0].data = 0;
+		return 0;
+	}
+
 	ret = __rpmh_write(dev, RPMH_ACTIVE_ONLY_STATE, &rpm_msg);
 	if (ret)
 		return ret;

-- 
2.43.0