interconnect: qcom: Misc bcm-voter changes and fixes

PATCH Superseded Mike Tipton 2 participants 9 messages Jul 10, 2020 – Jul 18, 2020

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Mike Tipton

author

2020-07-10 01:58 UTC #0 lore raw

v2 cover interconnect: qcom: Misc bcm-voter changes and fixes

These changes are mostly unrelated, but there are some dependencies between them.

v2:
- New patch for generic qcom,icc.h bindings
- New patch for documenting qcom,tcs-wait property
- Update bcm_div() 'base' parameter from u64 to u32

Mike Tipton (6):
dt-bindings: interconnect: Add generic qcom bindings
dt-bindings: interconnect: Add property to set BCM TCS wait behavior
interconnect: qcom: Support bcm-voter-specific TCS wait behavior
interconnect: qcom: Only wait for completion in AMC/WAKE by default
interconnect: qcom: Add support for per-BCM scaling factors
interconnect: qcom: Fix small BW votes being truncated to zero

 .../bindings/interconnect/qcom,bcm-voter.yaml | 13 ++++
 drivers/interconnect/qcom/bcm-voter.c         | 63 ++++++++++++-------
 drivers/interconnect/qcom/icc-rpmh.c          |  3 +
 drivers/interconnect/qcom/icc-rpmh.h          | 20 ++----
 include/dt-bindings/interconnect/qcom,icc.h   | 26 ++++++++
 5 files changed, 88 insertions(+), 37 deletions(-)
 create mode 100644 include/dt-bindings/interconnect/qcom,icc.h

Signature · 2 lines

The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

Mike Tipton

author

2020-07-10 01:57 UTC #1 lore raw

PATCH v2 1/6 dt-bindings: interconnect: Add generic qcom bindings

Add generic qcom interconnect bindings that are common across platforms. In particular, these include QCOM_ICC_TAG_* macros that clients can use when calling icc_set_tag().

Signed-off-by Mike Tipton <[email protected]>

---
 drivers/interconnect/qcom/icc-rpmh.h        | 18 ++------------
 include/dt-bindings/interconnect/qcom,icc.h | 26 +++++++++++++++++++++
 2 files changed, 28 insertions(+), 16 deletions(-)
 create mode 100644 include/dt-bindings/interconnect/qcom,icc.h

drivers/interconnect/qcom/icc-rpmh.h +2 ~~-16~~

index 903d25e61984..cb736b745e1a 100644
@@ -6,6 +6,8 @@
 #ifndef __DRIVERS_INTERCONNECT_QCOM_ICC_RPMH_H__
 #define __DRIVERS_INTERCONNECT_QCOM_ICC_RPMH_H__
 
+#include <dt-bindings/interconnect/qcom,icc.h>
+
 #define to_qcom_provider(_provider) \
 	container_of(_provider, struct qcom_icc_provider, provider)

@@ -44,22 +46,6 @@ struct bcm_db {
 #define MAX_BCM_PER_NODE	3
 #define MAX_VCD			10
 
-/*
- * The AMC bucket denotes constraints that are applied to hardware when
- * icc_set_bw() completes, whereas the WAKE and SLEEP constraints are applied
- * when the execution environment transitions between active and low power mode.
- */
-#define QCOM_ICC_BUCKET_AMC		0
-#define QCOM_ICC_BUCKET_WAKE		1
-#define QCOM_ICC_BUCKET_SLEEP		2
-#define QCOM_ICC_NUM_BUCKETS		3
-#define QCOM_ICC_TAG_AMC		BIT(QCOM_ICC_BUCKET_AMC)
-#define QCOM_ICC_TAG_WAKE		BIT(QCOM_ICC_BUCKET_WAKE)
-#define QCOM_ICC_TAG_SLEEP		BIT(QCOM_ICC_BUCKET_SLEEP)
-#define QCOM_ICC_TAG_ACTIVE_ONLY	(QCOM_ICC_TAG_AMC | QCOM_ICC_TAG_WAKE)
-#define QCOM_ICC_TAG_ALWAYS		(QCOM_ICC_TAG_AMC | QCOM_ICC_TAG_WAKE |\
-					 QCOM_ICC_TAG_SLEEP)
-
 /**
  * struct qcom_icc_node - Qualcomm specific interconnect nodes
  * @name: the node name used in debugfs

include/dt-bindings/interconnect/qcom,icc.h new file +26 -0

new file mode 100644
index 000000000000..cd34f36daaaa
@@ -0,0 +1,26 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (c) 2020, The Linux Foundation. All rights reserved.
+ */
+
+#ifndef __DT_BINDINGS_INTERCONNECT_QCOM_ICC_H
+#define __DT_BINDINGS_INTERCONNECT_QCOM_ICC_H
+
+/*
+ * The AMC bucket denotes constraints that are applied to hardware when
+ * icc_set_bw() completes, whereas the WAKE and SLEEP constraints are applied
+ * when the execution environment transitions between active and low power mode.
+ */
+#define QCOM_ICC_BUCKET_AMC		0
+#define QCOM_ICC_BUCKET_WAKE		1
+#define QCOM_ICC_BUCKET_SLEEP		2
+#define QCOM_ICC_NUM_BUCKETS		3
+
+#define QCOM_ICC_TAG_AMC		(1 << QCOM_ICC_BUCKET_AMC)
+#define QCOM_ICC_TAG_WAKE		(1 << QCOM_ICC_BUCKET_WAKE)
+#define QCOM_ICC_TAG_SLEEP		(1 << QCOM_ICC_BUCKET_SLEEP)
+#define QCOM_ICC_TAG_ACTIVE_ONLY	(QCOM_ICC_TAG_AMC | QCOM_ICC_TAG_WAKE)
+#define QCOM_ICC_TAG_ALWAYS		(QCOM_ICC_TAG_AMC | QCOM_ICC_TAG_WAKE |\
+					 QCOM_ICC_TAG_SLEEP)
+
+#endif

Signature · 2 lines

The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

Mike Tipton

author

2020-07-10 01:57 UTC #2 lore raw

PATCH v2 2/6 dt-bindings: interconnect: Add property to set BCM TCS wait behavior

In reply to Mike Tipton

Add "qcom,tcs-wait" property to set which TCS should wait for completion when triggering.

Signed-off-by Mike Tipton <[email protected]>

---
 .../bindings/interconnect/qcom,bcm-voter.yaml       | 13 +++++++++++++
 1 file changed, 13 insertions(+)

Documentation/devicetree/bindings/interconnect/qcom,bcm-voter.yaml +13 -0

index 5971fc1df08d..f0c3d6b01831 100644
@@ -21,6 +21,16 @@ properties:
     enum:
       - qcom,bcm-voter
 
+  qcom,tcs-wait:
+    description: |
+      Optional mask of which TCSs (Triggered Command Sets) wait for completion
+      upon triggering. In most cases, it's necessary to wait in both the AMC
+      and WAKE sets to ensure resources are available before use. If a specific
+      RSC and its use cases can ensure sufficient delay by other means, then
+      this can be overridden to reduce latencies.
+    $ref: /schemas/types.yaml#/definitions/uint32
+    default: QCOM_ICC_TAG_ACTIVE_ONLY
+
 required:
   - compatible

@@ -39,7 +49,10 @@ examples:
   # as defined in Documentation/devicetree/bindings/soc/qcom/rpmh-rsc.txt
   - |
 
+    #include <dt-bindings/interconnect/qcom,icc.h>
+
     disp_bcm_voter: bcm_voter {
         compatible = "qcom,bcm-voter";
+        qcom,tcs-wait = <QCOM_ICC_TAG_AMC>;
     };
 ...

Signature · 2 lines

The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

Rob Herring

maintainer

2020-07-10 16:31 UTC #3 lore raw

Re: [PATCH v2 2/6] dt-bindings: interconnect: Add property to set BCM TCS wait behavior

Quoted 13 lines · Mike Tipton

Add "qcom,tcs-wait" property to set which TCS should wait for completion when triggering.
Signed-off-by Mike Tipton <[email protected]>
---
 .../bindings/interconnect/qcom,bcm-voter.yaml       | 13 +++++++++++++
 1 file changed, 13 insertions(+)
Documentation/devicetree/bindings/interconnect/qcom,bcm-voter.yaml +0 -0
index 5971fc1df08d..f0c3d6b01831 100644

Documentation/devicetree/bindings/interconnect/qcom,bcm-voter.yaml properties: · line 30

Quoted 10 lines

Documentation/devicetree/bindings/interconnect/qcom,bcm-voter.yaml +7 -0

@@ -21,6 +21,16 @@ properties:
     enum:
       - qcom,bcm-voter
 
+  qcom,tcs-wait:
+    description: |
+      Optional mask of which TCSs (Triggered Command Sets) wait for completion
+      upon triggering. In most cases, it's necessary to wait in both the AMC
+      and WAKE sets to ensure resources are available before use. If a specific
+      RSC and its use cases can ensure sufficient delay by other means, then
+      this can be overridden to reduce latencies.

I have no idea what any of this means to provide any meaningful comment.

Documentation/devicetree/bindings/interconnect/qcom,bcm-voter.yaml properties: · line 32

Quoted 2 lines

Documentation/devicetree/bindings/interconnect/qcom,bcm-voter.yaml +2 -0
+    $ref: /schemas/types.yaml#/definitions/uint32
+    default: QCOM_ICC_TAG_ACTIVE_ONLY

Can't use defines here.

Quoted 19 lines

Documentation/devicetree/bindings/interconnect/qcom,bcm-voter.yaml +4 -0

+
 required:
   - compatible

@@ -39,7 +49,10 @@ examples:
   # as defined in Documentation/devicetree/bindings/soc/qcom/rpmh-rsc.txt
   - |
 
+    #include <dt-bindings/interconnect/qcom,icc.h>
+
     disp_bcm_voter: bcm_voter {
         compatible = "qcom,bcm-voter";
+        qcom,tcs-wait = <QCOM_ICC_TAG_AMC>;
     };
...

Signature · 2 lines

The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

Mike Tipton

author

2020-07-18 00:41 UTC #4 lore raw

Re: [PATCH v2 2/6] dt-bindings: interconnect: Add property to set BCM TCS wait behavior

Quoted 27 lines · Rob Herring

Quoted 13 lines · Mike Tipton
Add "qcom,tcs-wait" property to set which TCS should wait for completion when triggering.
Signed-off-by Mike Tipton <[email protected]>
---
  .../bindings/interconnect/qcom,bcm-voter.yaml       | 13 +++++++++++++
  1 file changed, 13 insertions(+)
Documentation/devicetree/bindings/interconnect/qcom,bcm-voter.yaml +0 -0
index 5971fc1df08d..f0c3d6b01831 100644
Documentation/devicetree/bindings/interconnect/qcom,bcm-voter.yaml properties: · line 30
Quoted 10 lines
Documentation/devicetree/bindings/interconnect/qcom,bcm-voter.yaml +7 -0
@@ -21,6 +21,16 @@ properties:
      enum:
        - qcom,bcm-voter
 
+  qcom,tcs-wait:
+    description: |
+      Optional mask of which TCSs (Triggered Command Sets) wait for completion
+      upon triggering. In most cases, it's necessary to wait in both the AMC
+      and WAKE sets to ensure resources are available before use. If a specific
+      RSC and its use cases can ensure sufficient delay by other means, then
+      this can be overridden to reduce latencies.
I have no idea what any of this means to provide any meaningful comment.

Quoted 4 lines

Documentation/devicetree/bindings/interconnect/qcom,bcm-voter.yaml properties: · line 32
Quoted 2 lines
Documentation/devicetree/bindings/interconnect/qcom,bcm-voter.yaml +2 -0
+    $ref: /schemas/types.yaml#/definitions/uint32
+    default: QCOM_ICC_TAG_ACTIVE_ONLY
Can't use defines here.

What's the recommended alternative? The meaning isn't obvious as a raw number (3). We expect the defines to be used in the dt files themselves (see example below). Is this just a restriction for the default documentation specifically? I could just mention the default behavior in the description I suppose, but that seems to defeat the purpose of having a separate default key.

Quoted 20 lines

Documentation/devicetree/bindings/interconnect/qcom,bcm-voter.yaml +4 -0

+
  required:
    - compatible

@@ -39,7 +49,10 @@ examples:
    # as defined in Documentation/devicetree/bindings/soc/qcom/rpmh-rsc.txt
    - |
 
+    #include <dt-bindings/interconnect/qcom,icc.h>
+
      disp_bcm_voter: bcm_voter {
          compatible = "qcom,bcm-voter";
+        qcom,tcs-wait = <QCOM_ICC_TAG_AMC>;
      };
...

Signature · 2 lines

The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

Mike Tipton

author

2020-07-10 01:58 UTC #5 lore raw

PATCH v2 3/6 interconnect: qcom: Support bcm-voter-specific TCS wait behavior

In reply to Mike Tipton

Currently, all bcm-voters set tcs_cmd::wait=true for the last VCD command in each TCS (AMC, WAKE, and SLEEP). However, some bcm-voters don't need the completion and instead need to optimize for latency. For instance, disabling wait-for-completion in the WAKE set can decrease resume latency and allow for certain operations to occur in parallel with the WAKE TCS triggering. This is only safe in very specific situations. Keep the default behavior of always waiting, but allow it to be overridden in devicetree.

Signed-off-by Mike Tipton <[email protected]>

---
 drivers/interconnect/qcom/bcm-voter.c | 32 ++++++++++++++++++---------
 1 file changed, 21 insertions(+), 11 deletions(-)

drivers/interconnect/qcom/bcm-voter.c +21 ~~-11~~

index a3d2ef1d9903..4bba3b42b648 100644
@@ -27,6 +27,7 @@ static DEFINE_MUTEX(bcm_voter_lock);
  * @commit_list: list containing bcms to be committed to hardware
  * @ws_list: list containing bcms that have different wake/sleep votes
  * @voter_node: list of bcm voters
+ * @tcs_wait: mask for which buckets require TCS completion
  */
 struct bcm_voter {
 	struct device *dev;

@@ -35,6 +36,7 @@ struct bcm_voter {
 	struct list_head commit_list;
 	struct list_head ws_list;
 	struct list_head voter_node;
+	u32 tcs_wait;
 };
 
 static int cmp_vcd(void *priv, struct list_head *a, struct list_head *b)

@@ -89,7 +91,7 @@ static void bcm_aggregate(struct qcom_icc_bcm *bcm)
 }
 
 static inline void tcs_cmd_gen(struct tcs_cmd *cmd, u64 vote_x, u64 vote_y,
-			       u32 addr, bool commit)
+			       u32 addr, bool commit, bool wait)
 {
 	bool valid = true;

@@ -114,15 +116,16 @@ static inline void tcs_cmd_gen(struct tcs_cmd *cmd, u64 vote_x, u64 vote_y,
 	 * Set the wait for completion flag on command that need to be completed
 	 * before the next command.
 	 */
-	cmd->wait = commit;
+	cmd->wait = wait;
 }
 
-static void tcs_list_gen(struct list_head *bcm_list, int bucket,
-			 struct tcs_cmd tcs_list[MAX_BCMS],
+static void tcs_list_gen(struct bcm_voter *voter, int bucket,
+			 struct tcs_cmd tcs_list[MAX_VCD],
 			 int n[MAX_VCD + 1])
 {
+	struct list_head *bcm_list = &voter->commit_list;
 	struct qcom_icc_bcm *bcm;
-	bool commit;
+	bool commit, wait;
 	size_t idx = 0, batch = 0, cur_vcd_size = 0;
 
 	memset(n, 0, sizeof(int) * (MAX_VCD + 1));

@@ -135,8 +138,11 @@ static void tcs_list_gen(struct list_head *bcm_list, int bucket,
 			commit = true;
 			cur_vcd_size = 0;
 		}
+
+		wait = commit && (voter->tcs_wait & BIT(bucket));
+
 		tcs_cmd_gen(&tcs_list[idx], bcm->vote_x[bucket],
-			    bcm->vote_y[bucket], bcm->addr, commit);
+			    bcm->vote_y[bucket], bcm->addr, commit, wait);
 		idx++;
 		n[batch]++;
 		/*

@@ -261,8 +267,7 @@ int qcom_icc_bcm_voter_commit(struct bcm_voter *voter)
 	 * Construct the command list based on a pre ordered list of BCMs
 	 * based on VCD.
 	 */
-	tcs_list_gen(&voter->commit_list, QCOM_ICC_BUCKET_AMC, cmds, commit_idx);
-
+	tcs_list_gen(voter, QCOM_ICC_BUCKET_AMC, cmds, commit_idx);
 	if (!commit_idx[0])
 		goto out;

@@ -298,7 +303,7 @@ int qcom_icc_bcm_voter_commit(struct bcm_voter *voter)
 
 	list_sort(NULL, &voter->commit_list, cmp_vcd);
 
-	tcs_list_gen(&voter->commit_list, QCOM_ICC_BUCKET_WAKE, cmds, commit_idx);
+	tcs_list_gen(voter, QCOM_ICC_BUCKET_WAKE, cmds, commit_idx);
 
 	ret = rpmh_write_batch(voter->dev, RPMH_WAKE_ONLY_STATE, cmds, commit_idx);
 	if (ret) {

@@ -306,7 +311,7 @@ int qcom_icc_bcm_voter_commit(struct bcm_voter *voter)
 		goto out;
 	}
 
-	tcs_list_gen(&voter->commit_list, QCOM_ICC_BUCKET_SLEEP, cmds, commit_idx);
+	tcs_list_gen(voter, QCOM_ICC_BUCKET_SLEEP, cmds, commit_idx);
 
 	ret = rpmh_write_batch(voter->dev, RPMH_SLEEP_STATE, cmds, commit_idx);
 	if (ret) {

@@ -325,6 +330,7 @@ EXPORT_SYMBOL_GPL(qcom_icc_bcm_voter_commit);
 
 static int qcom_icc_bcm_voter_probe(struct platform_device *pdev)
 {
+	struct device_node *np = pdev->dev.of_node;
 	struct bcm_voter *voter;
 
 	voter = devm_kzalloc(&pdev->dev, sizeof(*voter), GFP_KERNEL);

@@ -332,7 +338,11 @@ static int qcom_icc_bcm_voter_probe(struct platform_device *pdev)
 		return -ENOMEM;
 
 	voter->dev = &pdev->dev;
-	voter->np = pdev->dev.of_node;
+	voter->np = np;
+
+	if (of_property_read_u32(np, "qcom,tcs-wait", &voter->tcs_wait))
+		voter->tcs_wait = QCOM_ICC_TAG_ALWAYS;
+
 	mutex_init(&voter->lock);
 	INIT_LIST_HEAD(&voter->commit_list);
 	INIT_LIST_HEAD(&voter->ws_list);

Signature · 2 lines

The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

Mike Tipton

author

2020-07-10 01:58 UTC #6 lore raw

PATCH v2 4/6 interconnect: qcom: Only wait for completion in AMC/WAKE by default

In reply to Mike Tipton

Change the default TCS wait behavior to only wait for completion in AMC and WAKE. Waiting isn't necessary in the SLEEP TCS, since votes are only being removed in this case. Resources can be safely disabled asynchronously in parallel with the rest of the power collapse sequence. This reduces the sleep entry latency.

Signed-off-by Mike Tipton <[email protected]>

---
 drivers/interconnect/qcom/bcm-voter.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

drivers/interconnect/qcom/bcm-voter.c +1 -1

index 4bba3b42b648..d95725b9208c 100644
@@ -341,7 +341,7 @@ static int qcom_icc_bcm_voter_probe(struct platform_device *pdev)
 	voter->np = np;
 
 	if (of_property_read_u32(np, "qcom,tcs-wait", &voter->tcs_wait))
-		voter->tcs_wait = QCOM_ICC_TAG_ALWAYS;
+		voter->tcs_wait = QCOM_ICC_TAG_ACTIVE_ONLY;
 
 	mutex_init(&voter->lock);
 	INIT_LIST_HEAD(&voter->commit_list);

Signature · 2 lines

The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

Mike Tipton

author

2020-07-10 01:57 UTC #7 lore raw

PATCH v2 5/6 interconnect: qcom: Add support for per-BCM scaling factors

In reply to Mike Tipton

Currently, bcm-voter always assumes requests are made in KBps and that BCM HW always wants them in Bps, so it always scales the requests by 1000. However, certain use cases and BCMs may use different units. Thus, add support for BCM-specific scaling factors.

Signed-off-by Mike Tipton <[email protected]>

---
 drivers/interconnect/qcom/bcm-voter.c | 4 ++--
 drivers/interconnect/qcom/icc-rpmh.c  | 3 +++
 drivers/interconnect/qcom/icc-rpmh.h  | 2 ++
 3 files changed, 7 insertions(+), 2 deletions(-)

drivers/interconnect/qcom/bcm-voter.c +2 -2

index d95725b9208c..be7660b95ccc 100644
@@ -72,11 +72,11 @@ static void bcm_aggregate(struct qcom_icc_bcm *bcm)
 			agg_peak[bucket] = max(agg_peak[bucket], temp);
 		}
 
-		temp = agg_avg[bucket] * 1000ULL;
+		temp = agg_avg[bucket] * bcm->vote_scale;
 		do_div(temp, bcm->aux_data.unit);
 		bcm->vote_x[bucket] = temp;
 
-		temp = agg_peak[bucket] * 1000ULL;
+		temp = agg_peak[bucket] * bcm->vote_scale;
 		do_div(temp, bcm->aux_data.unit);
 		bcm->vote_y[bucket] = temp;
 	}

drivers/interconnect/qcom/icc-rpmh.c +3 -0

index 3ac5182c9ab2..008846c17bec 100644
@@ -136,6 +136,9 @@ int qcom_icc_bcm_init(struct qcom_icc_bcm *bcm, struct device *dev)
 	INIT_LIST_HEAD(&bcm->list);
 	INIT_LIST_HEAD(&bcm->ws_list);
 
+	if (!bcm->vote_scale)
+		bcm->vote_scale = 1000;
+
 	/* Link Qnodes to their respective BCMs */
 	for (i = 0; i < bcm->num_nodes; i++) {
 		qn = bcm->nodes[i];

drivers/interconnect/qcom/icc-rpmh.h +2 -0

index cb736b745e1a..10b1890345b1 100644
@@ -80,6 +80,7 @@ struct qcom_icc_node {
  * @addr: address offsets used when voting to RPMH
  * @vote_x: aggregated threshold values, represents sum_bw when @type is bw bcm
  * @vote_y: aggregated threshold values, represents peak_bw when @type is bw bcm
+ * @vote_scale: scaling factor for vote_x and vote_y
  * @dirty: flag used to indicate whether the bcm needs to be committed
  * @keepalive: flag used to indicate whether a keepalive is required
  * @aux_data: auxiliary data used when calculating threshold values and

@@ -95,6 +96,7 @@ struct qcom_icc_bcm {
 	u32 addr;
 	u64 vote_x[QCOM_ICC_NUM_BUCKETS];
 	u64 vote_y[QCOM_ICC_NUM_BUCKETS];
+	u64 vote_scale;
 	bool dirty;
 	bool keepalive;
 	struct bcm_db aux_data;

Signature · 2 lines

The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

Mike Tipton

author

2020-07-10 01:57 UTC #8 lore raw

PATCH v2 6/6 interconnect: qcom: Fix small BW votes being truncated to zero

In reply to Mike Tipton

Small BW votes that translate to less than a single BCM unit are currently truncated to zero. Ensure that non-zero BW requests always result in at least a vote of 1 to BCM.

Fixes 976daac4a1c5 ("interconnect: qcom: Consolidate interconnect RPMh support")

Signed-off-by Mike Tipton <[email protected]>

---
 drivers/interconnect/qcom/bcm-voter.c | 27 +++++++++++++++++++--------
 1 file changed, 19 insertions(+), 8 deletions(-)

drivers/interconnect/qcom/bcm-voter.c +19 -8

index be7660b95ccc..887d13721e52 100644
@@ -54,8 +54,20 @@ static int cmp_vcd(void *priv, struct list_head *a, struct list_head *b)
 		return 1;
 }
 
+static u64 bcm_div(u64 num, u32 base)
+{
+	/* Ensure that small votes aren't lost. */
+	if (num && num < base)
+		return 1;
+
+	do_div(num, base);
+
+	return num;
+}
+
 static void bcm_aggregate(struct qcom_icc_bcm *bcm)
 {
+	struct qcom_icc_node *node;
 	size_t i, bucket;
 	u64 agg_avg[QCOM_ICC_NUM_BUCKETS] = {0};
 	u64 agg_peak[QCOM_ICC_NUM_BUCKETS] = {0};

@@ -63,22 +75,21 @@ static void bcm_aggregate(struct qcom_icc_bcm *bcm)
 
 	for (bucket = 0; bucket < QCOM_ICC_NUM_BUCKETS; bucket++) {
 		for (i = 0; i < bcm->num_nodes; i++) {
-			temp = bcm->nodes[i]->sum_avg[bucket] * bcm->aux_data.width;
-			do_div(temp, bcm->nodes[i]->buswidth * bcm->nodes[i]->channels);
+			node = bcm->nodes[i];
+			temp = bcm_div(node->sum_avg[bucket] * bcm->aux_data.width,
+				       node->buswidth * node->channels);
 			agg_avg[bucket] = max(agg_avg[bucket], temp);
 
-			temp = bcm->nodes[i]->max_peak[bucket] * bcm->aux_data.width;
-			do_div(temp, bcm->nodes[i]->buswidth);
+			temp = bcm_div(node->max_peak[bucket] * bcm->aux_data.width,
+				       node->buswidth);
 			agg_peak[bucket] = max(agg_peak[bucket], temp);
 		}
 
 		temp = agg_avg[bucket] * bcm->vote_scale;
-		do_div(temp, bcm->aux_data.unit);
-		bcm->vote_x[bucket] = temp;
+		bcm->vote_x[bucket] = bcm_div(temp, bcm->aux_data.unit);
 
 		temp = agg_peak[bucket] * bcm->vote_scale;
-		do_div(temp, bcm->aux_data.unit);
-		bcm->vote_y[bucket] = temp;
+		bcm->vote_y[bucket] = bcm_div(temp, bcm->aux_data.unit);
 	}
 
 	if (bcm->keepalive && bcm->vote_x[QCOM_ICC_BUCKET_AMC] == 0 &&

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