[PATCH v2] clk: si5351: fail prepare when PLL reset times out

[PATCH v2] clk: si5351: fail prepare when PLL reset times out

[Pengpeng Hou]

The clock prepare path requests a PLL reset when the platform data
requires a deterministic output phase. The reset helper logs polling
errors but returns no status, so prepare still enables the output and
reports success when the reset did not complete.

Return the poll result to prepare, restore the output power-down bit on
failure, and leave the output disabled. XTAL and CLKIN inputs continue
to bypass PLL reset successfully.

The issue was found by our static-analysis tool.

Fixes: 5142cbcea324 ("clk: si5351: Wait for bit clear after PLL reset")
Reviewed-by: Brian Masney <bmasney@redhat.com>
Assisted-by: gpt 5
Signed-off-by: Pengpeng Hou <hppiscas@163.com>
---
Changes since v1:
https://lore.kernel.org/all/20260623135625.49610-1-pengpeng@iscas.ac.cn/
Drop the unrelated alignment change requested by Brian; retain the
bounded prepare failure path.

 drivers/clk/clk-si5351.c |   20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/drivers/clk/clk-si5351.c b/drivers/clk/clk-si5351.c
index 20b0c3c48b86..70daba62305c 100644
--- a/drivers/clk/clk-si5351.c
+++ b/drivers/clk/clk-si5351.c
@@ -907,7 +907,7 @@ static int _si5351_clkout_set_disable_state(
 	return 0;
 }
 
-static void _si5351_clkout_reset_pll(struct si5351_driver_data *drvdata, int num)
+static int _si5351_clkout_reset_pll(struct si5351_driver_data *drvdata, int num)
 {
 	u8 val = si5351_reg_read(drvdata, SI5351_CLK0_CTRL + num);
 	u8 mask = val & SI5351_CLK_PLL_SELECT ? SI5351_PLL_RESET_B :
@@ -918,7 +918,7 @@ static void _si5351_clkout_reset_pll(struct si5351_driver_data *drvdata, int num
 	switch (val & SI5351_CLK_INPUT_MASK) {
 	case SI5351_CLK_INPUT_XTAL:
 	case SI5351_CLK_INPUT_CLKIN:
-		return;  /* pll not used, no need to reset */
+		return 0;  /* pll not used, no need to reset */
 	}
 
 	si5351_reg_write(drvdata, SI5351_PLL_RESET, mask);
@@ -931,6 +931,8 @@ static void _si5351_clkout_reset_pll(struct si5351_driver_data *drvdata, int num
 	dev_dbg(&drvdata->client->dev, "%s - %s: pll = %d\n",
 		__func__, clk_hw_get_name(&drvdata->clkout[num].hw),
 		(val & SI5351_CLK_PLL_SELECT) ? 1 : 0);
+
+	return err;
 }
 
 static int si5351_clkout_prepare(struct clk_hw *hw)
@@ -947,8 +949,18 @@ static int si5351_clkout_prepare(struct clk_hw *hw)
 	 * Do a pll soft reset on the parent pll -- needed to get a
 	 * deterministic phase relationship between the output clocks.
 	 */
-	if (pdata->clkout[hwdata->num].pll_reset)
-		_si5351_clkout_reset_pll(hwdata->drvdata, hwdata->num);
+	if (pdata->clkout[hwdata->num].pll_reset) {
+		int ret;
+
+		ret = _si5351_clkout_reset_pll(hwdata->drvdata, hwdata->num);
+		if (ret) {
+			si5351_set_bits(hwdata->drvdata,
+					SI5351_CLK0_CTRL + hwdata->num,
+					SI5351_CLK_POWERDOWN,
+					SI5351_CLK_POWERDOWN);
+			return ret;
+		}
+	}
 
 	si5351_set_bits(hwdata->drvdata, SI5351_OUTPUT_ENABLE_CTRL,
 			(1 << hwdata->num), 0);

base-commit: 518e5b794c06c0f0eb40df3e202274a66202c137
-- 
2.50.1 (Apple Git-155)

Re: [PATCH v2] clk: si5351: fail prepare when PLL reset times out

[Brian Masney]

On Sun, 20 Sep 2026 11:41:24 +0800, Pengpeng Hou wrote:
> clk: si5351: fail prepare when PLL reset times out

Applied, thanks!

[1/1] clk: si5351: fail prepare when PLL reset times out
      commit: b6685c30d15cd7f28c40b2daaeacc00f21b2f12a

Best regards,
-- 
Brian Masney <bmasney@redhat.com>