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

From: Rajendra Nayak
Date: Wed Jul 17 2019 - 06:04:47 EST

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++;

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