Doug,
On 20 May 2014 22:18, Doug Anderson dianders@chromium.org wrote:
Is it worth documenting that if we implement target_intermediate() that target_index() must not fail? That means that any failure-prone things (like setting a regulator) should happen in target_index().
You meant target_intermediate() is the last line, right ?
Yeah, we can add that..
- Frequency Table Helpers
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index 9bf12a2..f38f2f2 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -1819,27 +1819,50 @@ EXPORT_SYMBOL(cpufreq_unregister_notifier); static int __target_index(struct cpufreq_policy *policy, struct cpufreq_frequency_table *freq_table, int index) {
struct cpufreq_freqs freqs;
struct cpufreq_freqs freqs = {.old = policy->cur, .flags = 0}; int retval = -EINVAL; bool notify; notify = !(cpufreq_driver->flags & CPUFREQ_ASYNC_NOTIFICATION);if (!notify)goto skip_notify;I'm personally not a fan of using goto here. All you're trying to do is avoiding a level of indentation? If it really matters that much then create a sub function. IMHO goto should generally be reserved for error handling.
Yeah, I was trying that :) .. Another routine wouldn't be right here as the POST_NOTIFICATION will be handled in this routine only.
I will try again to see if I can write some better code here, but wouldn't promise that :)
if (notify) {freqs.old = policy->cur;freqs.new = freq_table[index].frequency;freqs.flags = 0;
/* Handle switching to intermediate frequency */if (cpufreq_driver->get_intermediate) {freqs.new = cpufreq_driver->get_intermediate(policy, index);Would it be worth it to change this to?
intermediate = 0 if (cpufreq_driver->get_intermediate) intermediate = cpufreq_driver->get_intermediate(); if (intermediate)
...the idea being that a driver may use an intermediate frequency for some transitions but not for all. For instance: on tegra if you happen to change to the exact clock frequency of the intermediate PLL it just stays there. There's no need for two notifications in that case. There may be other systems that can optimize some transitions to totally skip the intermediate stage (maybe you've got an non-glitching divider somewhere so you can optimize a transition from 1.4GHz to 700MHz to go w/ no intermediate jump).
Hmm, will try to fix that as well. Looks like a valid point.
pr_debug("%s: cpu: %d, oldfreq: %u, new freq: %u\n",
pr_debug("%s: cpu: %d, switching to intermediate freq: oldfreq: %u, intermediate freq: %u\n", __func__, policy->cpu, freqs.old, freqs.new); cpufreq_freq_transition_begin(policy, &freqs);retval = cpufreq_driver->target_intermediate(policy, freqs.new);It feels like you want to pass in "index" here too, just in case. A driver may need to make decisions about other clocks based on the eventual final frequency. They could cache it themselves from the get_intermediate() call, but that seems ugly.
I had index here initially, but then it looked like they may need to perform get_intermediate() again from this routine and so sending the intermediate freq is probably better. So, probably just wait for some drivers which may need index here ?
@@ -2361,7 +2384,8 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data) !(driver_data->setpolicy || driver_data->target_index || driver_data->target) || (driver_data->setpolicy && (driver_data->target_index ||
driver_data->target)))
driver_data->target)) ||(!!driver_data->get_intermediate ^ !!driver_data->target_intermediate))I'm OK with the !! trick, but using ^ here seems more confusing. Why not use "!="? (!!driver_data->get_intermediate != !!driver_data->target_intermediate))
Will work as well :)