[PATCH RFC 2/2] interconnect: qcom: sdm845: Own the ALC BCM to drop its boot vote

[yoxcu]

From: Michael Auer <mick@xxxxxxxx>

On the OnePlus 6 the bootloader leaves a vote on the ALC BCM
(rpmh_read() on the APPS DRV returns 0x2000000f). No driver owns this
BCM, so the vote is never removed and the SoC never reaches AOSS sleep
or CX collapse (qcom_stats aosd and cxsd stay at 0).

Add a node without consumers for the ALC BCM on mem_noc. The provider
then owns the BCM and drops the vote at sync_state.

With this change ALC reads 0 after boot and suspend reaches CX
collapse. The average current in an idle push standby test (Wi-Fi on)
was 35.6 mA, against 43.7 mA with the ALC vote kept in the sleep set.

Assisted-by: LLM
Signed-off-by: Michael Auer <mick@xxxxxxxx>
---
 drivers/interconnect/qcom/sdm845.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/drivers/interconnect/qcom/sdm845.c b/drivers/interconnect/qcom/sdm845.c
index 1c434fd12ead..2a35ed7fce49 100644
--- a/drivers/interconnect/qcom/sdm845.c
+++ b/drivers/interconnect/qcom/sdm845.c
@@ -1114,6 +1114,13 @@ static struct qcom_icc_node ebi = {
 	.buswidth = 4,
 };
 
+/* No consumers, owns the ALC BCM so sync_state drops the boot vote */
+static struct qcom_icc_node alc = {
+	.name = "alc",
+	.channels = 1,
+	.buswidth = 1,
+};
+
 static struct qcom_icc_node qhs_mdsp_ms_mpu_cfg = {
 	.name = "qhs_mdsp_ms_mpu_cfg",
 	.channels = 1,
@@ -1250,6 +1257,14 @@ static struct qcom_icc_bcm bcm_acv = {
 	.nodes = { &ebi },
 };
 
+static struct qcom_icc_bcm bcm_alc = {
+	.name = "ALC",
+	.enable_mask = BIT(0),
+	.keepalive = false,
+	.num_nodes = 1,
+	.nodes = { &alc },
+};
+
 static struct qcom_icc_bcm bcm_mc0 = {
 	.name = "MC0",
 	.keepalive = true,
@@ -1646,6 +1661,7 @@ static const struct qcom_icc_desc sdm845_gladiator_noc = {
 static struct qcom_icc_bcm * const mem_noc_bcms[] = {
 	&bcm_mc0,
 	&bcm_acv,
+	&bcm_alc,
 	&bcm_sh0,
 	&bcm_sh1,
 	&bcm_sh2,
@@ -1669,6 +1685,7 @@ static struct qcom_icc_node * const mem_noc_nodes[] = {
 	[SLAVE_SERVICE_MEM_NOC] = &srvc_memnoc,
 	[MASTER_LLCC] = &llcc_mc,
 	[SLAVE_EBI1] = &ebi,
+	[MASTER_ALC] = &alc,
 };
 
 static const struct qcom_icc_desc sdm845_mem_noc = {
-- 
2.43.0