Hi Daniel,

On Mon, Dec 7, 2015 at 10:44 AM, Daniel Kurtz [off-list ref] wrote:

Hi Pi-Cheng,

On Sat, Dec 5, 2015 at 2:01 PM, Pi-Cheng Chen [off-list ref] wrote:

quoted

Since the return value of ->init() of cpufreq driver is not propagated
to the device driver model now, move resources allocation into
->probe() to handle -EPROBE_DEFER properly.

Signed-off-by: Pi-Cheng Chen <redacted>
---
v1->v2:
- fix error handling path in ->probe()
---
 drivers/cpufreq/mt8173-cpufreq.c | 98 ++++++++++++++++++++++++++++------------
 1 file changed, 70 insertions(+), 28 deletions(-)

diff --git a/drivers/cpufreq/mt8173-cpufreq.c b/drivers/cpufreq/mt8173-cpufreq.c
index 9d0fe37..257bcb9 100644
--- a/drivers/cpufreq/mt8173-cpufreq.c
+++ b/drivers/cpufreq/mt8173-cpufreq.c

@@ -41,16 +41,35 @@
  * the original PLL becomes stable at target frequency.
  */
 struct mtk_cpu_dvfs_info {
+       struct cpumask cpus;
        struct device *cpu_dev;
        struct regulator *proc_reg;
        struct regulator *sram_reg;
        struct clk *cpu_clk;
        struct clk *inter_clk;
        struct thermal_cooling_device *cdev;
+       struct list_head list_head;
        int intermediate_voltage;
        bool need_voltage_tracking;
 };

+static LIST_HEAD(dvfs_info_list);

This struct is specific to this driver, so:

mtk_cpu_dvfs_info_list

That's fair. Both work for me.
But since it's a static variable, I prefer the shorter name since it won't
be misunderstood.

quoted

+
+struct mtk_cpu_dvfs_info *get_dvfs_info(int cpu)

static

Will do it.

Also, it would be clearer to name this function something like
"mtk_cpu_dfs_info_lookup" since "mtk_cpu_dfs_info" is the type this
function looks up in the list.
It would also match the other functions such as "mtk_cpu_dvfs_info_init()".

mtk_cpu_dvfs_info_lookup() looks good to me.
WIll do it.

quoted

+{
+       struct mtk_cpu_dvfs_info *info;
+       struct list_head *list;
+
+       list_for_each(list, &dvfs_info_list) {
+               info = list_entry(list, struct mtk_cpu_dvfs_info, list_head);
+
+               if (cpumask_test_cpu(cpu, &info->cpus))
+                       return info;
+       }
+
+       return NULL;
+}
+
 static int mtk_cpufreq_voltage_tracking(struct mtk_cpu_dvfs_info *info,
                                        int new_vproc)
 {

@@ -402,6 +421,9 @@ static int mtk_cpu_dvfs_info_init(struct mtk_cpu_dvfs_info *info, int cpu)
         */
        info->need_voltage_tracking = !IS_ERR(sram_reg);

+       /* CPUs in the same cluster share a clock and power domain. */
+       cpumask_copy(&info->cpus, &cpu_topology[cpu].core_sibling);
+
        return 0;

 out_free_opp_table:

@@ -440,47 +462,32 @@ static int mtk_cpufreq_init(struct cpufreq_policy *policy)
        struct cpufreq_frequency_table *freq_table;
        int ret;

-       info = kzalloc(sizeof(*info), GFP_KERNEL);
-       if (!info)
-               return -ENOMEM;
-
-       ret = mtk_cpu_dvfs_info_init(info, policy->cpu);
-       if (ret) {
-               pr_err("%s failed to initialize dvfs info for cpu%d\n",
-                      __func__, policy->cpu);
-               goto out_free_dvfs_info;
+       info = get_dvfs_info(policy->cpu);
+       if (!info) {
+               pr_err("dvfs info for cpu%d is not initialized.\n",
+                      policy->cpu);
+               return -EINVAL;
        }

        ret = dev_pm_opp_init_cpufreq_table(info->cpu_dev, &freq_table);

Hmm. Does this change at init() time?  Or can we move this to probe(), too?

It doesn't change at init() time for MT8173 since we don't add OPP
dynamically and I don't see any problem to move it. I will move it to probe().

quoted

        if (ret) {
                pr_err("failed to init cpufreq table for cpu%d: %d\n",
                       policy->cpu, ret);
-               goto out_release_dvfs_info;
+               return ret;
        }

        ret = cpufreq_table_validate_and_show(policy, freq_table);
        if (ret) {
                pr_err("%s: invalid frequency table: %d\n", __func__, ret);
-               goto out_free_cpufreq_table;
+               dev_pm_opp_free_cpufreq_table(info->cpu_dev, &freq_table);
+               return ret;

If dev_pm_opp_init_cpufreq_table() really is needed at init() time,
then please don't change this; still use "goto out_free_cpufreq_table"
here.

quoted

        }

-       /* CPUs in the same cluster share a clock and power domain. */
-       cpumask_copy(policy->cpus, &cpu_topology[policy->cpu].core_sibling);
+       cpumask_copy(policy->cpus, &info->cpus);
        policy->driver_data = info;
        policy->clk = info->cpu_clk;

        return 0;
-
-out_free_cpufreq_table:
-       dev_pm_opp_free_cpufreq_table(info->cpu_dev, &freq_table);
-
-out_release_dvfs_info:
-       mtk_cpu_dvfs_info_release(info);
-
-out_free_dvfs_info:
-       kfree(info);
-
-       return ret;
 }

 static int mtk_cpufreq_exit(struct cpufreq_policy *policy)

@@ -489,8 +496,6 @@ static int mtk_cpufreq_exit(struct cpufreq_policy *policy)

        cpufreq_cooling_unregister(info->cdev);
        dev_pm_opp_free_cpufreq_table(info->cpu_dev, &policy->freq_table);
-       mtk_cpu_dvfs_info_release(info);
-       kfree(info);

        return 0;
 }

@@ -510,11 +515,48 @@ static struct cpufreq_driver mt8173_cpufreq_driver = {

 static int mt8173_cpufreq_probe(struct platform_device *pdev)
 {
-       int ret;
+       struct mtk_cpu_dvfs_info *info;
+       struct list_head *list, *tmp;
+       int cpu, ret;
+
+       for_each_possible_cpu(cpu) {

Is there an iterator for cpu clusters?  Would be useful here.

Or, even better:
 * Is there a way to way to map cpu to cpu cluster ID?
 * Is there a way to count the number of clusters?
If so you can just use an array of mtk_cpu_dvfs_info, and use a cpu's
cluster ID as its index into the array.

As I originally planned, this driver should be easily extended support
for other
Mediatek platforms. For this reason, we should not assume there's a fixed
mapping for CPU ID and cluster ID and the CPU DVFS domain and cluster neither.
Furthermore, the CPU DVFS domain sharing information will be provided by
operating-points-v2 bindings on which I am working to migrate mt8173-cpufreq
driver. We should not put the same information in two different places.

quoted

+               info = get_dvfs_info(cpu);
+               if (info)
+                       continue;

How could this ever return non-NULL?
This is probe; it won't be called twice - not unless a prior probe()
failed (and/or after .remove()), right?

Yes. it does return non-NULL for CPU1 and CPU3.
When it goes into the loop with cpu=0, mtk_cpu_dvfs_info_init() will copy the
cluster core_sibling mask to info->cpus:

cpumask_copy(&info->cpus, &cpu_topology[cpu].core_sibling);

which means cpu0 and cpu1 share this struct mtk_cpu_dvfs_info variable.
So when it goes into the loop with cpu=1, get_dvfs_info() will return the shared
data structure. Similar for CPU2 and CPU3.

BTW, the shared information from core_sibling cpumask will be replaced by
operating-points-v2 bindings later.

quoted

+
+               info = kzalloc(sizeof(*info), GFP_KERNEL);

devm_kzalloc() (and you can then remove the kfree()'s below).

Yes. Will do it.

quoted

+               if (!info) {
+                       ret = -ENOMEM;
+                       goto release_dvfs_info_list;
+               }
+
+               ret = mtk_cpu_dvfs_info_init(info, cpu);
+               if (ret) {
+                       pr_err("%s failed to initialize dvfs info for cpu%d\n",
+                              __func__, cpu);

dev_err(&pdev->dev, ) here and elsewhere.

Will do it.
Thanks for reviewing.

Pi-Cheng

-Dan

quoted

+                       kfree(info);
+                       goto release_dvfs_info_list;
+               }
+
+               list_add(&info->list_head, &dvfs_info_list);
+       }

        ret = cpufreq_register_driver(&mt8173_cpufreq_driver);
-       if (ret)
+       if (ret) {
                pr_err("failed to register mtk cpufreq driver\n");
+               goto release_dvfs_info_list;
+       }
+
+       return 0;
+
+release_dvfs_info_list:
+       list_for_each_safe(list, tmp, &dvfs_info_list) {
+               info = list_entry(list, struct mtk_cpu_dvfs_info, list_head);
+
+               mtk_cpu_dvfs_info_release(info);
+               list_del(list);
+               kfree(info);
+       }

        return ret;
 }
--
1.9.1