[v3] clk: meson: Fix the determine rate error in clk_regmap_divider_ro_ops

Commit Message

Chuan Liu via B4 Relay Nov. 13, 2024, 9:36 a.m. UTC

From: Chuan Liu <[e-mail]>

The rate determined by calling clk_regmap_divider_ro_ops with
clk_regmap_div_determine_rate is not 'RO', which will result in the
unexpected modification of the frequency of its children when setting
the rate of a clock that references clk_regmap_divider_ro_ops.

Fixes: ea11dda9e091 ("clk: meson: add regmap clocks")
Signed-off-by: Chuan Liu <[e-mail]>
---
Background: During the execution of clk_set_rate(), the function 
clk_core_round_rate_nolock() is called to calculate the matching rate
and save it to 'core->new_rate'. At the same time, it recalculates and
updates its 'child->newrate'. Finally, clk_change_rate() is called to
set all 'new_rates'.
---
Changes in v3:
- Restore clk_regmap_div_determine_rate().
- Link to v2: https://lore.kernel.org/r/2024111[e-mail]

Changes in v2:
- Remove the CLK_DIVIDER_READ_ONLY judgment logic in
clk_regmap_div_determine_rate().
- Add clk_regmap_div_ro_determine_rate().
- Link to v1: https://lore.kernel.org/r/2024111[e-mail]
---
 drivers/clk/meson/clk-regmap.c | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)


---
base-commit: 664988eb47dd2d6ae1d9e4188ec91832562f8f26
change-id: 20241111-fix_childclk_of_roclk_has_been_tampered_with-61dbcc623746

Best regards,

Patch

diff --git a/drivers/clk/meson/clk-regmap.c b/drivers/clk/meson/clk-regmap.c
index 07f7e441b916..2b0b4eb0a3f0 100644
--- a/drivers/clk/meson/clk-regmap.c
+++ b/drivers/clk/meson/clk-regmap.c
@@ -127,9 +127,28 @@  const struct clk_ops clk_regmap_divider_ops = {
 };
 EXPORT_SYMBOL_NS_GPL(clk_regmap_divider_ops, CLK_MESON);
 
+static int clk_regmap_div_ro_determine_rate(struct clk_hw *hw,
+					    struct clk_rate_request *req)
+{
+	struct clk_regmap *clk = to_clk_regmap(hw);
+	struct clk_regmap_div_data *div = clk_get_regmap_div_data(clk);
+	unsigned int val;
+	int ret;
+
+	ret = regmap_read(clk->map, div->offset, &val);
+	if (ret)
+		return ret;
+
+	val >>= div->shift;
+	val &= clk_div_mask(div->width);
+
+	return divider_ro_determine_rate(hw, req, div->table, div->width,
+					 div->flags, val);
+}
+
 const struct clk_ops clk_regmap_divider_ro_ops = {
 	.recalc_rate = clk_regmap_div_recalc_rate,
-	.determine_rate = clk_regmap_div_determine_rate,
+	.determine_rate = clk_regmap_div_ro_determine_rate,
 };
 EXPORT_SYMBOL_NS_GPL(clk_regmap_divider_ro_ops, CLK_MESON);