[PATCH v2] interconnect: qcom: implement get_bw with rpmh_read

[PATCH v2] interconnect: qcom: implement get_bw with rpmh_read

[Neil Armstrong]

Since we can actually read back the APPS rpmh interconnect
BCM votes we can actually implement the get_bw() callback
and provide a coherent average and peak bandwidth at probe time.

The benefits of that are:
- keep disabled BCMs disabled
- avoid voting unused BCMs to INT_MAX

If the interconnects are correctly described for a platform,
all the required BCMs would be voted to the maximum bandwidth
until sync_state is reached.

Since we only get the BCM vote, we need to redistribute
the vote values to the associated nodes. The initial BCM
votes are read back at probe time in order to be ready when
the get_bw() is called when a node is added.

Tested-by: Georgi Djakov <djakov@kernel.org> #db845c
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
---
Changes in v2:
- Added tested-by
- Rebased on v7.3-rc1 now the rpmh_read() is merged
- Link to v1: https://patch.msgid.link/20251106-topic-sm8x50-icc-read-rpmh-v1-1-d03a2e5ca5f7@linaro.org
---
 drivers/interconnect/qcom/bcm-voter.c | 36 +++++++++++++++++++++
 drivers/interconnect/qcom/bcm-voter.h |  1 +
 drivers/interconnect/qcom/icc-rpmh.c  | 60 ++++++++++++++++++++++++++++++++++-
 3 files changed, 96 insertions(+), 1 deletion(-)

diff --git a/drivers/interconnect/qcom/bcm-voter.c b/drivers/interconnect/qcom/bcm-voter.c
index a2d437a05a11..9014bf20adad 100644
--- a/drivers/interconnect/qcom/bcm-voter.c
+++ b/drivers/interconnect/qcom/bcm-voter.c
@@ -261,6 +261,42 @@ void qcom_icc_bcm_voter_add(struct bcm_voter *voter, struct qcom_icc_bcm *bcm)
 }
 EXPORT_SYMBOL_GPL(qcom_icc_bcm_voter_add);
 
+/**
+ * qcom_icc_bcm_get_bw - get current bcm vote
+ * @voter: voter used to query bcm
+ * @bcm: bcm to get current vote from
+ */
+void qcom_icc_bcm_get_bw(struct bcm_voter *voter,
+			 struct qcom_icc_bcm *bcm)
+{
+	struct tcs_cmd cmd = { .addr = bcm->addr };
+	int ret, i;
+	u64 x, y;
+
+	mutex_lock(&voter->lock);
+
+	rpmh_invalidate(voter->dev);
+
+	ret = rpmh_read(voter->dev, &cmd);
+	if (ret) {
+		pr_err("Error sending AMC RPMH requests (%d)\n", ret);
+		goto out;
+	}
+
+	x = FIELD_GET(BCM_TCS_CMD_VOTE_X_MASK, cmd.data);
+	y = FIELD_GET(BCM_TCS_CMD_VOTE_Y_MASK, cmd.data);
+
+	/* For boot-up, fill the AMC vote in all buckets */
+	for (i = 0; i < QCOM_ICC_NUM_BUCKETS; i++) {
+		bcm->vote_x[i] = x;
+		bcm->vote_y[i] = y;
+	}
+
+out:
+	mutex_unlock(&voter->lock);
+}
+EXPORT_SYMBOL_GPL(qcom_icc_bcm_get_bw);
+
 /**
  * qcom_icc_bcm_voter_commit - generates and commits tcs cmds based on bcms
  * @voter: voter that needs flushing
diff --git a/drivers/interconnect/qcom/bcm-voter.h b/drivers/interconnect/qcom/bcm-voter.h
index b4d36e349f3c..fc75d457dcc7 100644
--- a/drivers/interconnect/qcom/bcm-voter.h
+++ b/drivers/interconnect/qcom/bcm-voter.h
@@ -13,6 +13,7 @@
 #include "icc-rpmh.h"
 
 struct bcm_voter *of_bcm_voter_get(struct device *dev, const char *name);
+void qcom_icc_bcm_get_bw(struct bcm_voter *voter, struct qcom_icc_bcm *bcm);
 void qcom_icc_bcm_voter_add(struct bcm_voter *voter, struct qcom_icc_bcm *bcm);
 int qcom_icc_bcm_voter_commit(struct bcm_voter *voter);
 
diff --git a/drivers/interconnect/qcom/icc-rpmh.c b/drivers/interconnect/qcom/icc-rpmh.c
index 3b445acefece..7f2b5673629b 100644
--- a/drivers/interconnect/qcom/icc-rpmh.c
+++ b/drivers/interconnect/qcom/icc-rpmh.c
@@ -136,6 +136,61 @@ int qcom_icc_set(struct icc_node *src, struct icc_node *dst)
 }
 EXPORT_SYMBOL_GPL(qcom_icc_set);
 
+static int qcom_icc_get_bw(struct icc_node *node, u32 *avg, u32 *peak)
+{
+	struct qcom_icc_node *qn = node->data;
+	u32 avg_max = 0;
+	u32 peak_max = 0;
+	u64 x, y;
+	int i;
+
+	if (!qn->num_bcms) {
+		*avg = INT_MAX;
+		*peak = INT_MAX;
+
+		return 0;
+	}
+
+	for (i = 0; i < qn->num_bcms; ++i) {
+		struct qcom_icc_bcm *bcm = qn->bcms[i];
+
+		/* Use AMC vote for boot-up */
+		x = bcm->vote_x[QCOM_ICC_BUCKET_AMC];
+		y = bcm->vote_y[QCOM_ICC_BUCKET_AMC];
+
+		/* Consider enable mask and convert to INT_MAX */
+		if (bcm->enable_mask) {
+			if (x & bcm->enable_mask)
+				avg_max = INT_MAX;
+			if (y & bcm->enable_mask)
+				peak_max = INT_MAX;
+		} else {
+			if (x) {
+				x *= bcm->aux_data.unit;
+				do_div(x, bcm->vote_scale);
+				x *= qn->buswidth * qn->channels;
+				do_div(x, bcm->aux_data.width);
+
+				avg_max = max(avg_max, x);
+			}
+
+			if (y) {
+				y *= bcm->aux_data.unit;
+				do_div(y, bcm->vote_scale);
+				y *= qn->buswidth;
+				do_div(y, bcm->aux_data.width);
+
+				peak_max = max(peak_max, y);
+			}
+		}
+	}
+
+	*avg = avg_max;
+	*peak = peak_max;
+
+	return 0;
+}
+
 /**
  * qcom_icc_bcm_init - populates bcm aux data and connect qnodes
  * @bcm: bcm to be initialized
@@ -255,6 +310,7 @@ int qcom_icc_rpmh_probe(struct platform_device *pdev)
 	provider = &qp->provider;
 	provider->dev = dev;
 	provider->set = qcom_icc_set;
+	provider->get_bw = qcom_icc_get_bw;
 	provider->pre_aggregate = qcom_icc_pre_aggregate;
 	provider->aggregate = qcom_icc_aggregate;
 	provider->xlate_extended = qcom_icc_xlate_extended;
@@ -272,8 +328,10 @@ int qcom_icc_rpmh_probe(struct platform_device *pdev)
 	if (IS_ERR(qp->voter))
 		return PTR_ERR(qp->voter);
 
-	for (i = 0; i < qp->num_bcms; i++)
+	for (i = 0; i < qp->num_bcms; i++) {
 		qcom_icc_bcm_init(qp->bcms[i], dev);
+		qcom_icc_bcm_get_bw(qp->voter, qp->bcms[i]);
+	}
 
 	for (i = 0; i < num_nodes; i++) {
 		qn = qnodes[i];

---
base-commit: cee9395acd8043be0644b25c34bfa86623f2b935
change-id: 20251106-topic-sm8x50-icc-read-rpmh-eba461a452e7

Best regards,
--  
Neil Armstrong <neil.armstrong@linaro.org>

Re: [PATCH v2] interconnect: qcom: implement get_bw with rpmh_read

[Maulik Shah]

On 08-09-2026 13:39, Neil Armstrong wrote:
> Since we can actually read back the APPS rpmh interconnect
> BCM votes we can actually implement the get_bw() callback
> and provide a coherent average and peak bandwidth at probe time.
>
> The benefits of that are:
> - keep disabled BCMs disabled
> - avoid voting unused BCMs to INT_MAX
>
> If the interconnects are correctly described for a platform,
> all the required BCMs would be voted to the maximum bandwidth
> until sync_state is reached.
>
> Since we only get the BCM vote, we need to redistribute
> the vote values to the associated nodes. The initial BCM
> votes are read back at probe time in order to be ready when
> the get_bw() is called when a node is added.
>
> Tested-by: Georgi Djakov <djakov@kernel.org> #db845c
> Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
> ---
> Changes in v2:
> - Added tested-by
> - Rebased on v7.3-rc1 now the rpmh_read() is merged
> - Link to v1: https://patch.msgid.link/20251106-topic-sm8x50-icc-read-rpmh-v1-1-d03a2e5ca5f7@linaro.org
> ---
>  drivers/interconnect/qcom/bcm-voter.c | 36 +++++++++++++++++++++
>  drivers/interconnect/qcom/bcm-voter.h |  1 +
>  drivers/interconnect/qcom/icc-rpmh.c  | 60 ++++++++++++++++++++++++++++++++++-
>  3 files changed, 96 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/interconnect/qcom/bcm-voter.c b/drivers/interconnect/qcom/bcm-voter.c
> index a2d437a05a11..9014bf20adad 100644
> --- a/drivers/interconnect/qcom/bcm-voter.c
> +++ b/drivers/interconnect/qcom/bcm-voter.c
> @@ -261,6 +261,42 @@ void qcom_icc_bcm_voter_add(struct bcm_voter *voter, struct qcom_icc_bcm *bcm)
>  }
>  EXPORT_SYMBOL_GPL(qcom_icc_bcm_voter_add);
>  
> +/**
> + * qcom_icc_bcm_get_bw - get current bcm vote
> + * @voter: voter used to query bcm
> + * @bcm: bcm to get current vote from
> + */
> +void qcom_icc_bcm_get_bw(struct bcm_voter *voter,
> +			 struct qcom_icc_bcm *bcm)
> +{
> +	struct tcs_cmd cmd = { .addr = bcm->addr };
> +	int ret, i;
> +	u64 x, y;
> +
> +	mutex_lock(&voter->lock);
> +
> +	rpmh_invalidate(voter->dev);

Don't see why rpmh_invalidate() is needed before a read request.

Thanks,
Maulik

> +
> +	ret = rpmh_read(voter->dev, &cmd);
> +	if (ret) {
> +		pr_err("Error sending AMC RPMH requests (%d)\n", ret);
> +		goto out;
> +	}
> +
>

Re: [PATCH v2] interconnect: qcom: implement get_bw with rpmh_read

[Neil Armstrong]

On 9/8/26 16:39, Maulik Shah wrote:
> 
> On 08-09-2026 13:39, Neil Armstrong wrote:
>> Since we can actually read back the APPS rpmh interconnect
>> BCM votes we can actually implement the get_bw() callback
>> and provide a coherent average and peak bandwidth at probe time.
>>
>> The benefits of that are:
>> - keep disabled BCMs disabled
>> - avoid voting unused BCMs to INT_MAX
>>
>> If the interconnects are correctly described for a platform,
>> all the required BCMs would be voted to the maximum bandwidth
>> until sync_state is reached.
>>
>> Since we only get the BCM vote, we need to redistribute
>> the vote values to the associated nodes. The initial BCM
>> votes are read back at probe time in order to be ready when
>> the get_bw() is called when a node is added.
>>
>> Tested-by: Georgi Djakov <djakov@kernel.org> #db845c
>> Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
>> ---
>> Changes in v2:
>> - Added tested-by
>> - Rebased on v7.3-rc1 now the rpmh_read() is merged
>> - Link to v1: https://patch.msgid.link/20251106-topic-sm8x50-icc-read-rpmh-v1-1-d03a2e5ca5f7@linaro.org
>> ---
>>   drivers/interconnect/qcom/bcm-voter.c | 36 +++++++++++++++++++++
>>   drivers/interconnect/qcom/bcm-voter.h |  1 +
>>   drivers/interconnect/qcom/icc-rpmh.c  | 60 ++++++++++++++++++++++++++++++++++-
>>   3 files changed, 96 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/interconnect/qcom/bcm-voter.c b/drivers/interconnect/qcom/bcm-voter.c
>> index a2d437a05a11..9014bf20adad 100644
>> --- a/drivers/interconnect/qcom/bcm-voter.c
>> +++ b/drivers/interconnect/qcom/bcm-voter.c
>> @@ -261,6 +261,42 @@ void qcom_icc_bcm_voter_add(struct bcm_voter *voter, struct qcom_icc_bcm *bcm)
>>   }
>>   EXPORT_SYMBOL_GPL(qcom_icc_bcm_voter_add);
>>   
>> +/**
>> + * qcom_icc_bcm_get_bw - get current bcm vote
>> + * @voter: voter used to query bcm
>> + * @bcm: bcm to get current vote from
>> + */
>> +void qcom_icc_bcm_get_bw(struct bcm_voter *voter,
>> +			 struct qcom_icc_bcm *bcm)
>> +{
>> +	struct tcs_cmd cmd = { .addr = bcm->addr };
>> +	int ret, i;
>> +	u64 x, y;
>> +
>> +	mutex_lock(&voter->lock);
>> +
>> +	rpmh_invalidate(voter->dev);
> 
> Don't see why rpmh_invalidate() is needed before a read request.

You're right, will drop.

Thanks,
Neil

> 
> Thanks,
> Maulik
> 
>> +
>> +	ret = rpmh_read(voter->dev, &cmd);
>> +	if (ret) {
>> +		pr_err("Error sending AMC RPMH requests (%d)\n", ret);
>> +		goto out;
>> +	}
>> +
>>

Re: [PATCH v2] interconnect: qcom: implement get_bw with rpmh_read

[kernel test robot]

Hi Neil,

kernel test robot noticed the following build warnings:

[auto build test WARNING on cee9395acd8043be0644b25c34bfa86623f2b935]

url:    https://github.com/intel-lab-lkp/linux/commits/Neil-Armstrong/interconnect-qcom-implement-get_bw-with-rpmh_read/20260908-100915
base:   cee9395acd8043be0644b25c34bfa86623f2b935
patch link:    https://lore.kernel.org/r/20260908-topic-sm8x50-icc-read-rpmh-v2-1-b6f1c4205450%40linaro.org
patch subject: [PATCH v2] interconnect: qcom: implement get_bw with rpmh_read
config: arc-randconfig-r112-20260909 (https://download.01.org/0day-ci/archive/20260909/202609091547.IZVghFTg-lkp@intel.com/config)
compiler: arc-linux-gcc (GCC) 10.5.0
sparse: v0.6.5-rc1
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260909/202609091547.IZVghFTg-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202609091547.IZVghFTg-lkp@intel.com/

sparse warnings: (new ones prefixed by >>)
>> drivers/interconnect/qcom/icc-rpmh.c:169:35: sparse: sparse: invalid assignment: *=
   drivers/interconnect/qcom/icc-rpmh.c:169:35: sparse:    left side has type unsigned long long
   drivers/interconnect/qcom/icc-rpmh.c:169:35: sparse:    right side has type restricted __le32
>> drivers/interconnect/qcom/icc-rpmh.c:172:33: sparse: sparse: incorrect type in initializer (different base types) @@     expected unsigned int [usertype] __base @@     got restricted __le16 [usertype] width @@
   drivers/interconnect/qcom/icc-rpmh.c:172:33: sparse:     expected unsigned int [usertype] __base
   drivers/interconnect/qcom/icc-rpmh.c:172:33: sparse:     got restricted __le16 [usertype] width
   drivers/interconnect/qcom/icc-rpmh.c:178:35: sparse: sparse: invalid assignment: *=
   drivers/interconnect/qcom/icc-rpmh.c:178:35: sparse:    left side has type unsigned long long
   drivers/interconnect/qcom/icc-rpmh.c:178:35: sparse:    right side has type restricted __le32
   drivers/interconnect/qcom/icc-rpmh.c:181:33: sparse: sparse: incorrect type in initializer (different base types) @@     expected unsigned int [usertype] __base @@     got restricted __le16 [usertype] width @@
   drivers/interconnect/qcom/icc-rpmh.c:181:33: sparse:     expected unsigned int [usertype] __base
   drivers/interconnect/qcom/icc-rpmh.c:181:33: sparse:     got restricted __le16 [usertype] width
   drivers/interconnect/qcom/icc-rpmh.c:231:28: sparse: sparse: incorrect type in assignment (different base types) @@     expected restricted __le32 [usertype] unit @@     got unsigned int [usertype] @@
   drivers/interconnect/qcom/icc-rpmh.c:231:28: sparse:     expected restricted __le32 [usertype] unit
   drivers/interconnect/qcom/icc-rpmh.c:231:28: sparse:     got unsigned int [usertype]
   drivers/interconnect/qcom/icc-rpmh.c:232:29: sparse: sparse: incorrect type in assignment (different base types) @@     expected restricted __le16 [usertype] width @@     got unsigned short [usertype] @@
   drivers/interconnect/qcom/icc-rpmh.c:232:29: sparse:     expected restricted __le16 [usertype] width
   drivers/interconnect/qcom/icc-rpmh.c:232:29: sparse:     got unsigned short [usertype]

vim +169 drivers/interconnect/qcom/icc-rpmh.c

   138	
   139	static int qcom_icc_get_bw(struct icc_node *node, u32 *avg, u32 *peak)
   140	{
   141		struct qcom_icc_node *qn = node->data;
   142		u32 avg_max = 0;
   143		u32 peak_max = 0;
   144		u64 x, y;
   145		int i;
   146	
   147		if (!qn->num_bcms) {
   148			*avg = INT_MAX;
   149			*peak = INT_MAX;
   150	
   151			return 0;
   152		}
   153	
   154		for (i = 0; i < qn->num_bcms; ++i) {
   155			struct qcom_icc_bcm *bcm = qn->bcms[i];
   156	
   157			/* Use AMC vote for boot-up */
   158			x = bcm->vote_x[QCOM_ICC_BUCKET_AMC];
   159			y = bcm->vote_y[QCOM_ICC_BUCKET_AMC];
   160	
   161			/* Consider enable mask and convert to INT_MAX */
   162			if (bcm->enable_mask) {
   163				if (x & bcm->enable_mask)
   164					avg_max = INT_MAX;
   165				if (y & bcm->enable_mask)
   166					peak_max = INT_MAX;
   167			} else {
   168				if (x) {
 > 169					x *= bcm->aux_data.unit;
   170					do_div(x, bcm->vote_scale);
   171					x *= qn->buswidth * qn->channels;
 > 172					do_div(x, bcm->aux_data.width);
   173	
   174					avg_max = max(avg_max, x);
   175				}
   176	
   177				if (y) {
   178					y *= bcm->aux_data.unit;
   179					do_div(y, bcm->vote_scale);
   180					y *= qn->buswidth;
   181					do_div(y, bcm->aux_data.width);
   182	
   183					peak_max = max(peak_max, y);
   184				}
   185			}
   186		}
   187	
   188		*avg = avg_max;
   189		*peak = peak_max;
   190	
   191		return 0;
   192	}
   193	

--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki