[PATCH v13 1/4] clk: scmi: fix SSC spread conversion
From: Dario Binacchi
Date: Thu Sep 03 2026 - 13:16:05 EST
The spread_bp field of struct clk_spread_spectrum holds the modulation
depth in permyriad (1/100 of a percent), as documented in
clk-provider.h and in the assigned-clock-sscs binding, while the i.MX
SCMI OEM extension expects a value in tenths of a percent, as pointed
out by Peng Fan.
The conversion divides spread_bp by 10000 instead of 10, as reported by
Sashiko, so any valid configuration is truncated to 0 and the hardware
is silently programmed with no spread at all.
Divide by 10 and fix the comment accordingly.
Fixes: 77369b1e6a37 ("clk: scmi: Add i.MX95 OEM extension support for SCMI clock driver")
Reported-by: Sashiko <sashiko-bot@xxxxxxxxxx>
Closes: https://lore.kernel.org/r/20260901155657.6A5981F00A3A@xxxxxxxxxxxxxxx
Reported-by: Peng Fan <peng.fan@xxxxxxx>
Closes: https://lore.kernel.org/r/ZR6PR04MB375776A27E98F140534E8F7FE488B62@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Dario Binacchi <dario.binacchi@xxxxxxxxxxxxxxxxxxxx>
---
Changes in v13:
- Divide spread_bp by 10 instead of 100 as requested by Peng Fan.
- Rename the patch title and reword the description accordingly.
- Add the Reported-by/Closes tags for Sashiko and Peng Fan.
drivers/clk/clk-scmi-oem.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/clk/clk-scmi-oem.c b/drivers/clk/clk-scmi-oem.c
index be11d359b4ec..c1ebbdc6bbc5 100644
--- a/drivers/clk/clk-scmi-oem.c
+++ b/drivers/clk/clk-scmi-oem.c
@@ -39,12 +39,12 @@ scmi_clk_imx_set_spread_spectrum(struct clk_hw *hw,
u32 val;
/*
- * extConfigValue[7:0] - spread percentage (%)
+ * extConfigValue[7:0] - spread percentage in tenths of a percent
* extConfigValue[23:8] - Modulation Frequency
* extConfigValue[24] - Enable/Disable
* extConfigValue[31:25] - Reserved
*/
- val = FIELD_PREP(SCMI_CLOCK_IMX_SS_PERCENTAGE_MASK, ss_conf->spread_bp / 10000);
+ val = FIELD_PREP(SCMI_CLOCK_IMX_SS_PERCENTAGE_MASK, ss_conf->spread_bp / 10);
val |= FIELD_PREP(SCMI_CLOCK_IMX_SS_MOD_FREQ_MASK, ss_conf->modfreq_hz);
if (ss_conf->method != CLK_SPREAD_NO)
val |= SCMI_CLOCK_IMX_SS_ENABLE_MASK;
--
2.43.0