clk: mediatek: fix mux clocks with mapped parent IDs

Pass the unmapped parent ID when setting parent for mux clocks.

For technical reasons, some Mediatek clock driver have a mapping between
the clock IDs used in the devicetree and ID used in the generic clock
framework.

The mtk_clk_mux_set_parent() function is comparing the passed mapped
parent ID against the unmapped IDs in the chip-specific data structures.
Before this change, we were passing the mapped parent ID. When there is
a mapping, this resulted in buggy behavior (usually just incorrectly
failing to find a match and returning an error). We need to pass the
unmapped ID of the parent clock instead for the matching to work
correctly.

Since the reverse lookup is a bit verbose, a helper function is added to
keep the code clean.

Fixes: b1358915728b ("clk: mediatek: add of_xlate ops")
Signed-off-by: David Lechner <dlechner@baylibre.com>

diff --git a/drivers/clk/mediatek/clk-mtk.c b/drivers/clk/mediatek/clk-mtk.c
index 82306ae285cd762f1c6ac7b1f87cb7eba03f027c..acc28d1da1a09a3afe3af6b7813bc6919f01c5fa 100644 (file)
--- a/drivers/clk/mediatek/clk-mtk.c
+++ b/drivers/clk/mediatek/clk-mtk.c
@@ -66,6 +66,24 @@ static const int mtk_common_clk_of_xlate(struct clk *clk,
        return 0;
 }
 
+static int mtk_common_clk_get_unmapped_id(struct clk *clk)
+{
+       struct mtk_clk_priv *priv = dev_get_priv(clk->dev);
+       const struct mtk_clk_tree *tree = priv->tree;
+       int i;
+
+       if (!tree->id_offs_map)
+               return clk->id;
+
+       /* Perform reverse lookup of unmapped ID. */
+       for (i = 0; i < tree->id_offs_map_size; i++) {
+               if (tree->id_offs_map[i] == clk->id)
+                       return i;
+       }
+
+       return -ENOENT;
+}
+
 static int mtk_dummy_enable(struct clk *clk)
 {
        return 0;
@@ -812,6 +830,7 @@ static int mtk_common_clk_set_parent(struct clk *clk, struct clk *parent)
 {
        struct mtk_clk_priv *parent_priv = dev_get_priv(parent->dev);
        struct mtk_clk_priv *priv = dev_get_priv(clk->dev);
+       int parent_unmapped_id;
        u32 parent_type;
 
        if (!priv->tree->muxes || clk->id < priv->tree->muxes_offs ||
@@ -821,8 +840,12 @@ static int mtk_common_clk_set_parent(struct clk *clk, struct clk *parent)
        if (!parent_priv)
                return 0;
 
+       parent_unmapped_id = mtk_common_clk_get_unmapped_id(parent);
+       if (parent_unmapped_id < 0)
+               return parent_unmapped_id;
+
        parent_type = parent_priv->tree->flags & CLK_PARENT_MASK;
-       return mtk_clk_mux_set_parent(priv->base, parent->id, parent_type,
+       return mtk_clk_mux_set_parent(priv->base, parent_unmapped_id, parent_type,
                        &priv->tree->muxes[clk->id - priv->tree->muxes_offs]);
 }