linux-kernel - Re: [PATCH v6 1/3] OPP: Add function to look up required OPP's for a given OPP

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Message-ID: <20210204110334.kbsf2wvyv5tvkf46@vireshk-i7>
Date:   Thu, 4 Feb 2021 16:33:34 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Hsin-Yi Wang <hsinyi@...omium.org>
Cc:     Viresh Kumar <vireshk@...nel.org>, linux-pm@...r.kernel.org,
        Nishanth Menon <nm@...com>, Stephen Boyd <sboyd@...nel.org>,
        "Rafael J . Wysocki" <rjw@...ysocki.net>,
        linux-kernel@...r.kernel.org,
        MyungJoo Ham <myungjoo.ham@...sung.com>,
        Kyungmin Park <kyungmin.park@...sung.com>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        Saravana Kannan <saravanak@...gle.com>
Subject: Re: [PATCH v6 1/3] OPP: Add function to look up required OPP's for a
 given OPP

On 04-02-21, 16:14, Hsin-Yi Wang wrote:
> From: Saravana Kannan <saravanak@...gle.com>
> 
> Add a function that allows looking up required OPPs given a source OPP
> table, destination OPP table and the source OPP.
> 
> Signed-off-by: Saravana Kannan <saravanak@...gle.com>
> Signed-off-by: Hsin-Yi Wang <hsinyi@...omium.org>
> ---
>  drivers/opp/core.c     | 59 ++++++++++++++++++++++++++++++++++++++++++
>  include/linux/pm_opp.h |  7 +++++
>  2 files changed, 66 insertions(+)

I made some changes while applying:

diff --git a/drivers/opp/core.c b/drivers/opp/core.c
index fba67ae40aef..c3f3d9249cc5 100644
--- a/drivers/opp/core.c
+++ b/drivers/opp/core.c
@@ -2402,21 +2402,21 @@ EXPORT_SYMBOL_GPL(devm_pm_opp_attach_genpd);
  * dev_pm_opp_xlate_required_opp() - Find required OPP for @src_table OPP.
  * @src_table: OPP table which has @dst_table as one of its required OPP table.
  * @dst_table: Required OPP table of the @src_table.
+ * @src_opp: OPP from the @src_table.
  *
  * This function returns the OPP (present in @dst_table) pointed out by the
- * "required-opps" property of the OPP (present in @src_table).
+ * "required-opps" property of the @src_opp (present in @src_table).
  *
  * The callers are required to call dev_pm_opp_put() for the returned OPP after
  * use.
  *
- * Return: destination table OPP on success, otherwise -EINVAL or -ENODEV based
- * on errors.
+ * Return: pointer to 'struct dev_pm_opp' on success and errorno otherwise.
  */
 struct dev_pm_opp *dev_pm_opp_xlate_required_opp(struct opp_table *src_table,
                                                 struct opp_table *dst_table,
                                                 struct dev_pm_opp *src_opp)
 {
-       struct dev_pm_opp *opp, *dest_opp = ERR_PTR(-EINVAL);
+       struct dev_pm_opp *opp, *dest_opp = ERR_PTR(-ENODEV);
        int i;
 
        if (!src_table || !dst_table || !src_opp ||
@@ -2425,37 +2425,33 @@ struct dev_pm_opp *dev_pm_opp_xlate_required_opp(struct opp_table *src_table,
 
        /* required-opps not fully initialized yet */
        if (lazy_linking_pending(src_table))
-               return ERR_PTR(-EINVAL);
+               return ERR_PTR(-EBUSY);
 
        for (i = 0; i < src_table->required_opp_count; i++) {
-               if (src_table->required_opp_tables[i] == dst_table)
+               if (src_table->required_opp_tables[i] == dst_table) {
+                       mutex_lock(&src_table->lock);
+
+                       list_for_each_entry(opp, &src_table->opp_list, node) {
+                               if (opp == src_opp) {
+                                       dest_opp = opp->required_opps[i];
+                                       dev_pm_opp_get(dest_opp);
+                                       break;
+                               }
+                       }
+
+                       mutex_unlock(&src_table->lock);
                        break;
-       }
-
-       if (unlikely(i == src_table->required_opp_count)) {
-               pr_err("%s: Couldn't find matching OPP table (%p: %p)\n",
-                      __func__, src_table, dst_table);
-               return ERR_PTR(-ENODEV);
-       }
-
-       mutex_lock(&src_table->lock);
-
-       list_for_each_entry(opp, &src_table->opp_list, node) {
-               if (opp == src_opp) {
-                       dest_opp = opp->required_opps[i];
-                       dev_pm_opp_get(dest_opp);
-                       goto unlock;
                }
        }
 
-       pr_err("%s: Couldn't find matching OPP (%p: %p)\n", __func__, src_table,
-              dst_table);
-
-unlock:
-       mutex_unlock(&src_table->lock);
+       if (IS_ERR(dest_opp)) {
+               pr_err("%s: Couldn't find matching OPP (%p: %p)\n", __func__,
+                      src_table, dst_table);
+       }
 
        return dest_opp;
 }
+EXPORT_SYMBOL_GPL(dev_pm_opp_xlate_required_opp);
 
 /**
  * dev_pm_opp_xlate_performance_state() - Find required OPP's pstate for src_table.


-- 
viresh