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Subject[RESEND PATCH v2 1/4] clk: sprd: check its parent status before reading gate clock
Date
From: Chunyan Zhang <chunyan.zhang@unisoc.com>

Some clocks only can be accessed if their parent is enabled. mipi_csi_xx
clocks on SC9863A are an examples. We have to ensure the parent clock is
enabled when reading those clocks.

Signed-off-by: Chunyan Zhang <chunyan.zhang@unisoc.com>
---
drivers/clk/sprd/gate.c | 7 +++++++
drivers/clk/sprd/gate.h | 9 +++++++++
2 files changed, 16 insertions(+)

diff --git a/drivers/clk/sprd/gate.c b/drivers/clk/sprd/gate.c
index 574cfc116bbc..56e1714b541e 100644
--- a/drivers/clk/sprd/gate.c
+++ b/drivers/clk/sprd/gate.c
@@ -94,8 +94,15 @@ static int sprd_gate_is_enabled(struct clk_hw *hw)
{
struct sprd_gate *sg = hw_to_sprd_gate(hw);
struct sprd_clk_common *common = &sg->common;
+ struct clk_hw *parent;
unsigned int reg;

+ if (sg->flags & SPRD_GATE_NON_AON) {
+ parent = clk_hw_get_parent(hw);
+ if (!parent || !clk_hw_is_enabled(parent))
+ return 0;
+ }
+
regmap_read(common->regmap, common->reg, &reg);

if (sg->flags & CLK_GATE_SET_TO_DISABLE)
diff --git a/drivers/clk/sprd/gate.h b/drivers/clk/sprd/gate.h
index b55817869367..e738dafa4fe9 100644
--- a/drivers/clk/sprd/gate.h
+++ b/drivers/clk/sprd/gate.h
@@ -19,6 +19,15 @@ struct sprd_gate {
struct sprd_clk_common common;
};

+/*
+ * sprd_gate->flags is used for:
+ * CLK_GATE_SET_TO_DISABLE BIT(0)
+ * CLK_GATE_HIWORD_MASK BIT(1)
+ * CLK_GATE_BIG_ENDIAN BIT(2)
+ * so we define new flags from BIT(3)
+ */
+#define SPRD_GATE_NON_AON BIT(3) /* not alway powered on, check before read */
+
#define SPRD_SC_GATE_CLK_HW_INIT_FN(_struct, _name, _parent, _reg, \
_sc_offset, _enable_mask, _flags, \
_gate_flags, _udelay, _ops, _fn) \
--
2.20.1
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