Hi,
On Wednesday, October 06, 2010, Nishanth Menon wrote:
> SoCs have a standard set of tuples consisting of frequency and
> voltage pairs that the device will support per voltage domain. These
> are called Operating Performance Points or OPPs. The actual
> definitions of OPP varies over silicon versions. For a specific domain,
> we can have a set of {frequency, voltage} pairs. As the kernel boots
> and more information is available, a default set of these are activated
> based on the precise nature of device. Further on operation, based on
> conditions prevailing in the system (such as temperature), some OPP
> availability may be temporarily controlled by the SoC frameworks.
>
> To implement an OPP, some sort of power management support is necessary
> hence this library depends on CONFIG_PM.
The patch generally looks good to me, I only have a couple of cosmetic remarks
(below).
...
> +static int opp_set_availability(struct device *dev, unsigned long freq,
> + bool availability_req)
> +{
> + struct device_opp *tmp_dev_opp, *dev_opp = NULL;
> + struct opp *new_opp, *tmp_opp, *opp = ERR_PTR(-ENODEV);
> + int r = 0;
> +
> + /* keep the node allocated */
> + new_opp = kmalloc(sizeof(struct opp), GFP_KERNEL);
> + if (!new_opp) {
> + pr_warning("Unable to allocate opp\n");
Please add an identification string to the messages, something like
"OPP: Unable to allocat object\n" (and similarly in the other messages).
That would help to find the source of a message in case there's any problem.
> + return -ENOMEM;
> + }
> +
> + mutex_lock(&dev_opp_list_lock);
> +
> + /* Find the device_opp */
> + list_for_each_entry(tmp_dev_opp, &dev_opp_list, node) {
> + if (dev == tmp_dev_opp->dev) {
> + dev_opp = tmp_dev_opp;
> + break;
> + }
> + }
> + if (IS_ERR(dev_opp)) {
> + r = PTR_ERR(dev_opp);
> + pr_warning("Unable to find device\n");
> + goto out1;
I'd prefer this lable to be called "unlock". It will be a bit more informative.
> + }
> +
> + /* Do we have the frequency? */
> + list_for_each_entry(tmp_opp, &dev_opp->opp_list, node) {
> + if (tmp_opp->rate == freq) {
> + opp = tmp_opp;
> + break;
> + }
> + }
> + if (IS_ERR(opp)) {
> + r = PTR_ERR(opp);
> + goto out1;
> + }
> +
> + /* Is update really needed? */
> + if (opp->available == availability_req)
> + goto out1;
> + /* copy the old data over */
> + *new_opp = *opp;
> +
> + /* plug in new node */
> + new_opp->available = availability_req;
> +
> + list_replace_rcu(&opp->node, &new_opp->node);
> + mutex_unlock(&dev_opp_list_lock);
> + synchronize_rcu();
> +
> + /* clean up old opp */
> + new_opp = opp;
> + goto out;
> +
> +out1:
+unlock:
> + mutex_unlock(&dev_opp_list_lock);
> +out:
> + kfree(new_opp);
> + return r;
> +}
Thanks,
Rafael
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