Re: [PATCH v7 4/7] OPP: Add support for parsing interconnect bandwidth

Matthias Kaehlcke
2020-04-24T19:20:31Z

Hi,

On Fri, Apr 24, 2020 at 06:54:01PM +0300, 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.
>
> Signed-off-by: Georgi Djakov <georgi.djakov@linaro.org>
> ---
> v7:
> * Addressed some review comments from Viresh and Sibi.
> * Various other changes.
>
> v2: https://lore.kernel.org/linux-arm-msm/20190423132823.7915-4-georgi.djakov@linaro.org/
>
> drivers/opp/Kconfig | 1 +
> drivers/opp/core.c | 16 +++++-
> drivers/opp/of.c | 119 ++++++++++++++++++++++++++++++++++++++++-
> drivers/opp/opp.h | 9 ++++
> include/linux/pm_opp.h | 12 +++++
> 5 files changed, 153 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/opp/Kconfig b/drivers/opp/Kconfig
> index 35dfc7e80f92..230d2b84436c 100644
> --- a/drivers/opp/Kconfig
> +++ b/drivers/opp/Kconfig
> @@ -2,6 +2,7 @@
> config PM_OPP
> bool
> select SRCU
> + depends on INTERCONNECT || !INTERCONNECT

huh?

> ---help---
> SOCs have a standard set of tuples consisting of frequency and
> voltage pairs that the device will support per voltage domain. This
> diff --git a/drivers/opp/core.c b/drivers/opp/core.c
> index c9c1bbe6ae27..8e86811eb7b2 100644
> --- a/drivers/opp/core.c
> +++ b/drivers/opp/core.c
> @@ -985,6 +985,12 @@ static struct opp_table *_allocate_opp_table(struct device *dev, int index)
> ret);
> }
>
> + /* Find interconnect path(s) for the device */
> + ret = _of_find_paths(opp_table, dev);
> + if (ret)
> + dev_dbg(dev, "%s: Error finding interconnect paths: %d\n",
> + __func__, ret);

why dev_dbg and not dev_warn?

> +
> BLOCKING_INIT_NOTIFIER_HEAD(&opp_table->head);
> INIT_LIST_HEAD(&opp_table->opp_list);
> kref_init(&opp_table->kref);
> @@ -1229,19 +1235,22 @@ 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);
> + opp = kzalloc(sizeof(*opp) + supply_size + icc_size, GFP_KERNEL);
> +
> if (!opp)
> 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->supplies + 1);

IIUC this needs to be:

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

maybe s/count/supply_count/

> INIT_LIST_HEAD(&opp->node);
>
> return opp;
> @@ -1276,6 +1285,9 @@ int _opp_compare_key(struct dev_pm_opp *opp1, struct dev_pm_opp *opp2)
> {
> if (opp1->rate != opp2->rate)
> return opp1->rate < opp2->rate ? -1 : 1;
> + if (opp1->bandwidth && opp2->bandwidth &&
> + opp1->bandwidth[0].peak != opp2->bandwidth[0].peak)
> + return opp1->bandwidth[0].peak < opp2->bandwidth[0].peak ? -1 : 1;
> if (opp1->level != opp2->level)
> return opp1->level < opp2->level ? -1 : 1;
> return 0;
> diff --git a/drivers/opp/of.c b/drivers/opp/of.c
> index e33169c7e045..978e445b0cdb 100644
> --- a/drivers/opp/of.c
> +++ b/drivers/opp/of.c
> @@ -332,6 +332,59 @@ 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)

nit: _of_find_icc_paths() to be more concise?

> +{
> + struct device_node *np;
> + int ret, i, count, num_paths;
> +
> + np = of_node_get(dev->of_node);
> + if (!np)
> + return 0;
> +
> + count = of_count_phandle_with_args(np, "interconnects",
> + "#interconnect-cells");
> + of_node_put(np);
> + if (count < 0)
> + return 0;
> +
> + /* two phandles when #interconnect-cells = <1> */
> + if (count % 2) {
> + dev_err(dev, "%s: Invalid interconnects values\n",
> + __func__);

nit: no need for separate line

> + return -EINVAL;
> + }
> +
> + num_paths = count / 2;
> + opp_table->paths = kcalloc(num_paths, sizeof(*opp_table->paths),
> + GFP_KERNEL);

Add kfree(opp_table->paths) to _opp_table_kref_release() ?

> + if (!opp_table->paths)
> + return -ENOMEM;
> +
> + for (i = 0; i < num_paths; 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: Unable to get path%d: %d\n",
> + __func__, i, ret);
> + }

nit: curly braces not needed

> + goto err;
> + }
> + }
> + opp_table->path_count = num_paths;
> +
> + return 0;
> +
> +err:
> + while (i--)
> + icc_put(opp_table->paths[i]);
> +
> + kfree(opp_table->paths);
> + opp_table->paths = NULL;
> +
> + return ret;
> +}
> +
> static bool _opp_is_supported(struct device *dev, struct opp_table *opp_table,
> struct device_node *np)
> {
> @@ -524,8 +577,11 @@ EXPORT_SYMBOL_GPL(dev_pm_opp_of_remove_table);
> static int _read_opp_key(struct dev_pm_opp *new_opp, struct device_node *np,
> bool *rate_not_available)
> {
> + struct property *peak, *avg;
> + u32 *peak_bw, *avg_bw;
> u64 rate;
> - int ret;
> + int ret, i, count;
> + bool found = false;
>
> ret = of_property_read_u64(np, "opp-hz", &rate);
> if (!ret) {
> @@ -535,10 +591,69 @@ static int _read_opp_key(struct dev_pm_opp *new_opp, struct device_node *np,
> * bit guaranteed in clk API.
> */
> new_opp->rate = (unsigned long)rate;
> + found = true;
> }
> *rate_not_available = !!ret;
>
> - of_property_read_u32(np, "opp-level", &new_opp->level);
> + peak = of_find_property(np, "opp-peak-kBps", NULL);
> + if (peak) {
> + /*
> + * Bandwidth consists of peak and average (optional) values:
> + * opp-peak-kBps = <path1_value path2_value>;
> + * opp-avg-kBps = <path1_value path2_value>;
> + */
> + count = peak->length / sizeof(u32);
> + peak_bw = kmalloc_array(count, sizeof(*peak_bw), GFP_KERNEL);
> + if (!peak_bw)
> + return -ENOMEM;
> +
> + ret = of_property_read_u32_array(np, "opp-peak-kBps", peak_bw,
> + count);
> + if (ret) {
> + pr_err("%s: Error parsing opp-peak-kBps: %d\n",
> + __func__, ret);
> + goto free_peak_bw;
> + }
> +
> + for (i = 0; i < count; i++)
> + new_opp->bandwidth[i].peak = kBps_to_icc(peak_bw[i]);
> +
> + found = true;

kfree(peak_bw);

or re-arrange the kfree()'s below to be in the common code path

> + }
> +
> + avg = of_find_property(np, "opp-avg-kBps", NULL);
> + if (peak && avg) {
> + count = avg->length / sizeof(u32);
> + avg_bw = kmalloc_array(count, sizeof(*avg_bw), GFP_KERNEL);
> + if (!avg_bw) {
> + ret = -ENOMEM;
> + goto free_peak_bw;
> + }
> +
> + ret = of_property_read_u32_array(np, "opp-avg-kBps", avg_bw,
> + count);
> + if (ret) {
> + pr_err("%s: Error parsing opp-avg-kBps: %d\n",
> + __func__, ret);
> + goto free_avg_bw;
> + }
> +
> + for (i = 0; i < count; i++)
> + new_opp->bandwidth[i].avg = kBps_to_icc(avg_bw[i]);

kfree(avg_bw);

> + }

nit: the two code blocks for peak and average bandwidth are mostly redundant.
If it weren't for the assignment of 'new_opp->bandwidth[i].avg' vs
'new_opp->bandwidth[i].peak' the above could easily be outsourced into a
helper function. With some pointer hacks you could still do this, but not
sure if it's worth the effort.

> +
> + if (of_property_read_u32(np, "opp-level", &new_opp->level))
> + found = true;
> +
> + if (found)
> + return 0;
> +
> + return ret;
> +
> +free_avg_bw:
> + kfree(avg_bw);
> +free_peak_bw:
> + kfree(peak_bw);
>
> return ret;
> }