Re: [PATCH v2 3/5] OPP: Add support for parsing the interconnect bandwidth

From: Sibi Sankar
Date: Thu Jun 27 2019 - 02:27:44 EST

Hey Georgi,

In addition to Viresh's comments I found a few more while testing the
series on SDM845.

On 4/24/19 11:22 AM, Viresh Kumar wrote:
On 23-04-19, 16:28, Georgi Djakov wrote:
The OPP bindings now support bandwidth values, so add support to parse it
from device tree and store it into the new dev_pm_opp_icc_bw struct, which
is part of the dev_pm_opp.

Also add and export the dev_pm_opp_set_paths() and dev_pm_opp_put_paths()
helpers, to set (and release) an interconnect paths to a device. The
bandwidth of these paths will be updated when the OPPs are switched.

Signed-off-by: Georgi Djakov <georgi.djakov@xxxxxxxxxx>
---
drivers/opp/core.c | 87 ++++++++++++++++++++++++++++++++++-
drivers/opp/of.c | 102 +++++++++++++++++++++++++++++++++++++++++
drivers/opp/opp.h | 9 ++++
include/linux/pm_opp.h | 14 ++++++
4 files changed, 210 insertions(+), 2 deletions(-)

diff --git a/drivers/opp/core.c b/drivers/opp/core.c
index 0420f7e8ad5b..97ee39ecdebd 100644
--- a/drivers/opp/core.c
+++ b/drivers/opp/core.c
@@ -19,6 +19,7 @@
#include <linux/slab.h>
#include <linux/device.h>
#include <linux/export.h>
+#include <linux/interconnect.h>

Just include this once in opp.h and the other .c files won't need it.

#include <linux/pm_domain.h>
#include <linux/regulator/consumer.h>
@@ -876,6 +877,8 @@ static struct opp_table *_allocate_opp_table(struct device *dev, int index)
ret);
}
+ _of_find_paths(opp_table, dev);
+
BLOCKING_INIT_NOTIFIER_HEAD(&opp_table->head);
INIT_LIST_HEAD(&opp_table->opp_list);
kref_init(&opp_table->kref);
@@ -1129,11 +1132,12 @@ EXPORT_SYMBOL_GPL(dev_pm_opp_remove_all_dynamic);
struct dev_pm_opp *_opp_allocate(struct opp_table *table)
{
struct dev_pm_opp *opp;
- int count, supply_size;
+ int count, supply_size, icc_size;
/* Allocate space for at least one supply */
count = table->regulator_count > 0 ? table->regulator_count : 1;
supply_size = sizeof(*opp->supplies) * count;
+ icc_size = sizeof(*opp->bandwidth) * table->path_count;
/* allocate new OPP node and supplies structures */
opp = kzalloc(sizeof(*opp) + supply_size, GFP_KERNEL);

You never updated this to include icc_size :(

@@ -1141,7 +1145,8 @@ struct dev_pm_opp *_opp_allocate(struct opp_table *table)
return NULL;
/* Put the supplies at the end of the OPP structure as an empty array */
- opp->supplies = (struct dev_pm_opp_supply *)(opp + 1);
+ opp->bandwidth = (struct dev_pm_opp_icc_bw *)(opp + 1);

Keep the order as supplies and then bandwidth.

+ opp->supplies = (struct dev_pm_opp_supply *)(opp + icc_size + 1);

opp->supplies = (struct dev_pm_opp_supply *)(opp + 1);
opp->bandwidth = (struct dev_pm_opp_icc_bw *)(opp->supplies + 1);


Did you check what address gets assigned here ? I think the pointer
addition will screw things up for you.

INIT_LIST_HEAD(&opp->node);
return opp;
@@ -1637,6 +1642,84 @@ void dev_pm_opp_put_clkname(struct opp_table *opp_table)
}
EXPORT_SYMBOL_GPL(dev_pm_opp_put_clkname);
+/**
+ * dev_pm_opp_set_paths() - Set interconnect path for a device
+ * @dev: Device for which interconnect path is being set.
+ *
+ * This must be called before any OPPs are initialized for the device.
+ */
+struct opp_table *dev_pm_opp_set_paths(struct device *dev)

I got a bit confused. Why is this routine required exactly as
_of_find_paths() would have already done something similar ?

+{
+ struct opp_table *opp_table;
+ int ret, i;
+
+ opp_table = dev_pm_opp_get_opp_table(dev);
+ if (!opp_table)
+ return ERR_PTR(-ENOMEM);
+
+ /* This should be called before OPPs are initialized */
+ if (WARN_ON(!list_empty(&opp_table->opp_list))) {
+ ret = -EBUSY;
+ goto err;
+ }
+
+ /* Another CPU that shares the OPP table has set the path */
+ if (opp_table->paths)
+ return opp_table;
+ >> + opp_table->paths = kmalloc_array(opp_table->path_count,

of_find_paths might have failed so you would want to
re-calculate opp_table->path_count.

+ sizeof(*opp_table->paths), GFP_KERNEL);
+
+ /* Find interconnect path(s) for the device */
+ for (i = 0; i < opp_table->path_count; i++) {
+ opp_table->paths[i] = of_icc_get_by_index(dev, i);
+ if (IS_ERR(opp_table->paths[i])) {
+ ret = PTR_ERR(opp_table->paths[i]);
+ if (ret != -EPROBE_DEFER)
+ dev_err(dev, "%s: Couldn't find path%d: %d\n",
+ __func__, i, ret);

we should clean up by call icc_put on the paths that succeeded
and free/set the opp_table->paths to NULL.

+ goto err;
+ }
+ }
+
+ return opp_table;
+
+err:
+ dev_pm_opp_put_opp_table(opp_table);
+
+ return ERR_PTR(ret);
+}
+EXPORT_SYMBOL_GPL(dev_pm_opp_set_paths);
+
+/**
+ * dev_pm_opp_put_paths() - Release interconnect path resources
+ * @opp_table: OPP table returned from dev_pm_opp_set_paths().
+ */
+void dev_pm_opp_put_paths(struct opp_table *opp_table)
+{
+ int i;
+
+ if (!opp_table->paths) {
+ pr_err("%s: Doesn't have paths set\n", __func__);
+ return;
+ }
+
+ /* Make sure there are no concurrent readers while updating opp_table */
+ WARN_ON(!list_empty(&opp_table->opp_list));
+
+ for (i = opp_table->path_count - 1; i >= 0; i--)
+ icc_put(opp_table->paths[i]);
+
+ _free_set_opp_data(opp_table);
+
+ kfree(opp_table->paths);
+ opp_table->paths = NULL;
+ opp_table->path_count = 0;
+
+ dev_pm_opp_put_opp_table(opp_table);
+}
+EXPORT_SYMBOL_GPL(dev_pm_opp_put_paths);
+
/**
* dev_pm_opp_register_set_opp_helper() - Register custom set OPP helper
* @dev: Device for which the helper is getting registered.
diff --git a/drivers/opp/of.c b/drivers/opp/of.c
index c10c782d15aa..00af23280bc6 100644
--- a/drivers/opp/of.c
+++ b/drivers/opp/of.c
@@ -16,6 +16,7 @@
#include <linux/cpu.h>
#include <linux/errno.h>
#include <linux/device.h>
+#include <linux/interconnect.h>
#include <linux/of_device.h>
#include <linux/pm_domain.h>
#include <linux/slab.h>
@@ -363,6 +364,45 @@ static int _of_opp_alloc_required_opps(struct opp_table *opp_table,
return ret;
}
+int _of_find_paths(struct opp_table *opp_table, struct device *dev)
+{
+ struct device_node *np;
+ int ret, i, count, num_paths;
+
+ np = of_node_get(dev->of_node);
+ if (np) {

I would rather do:

if (!np)
return 0;

That will kill unnecessary line breaks and indentation.

+ count = of_count_phandle_with_args(np, "interconnects",
+ "#interconnect-cells");

count will be an error code if interconnect property is missing
so we need to account for that as well.


You can do of_node_put() right here as it isn't used afterwards.

+ if (count % 2) {

Shouldn't this be 4 instead of 2 ? Each path is represented as:

<&noc MASTER_CPU &noc SLAVE_DDR>

which has 4 fields.

+ dev_err(dev, "%s: Invalid interconnects values\n",
+ __func__);
+ ret = -EINVAL;
+ goto put_of_node;
+ }
+
+ num_paths = count / 2;
+ opp_table->paths = kcalloc(num_paths, sizeof(*opp_table->paths),
+ GFP_KERNEL);
+ if (!opp_table->paths) {
+ ret = -ENOMEM;
+ goto put_of_node;
+ }
+
+ for (i = 0; i < num_paths; i++)
+ opp_table->paths[i] = of_icc_get_by_index(dev, i);

we should clean up by call icc_put on the paths that succeeded
and free/set the opp_table->paths to NULL.

+
+ opp_table->path_count = num_paths;
+ of_node_put(np);
+ }
+
+ return 0;
+
+put_of_node:
+ of_node_put(np);
+
+ return ret;
+}
+
static bool _opp_is_supported(struct device *dev, struct opp_table *opp_table,
struct device_node *np)
{
@@ -539,6 +579,64 @@ static int opp_parse_supplies(struct dev_pm_opp *opp, struct device *dev,
return ret;
}
+static int opp_parse_icc_bw(struct dev_pm_opp *opp, struct device *dev,
+ struct opp_table *opp_table)
+{
+ struct property *prop = NULL;
+ u32 *bandwidth;
+ char name[] = "bandwidth-MBps";
+ int count, i, j, ret;
+
+ /* Search for "bandwidth-MBps" */
+ prop = of_find_property(opp->np, name, NULL);
+
+ /* Missing property is not a problem */
+ if (!prop) {
+ dev_dbg(dev, "%s: Missing %s property\n", __func__, name);
+ return 0;
+ }
+
+ if (!prop->value) {
+ dev_dbg(dev, "%s: Missing %s value\n", __func__, name);
+ return -ENODATA;
+ }
+
+ /*
+ * Bandwidth consists of average and peak values like:
+ * bandwidth-MBps = <avg-MBps peak-MBps>
+ */
+ count = prop->length / sizeof(u32);
+ if (count % 2) {
+ dev_err(dev, "%s: Invalid %s values\n", __func__, name);
+ return -EINVAL;
+ }
+
+ if (opp_table->path_count != count / 2) {
+ dev_err(dev, "%s Mismatch between values and paths (%d %d)\n",
+ __func__, opp_table->path_count, count / 2);
+ return -EINVAL;
+ }
+
+ bandwidth = kmalloc_array(count, sizeof(*bandwidth), GFP_KERNEL);
+ if (!bandwidth)
+ return -ENOMEM;
+
+ ret = of_property_read_u32_array(opp->np, name, bandwidth, count);
+ if (ret) {
+ dev_err(dev, "%s: Error parsing %s: %d\n", __func__, name, ret);
+ goto free_bandwidth;
+ }
+ for (i = 0, j = 0; i < count; i++) {
+ opp->bandwidth[i].avg = MBps_to_icc(bandwidth[j++]);
+ opp->bandwidth[i].peak = MBps_to_icc(bandwidth[j++]);
+ }
+
+free_bandwidth:
+ kfree(bandwidth);
+
+ return ret;
+}
+
/**
* dev_pm_opp_of_remove_table() - Free OPP table entries created from static DT
* entries
@@ -635,6 +733,10 @@ static struct dev_pm_opp *_opp_add_static_v2(struct opp_table *opp_table,
if (opp_table->is_genpd)
new_opp->pstate = pm_genpd_opp_to_performance_state(dev, new_opp);
+ ret = opp_parse_icc_bw(new_opp, dev, opp_table);
+ if (ret)
+ goto free_opp;
+
ret = _opp_add(dev, new_opp, opp_table, rate_not_available);
if (ret) {
/* Don't return error for duplicate OPPs */
diff --git a/drivers/opp/opp.h b/drivers/opp/opp.h
index 569b3525aa67..70a537f2dbd3 100644
--- a/drivers/opp/opp.h
+++ b/drivers/opp/opp.h
@@ -24,6 +24,7 @@
struct clk;
struct regulator;
+struct icc_path;
/* Lock to allow exclusive modification to the device and opp lists */
extern struct mutex opp_table_lock;
@@ -62,6 +63,7 @@ extern struct list_head opp_tables;
* @rate: Frequency in hertz
* @level: Performance level
* @supplies: Power supplies voltage/current values
+ * @bandwidth: Interconnect bandwidth values
* @clock_latency_ns: Latency (in nanoseconds) of switching to this OPP's
* frequency from any other OPP's frequency.
* @required_opps: List of OPPs that are required by this OPP.
@@ -84,6 +86,7 @@ struct dev_pm_opp {
unsigned int level;
struct dev_pm_opp_supply *supplies;
+ struct dev_pm_opp_icc_bw *bandwidth;
unsigned long clock_latency_ns;
@@ -150,6 +153,8 @@ enum opp_table_access {
* @regulator_count: Number of power supply regulators. Its value can be -1
* (uninitialized), 0 (no opp-microvolt property) or > 0 (has opp-microvolt
* property).
+ * @paths: Interconnect path handles
+ * @path_count: Number of interconnect paths
* @genpd_performance_state: Device's power domain support performance state.
* @is_genpd: Marks if the OPP table belongs to a genpd.
* @set_opp: Platform specific set_opp callback
@@ -194,6 +199,8 @@ struct opp_table {
struct clk *clk;
struct regulator **regulators;
int regulator_count;
+ struct icc_path **paths;
+ unsigned int path_count;
bool genpd_performance_state;
bool is_genpd;
@@ -228,12 +235,14 @@ void _of_clear_opp_table(struct opp_table *opp_table);
struct opp_table *_managed_opp(struct device *dev, int index);
void _of_opp_free_required_opps(struct opp_table *opp_table,
struct dev_pm_opp *opp);
+int _of_find_paths(struct opp_table *opp_table, struct device *dev);
#else
static inline void _of_init_opp_table(struct opp_table *opp_table, struct device *dev, int index) {}
static inline void _of_clear_opp_table(struct opp_table *opp_table) {}
static inline struct opp_table *_managed_opp(struct device *dev, int index) { return NULL; }
static inline void _of_opp_free_required_opps(struct opp_table *opp_table,
struct dev_pm_opp *opp) {}
+static inline int _of_find_paths(struct opp_table *opp_table, struct device *dev) { return 0; }
#endif
#ifdef CONFIG_DEBUG_FS
diff --git a/include/linux/pm_opp.h b/include/linux/pm_opp.h
index 24c757a32a7b..dabee09a92b8 100644
--- a/include/linux/pm_opp.h
+++ b/include/linux/pm_opp.h
@@ -43,6 +43,18 @@ struct dev_pm_opp_supply {
unsigned long u_amp;
};
+/**
+ * struct dev_pm_opp_icc_bw - Interconnect bandwidth values
+ * @avg: Average bandwidth corresponding to this OPP (in icc units)
+ * @peak: Peak bandwidth corresponding to this OPP (in icc units)
+ *
+ * This structure stores the bandwidth values for a single interconnect path.
+ */
+struct dev_pm_opp_icc_bw {
+ u32 avg;
+ u32 peak;
+};
+
/**
* struct dev_pm_opp_info - OPP freq/voltage/current values
* @rate: Target clk rate in hz
@@ -127,6 +139,8 @@ struct opp_table *dev_pm_opp_set_regulators(struct device *dev, const char * con
void dev_pm_opp_put_regulators(struct opp_table *opp_table);
struct opp_table *dev_pm_opp_set_clkname(struct device *dev, const char * name);
void dev_pm_opp_put_clkname(struct opp_table *opp_table);
+struct opp_table *dev_pm_opp_set_paths(struct device *dev);
+void dev_pm_opp_put_paths(struct opp_table *opp_table);
struct opp_table *dev_pm_opp_register_set_opp_helper(struct device *dev, int (*set_opp)(struct dev_pm_set_opp_data *data));
void dev_pm_opp_unregister_set_opp_helper(struct opp_table *opp_table);
struct opp_table *dev_pm_opp_set_genpd_virt_dev(struct device *dev, struct device *virt_dev, int index);


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