950-0845-clk-Fix-clk_get_parent-documentation.patch

From daba7e69a412a6b55b77818904ae53e2a9a6d91c Mon Sep 17 00:00:00 2001
From: Maxime Ripard <maxime@cerno.tech>
Date: Fri, 1 Apr 2022 11:09:29 +0200
Subject: [PATCH] clk: Fix clk_get_parent() documentation

The clk_get_parent() documentation in the header states that it will
return a valid pointer, or an error pointer on failure.

However, the documentation in the source file, and the code itself, will
return also return NULL if there isn't any parent for that clock. Let's
mention it.

An orphan clock should return NULL too, so let's add a test for it.

Tested-by: Alexander Stein <alexander.stein@ew.tq-group.com> # imx8mp
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com> # exynos4210, meson g12b
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
---
 drivers/clk/clk_test.c | 17 +++++++++++++++++
 include/linux/clk.h    |  5 +++--
 2 files changed, 20 insertions(+), 2 deletions(-)

--- a/drivers/clk/clk_test.c
+++ b/drivers/clk/clk_test.c
@@ -534,6 +534,22 @@ clk_orphan_transparent_multiple_parent_m
 
 /*
  * Test that, for a mux whose current parent hasn't been registered yet,
+ * clk_get_parent() will return NULL.
+ */
+static void
+clk_test_orphan_transparent_multiple_parent_mux_get_parent(struct kunit *test)
+{
+	struct clk_multiple_parent_ctx *ctx = test->priv;
+	struct clk_hw *hw = &ctx->hw;
+	struct clk *clk = hw->clk;
+	struct clk *parent;
+
+	parent = clk_get_parent(clk);
+	KUNIT_EXPECT_PTR_EQ(test, parent, NULL);
+}
+
+/*
+ * Test that, for a mux whose current parent hasn't been registered yet,
  * calling clk_set_parent() to a valid parent will properly update the
  * mux parent and its orphan status.
  */
@@ -642,6 +658,7 @@ clk_test_orphan_transparent_multiple_par
 }
 
 static struct kunit_case clk_orphan_transparent_multiple_parent_mux_test_cases[] = {
+	KUNIT_CASE(clk_test_orphan_transparent_multiple_parent_mux_get_parent),
 	KUNIT_CASE(clk_test_orphan_transparent_multiple_parent_mux_set_parent),
 	KUNIT_CASE(clk_test_orphan_transparent_multiple_parent_mux_set_parent_get_rate),
 	KUNIT_CASE(clk_test_orphan_transparent_multiple_parent_mux_set_parent_set_range_modified),
--- a/include/linux/clk.h
+++ b/include/linux/clk.h
@@ -829,8 +829,9 @@ int clk_set_parent(struct clk *clk, stru
  * clk_get_parent - get the parent clock source for this clock
  * @clk: clock source
  *
- * Returns struct clk corresponding to parent clock source, or
- * valid IS_ERR() condition containing errno.
+ * Returns struct clk corresponding to parent clock source, a NULL
+ * pointer if it doesn't have a parent, or a valid IS_ERR() condition
+ * containing errno.
  */
 struct clk *clk_get_parent(struct clk *clk);