Re: [PATCH] opp: Return genpd virtual devices from dev_pm_opp_attach_genpd()

[Rajendra Nayak]

On 7/17/2019 11:17 AM, Viresh Kumar wrote:

On 11-07-19, 15:09, Rajendra Nayak wrote:

Sorry for the delay

Same here :)

I seem to have completely missed this patch.
I just gave this a try and here are some observations,

I have a case where I have one device with 2 power domains, one of them
is scale-able (supports perf state) and the other one supports only being
turned on and off.

1. In the driver I now need to use dev_pm_domain_attach_by_name/id to attach the
power domain which supports only on/off and then use dev_pm_opp_attach_genpd()
for the one which supports perf states.

2. My OPP table has only 1 required_opps, so the required_opp_count for the OPP 
table is 1.
Now if my device tree has my scale-able powerdomain at index 1 (it works if its 
at index 0)
then I end up with this error

[    2.858628] ufshcd-qcom 1d84000.ufshc: Index can't be greater than 
required-opp-count - 1, rpmh_pd (1 : 1)

so it looks like a lot of the OPP core today just assumes that if a device has 
multiple power domains,
all of them are scale-able which isn't necessarily true.

I don't think a lot of OPP core has these problems, but maybe only
this place. I was taking care of this since the beginning just forgot
it now.

What about this over this commit:

Yes, this does seem to fix my concern mentioned in 2. above.

diff --git a/drivers/opp/core.c b/drivers/opp/core.c
index d76ead4eff4c..1f11f8c92337 100644
--- a/drivers/opp/core.c
+++ b/drivers/opp/core.c
@@ -1789,13 +1789,16 @@ static void _opp_detach_genpd(struct opp_table 
*opp_table)
   *
   * This helper needs to be called once with a list of all genpd to attach.
   * Otherwise the original device structure will be used instead by the OPP 
core.
+ *
+ * The order of entries in the names array must match the order in which
+ * "required-opps" are added in DT.
   */
  struct opp_table *dev_pm_opp_attach_genpd(struct device *dev,
                 const char **names, struct device ***virt_devs)
  {
         struct opp_table *opp_table;
         struct device *virt_dev;
-       int index, ret = -EINVAL;
+       int index = 0, ret = -EINVAL;
         const char **name = names;

opp_table = dev_pm_opp_get_opp_table(dev);

@@ -1821,14 +1824,6 @@ struct opp_table *dev_pm_opp_attach_genpd(struct device 
*dev,
                 goto unlock;

while (*name) {

-               index = of_property_match_string(dev->of_node,
-                                                "power-domain-names", *name);
-               if (index < 0) {
-                       dev_err(dev, "Failed to find power domain: %s (%d)\n",
-                               *name, index);
-                       goto err;
-               }
-
                 if (index >= opp_table->required_opp_count) {
                         dev_err(dev, "Index can't be greater than 
required-opp-count - 1, %s (%d : %d)\n",
                                 *name, opp_table->required_opp_count, index);
@@ -1849,6 +1844,7 @@ struct opp_table *dev_pm_opp_attach_genpd(struct device 
*dev,
                 }

opp_table->genpd_virt_devs[index] = virt_dev;

+               index++;
                 name++;
         }

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