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SubjectRe: [PATCH 2/3] PM / OPP: Parse 'opp-supported-hw' binding
On 11/16, Viresh Kumar wrote:
> @@ -834,6 +837,150 @@ static int opp_parse_supplies(struct dev_pm_opp *opp, struct device *dev)
> }
>
> /**
> + * dev_pm_opp_set_supported_hw() - Set supported platforms
> + * @dev: Device for which the regulator has to be set.
> + * @versions: Array of hierarchy of versions to match.
> + * @count: Number of elements in the array.
> + *
> + * This is required only for the V2 bindings, and it enables a platform to
> + * specify the hierarchy of versions it supports. OPP layer will then enable
> + * OPPs, which are available for those versions, based on its 'opp-supported-hw'
> + * property.
> + */
> +int dev_pm_opp_set_supported_hw(struct device *dev, u32 *versions,

versions could be const.

> + unsigned int count)
> +{
> + struct device_opp *dev_opp;
> + int ret = 0;
> +
> + if (!dev || !versions || !count) {
> + pr_err("%s: Invalid arguments, dev:0x%p, ver:0x%p, count:%u\n",
> + __func__, dev, versions, count);

Weird 0x(null) prints may be here. Do we really need this check
at all though? Users should know what they're doing.

> + return -EINVAL;
> + }
> +
> + /* Operations on OPP structures must be done from within rcu locks */
> + rcu_read_lock();
> +
> + dev_opp = _add_device_opp(dev);
> + if (!dev_opp)
> + return -ENOMEM;
> +
> + /* Do we already have a version hierarchy associated with dev_opp? */
> + if (dev_opp->supported_hw) {
> + dev_err(dev, "%s: Already have supported hardware list\n",
> + __func__);
> + ret = -EINVAL;

Maybe -EBUSY is more appropriate?

> + goto unlock;
> + }
> +
> + dev_opp->supported_hw = kmemdup(versions, count * sizeof(*versions),
> + GFP_KERNEL);
> + if (!dev_opp->supported_hw) {
> + ret = -ENOMEM;
> + goto unlock;
> + }
> +
> + dev_opp->supported_hw_count = count;
> +
> +unlock:
> + rcu_read_unlock();
> +
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(dev_pm_opp_set_supported_hw);
> +
> +/**
> + * dev_pm_opp_put_supported_hw() - Releases resources blocked for supported hw
> + * @dev: Device for which the regulator has to be set.

regulator or OPP?

> + *
> + * This is required only for the V2 bindings, and is called for a matching
> + * dev_pm_opp_set_supported_hw(). Until this is called, the device_opp structure
> + * will not be freed.
> + */
> +void dev_pm_opp_put_supported_hw(struct device *dev)
> +{
> + struct device_opp *dev_opp;
> +
> + if (!dev) {
> + pr_err("%s: Invalid argument dev:0x%p\n", __func__, dev);

dev is NULL.. so this prints :0x(null) all the time? And really,
who is calling this with a NULL dev?

> + return;
> + }
> +
> + /* Operations on OPP structures must be done from within rcu locks */
> + rcu_read_lock();
> +
> + /* Check for existing list for 'dev' first */
> + dev_opp = _find_device_opp(dev);

Plus this checks for a NULL dev so we really don't need that
check for a NULL dev at the top at all.

> + if (IS_ERR(dev_opp)) {
> + dev_err(dev, "Failed to find dev_opp: %ld\n", PTR_ERR(dev_opp));
> + goto unlock;
> + }
> +
[...]
> +
> +static bool _opp_is_supported(struct device *dev, struct device_opp *dev_opp,
> + struct device_node *np)
> +{
> + unsigned int count;
> + u32 *versions;
> + bool supported = true;
> + int ret;
> +
> + if (!dev_opp->supported_hw)
> + return true;
> +
> + count = of_property_count_u32_elems(np, "opp-supported-hw");
> + if (count != dev_opp->supported_hw_count) {
> + dev_warn(dev, "%s: supported-hw count mismatch, plat:%u != DT:%u\n",
> + __func__, dev_opp->supported_hw_count, count);
> + return false;
> + }
> +
> + versions = kcalloc(count, sizeof(*versions), GFP_KERNEL);
> + if (!versions)
> + return false;
> +
> + ret = of_property_read_u32_array(np, "opp-supported-hw", versions,
> + count);
> + if (ret) {
> + dev_warn(dev, "%s: failed to read opp-supported-hw property: %d\n",
> + __func__, ret);
> + supported = false;
> + goto free_versions;
> + }
> +
> + while (count--) {
> + /* Both of these are bitwise masks of the versions */
> + if (!(versions[count] & dev_opp->supported_hw[count])) {
> + supported = false;
> + break;
> + }
> + }
> +
> +free_versions:
> + kfree(versions);

Why do we need to allocate an array to check the property a u32
at a time? We should be able to call of_property_read_u32_index()
in a loop and check that against the version array. No allocation
needed.

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


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