linux-kernel - [PATCH] clk: Warn and add workaround on misuse of .parent

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Date:   Tue,  8 Nov 2022 21:49:18 +0100
From:   Christian Marangi <ansuelsmth@...il.com>
To:     Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>, linux-clk@...r.kernel.org,
        linux-kernel@...r.kernel.org, Robert Marko <robimarko@...il.com>
Cc:     Christian Marangi <ansuelsmth@...il.com>
Subject: [PATCH] clk: Warn and add workaround on misuse of .parent_data with .name only

By a simple mistake in a .parent_names to .parent_data conversion it was
found that clk core assume fw_name is always provided with a parent_data
struct for each parent and never fallback to .name to get parent name even
if declared.

This is caused by clk_core_get that only checks for parent .fw_name and
doesn't handle .name.

While it's sane to request the dev to correctly do the conversion and
add both .fw_name and .name in a parent_data struct, it's not sane to
silently drop parents without a warning.

Fix this in 2 ways. Add a kernel warning when a wrong implementation is
used and copy .name in .fw_name in parent map populate function to
handle clk problems and malfunctions.

Signed-off-by: Christian Marangi <ansuelsmth@...il.com>
---
 drivers/clk/clk.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index 57b83665e5c3..dccd4ea6f692 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -4015,10 +4015,21 @@ static int clk_core_populate_parent_map(struct clk_core *core,
 			ret = clk_cpy_name(&parent->name, parent_names[i],
 					   true);
 		} else if (parent_data) {
+			const char *parent_name;
+
 			parent->hw = parent_data[i].hw;
 			parent->index = parent_data[i].index;
+			parent_name = parent_data[i].fw_name;
+
+			if (!parent_name && parent_data[i].name) {
+				WARN(1, "Empty .fw_name with .name in %s's .parent_data. Using .name for .fw_name declaration.\n",
+				     core->name);
+				parent_name = parent_data[i].name;
+			}
+
 			ret = clk_cpy_name(&parent->fw_name,
-					   parent_data[i].fw_name, false);
+					   parent_name, false);
+
 			if (!ret)
 				ret = clk_cpy_name(&parent->name,
 						   parent_data[i].name,
-- 
2.37.2