From: "Guillermo Rodríguez" <guille.rodriguez@gmail•com>
To: Pierre-Yves MORDRET <pierre-yves.mordret@foss•st.com>,
Alain Volmat <alain.volmat@foss•st.com>,
Andi Shyti <andi.shyti@kernel•org>,
Maxime Coquelin <mcoquelin.stm32@gmail•com>,
Alexandre Torgue <alexandre.torgue@foss•st.com>,
Wolfram Sang <wsa@kernel•org>
Cc: "Guillermo Rodríguez" <guille.rodriguez@gmail•com>,
linux-i2c@vger•kernel.org,
linux-stm32@st-md-mailman•stormreply.com,
linux-arm-kernel@lists•infradead.org,
linux-kernel@vger•kernel.org
Subject: [PATCH] i2c: stm32f7: fix timing computation ignoring i2c-analog-filter
Date: Tue, 26 May 2026 11:12:09 +0200 [thread overview]
Message-ID: <20260526091210.20383-1-guille.rodriguez@gmail.com> (raw)
stm32f7_i2c_compute_timing() uses i2c_dev->analog_filter to pick
the analog filter delay, but i2c_dev->analog_filter is parsed from
the "i2c-analog-filter" DT property only after the compute_timing
loop in stm32f7_i2c_setup_timing(), so in practice the timing
calculations always ignore the analog filter. On an STM32MP1 board
with clock-frequency = <400000> and i2c-analog-filter set, measured
SCL frequency was ~382 kHz.
This also affects (widens) the computed SDADEL range. At high bus
clock speeds, this can select an SDADEL value that violates tVD;DAT
(data valid time).
Fix by parsing "i2c-analog-filter" before the compute_timing loop.
Fixes: 83c3408f7b9c ("i2c: stm32f7: support DT binding i2c-analog-filter")
Cc: stable@vger•kernel.org
Signed-off-by: Guillermo Rodríguez <guille.rodriguez@gmail•com>
---
drivers/i2c/busses/i2c-stm32f7.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/i2c/busses/i2c-stm32f7.c b/drivers/i2c/busses/i2c-stm32f7.c
index 53d9df70ebe4..067af255bd22 100644
--- a/drivers/i2c/busses/i2c-stm32f7.c
+++ b/drivers/i2c/busses/i2c-stm32f7.c
@@ -694,6 +694,9 @@ static int stm32f7_i2c_setup_timing(struct stm32f7_i2c_dev *i2c_dev,
if (!of_property_read_bool(i2c_dev->dev->of_node, "i2c-digital-filter"))
i2c_dev->dnf_dt = STM32F7_I2C_DNF_DEFAULT;
+ i2c_dev->analog_filter = of_property_read_bool(i2c_dev->dev->of_node,
+ "i2c-analog-filter");
+
do {
ret = stm32f7_i2c_compute_timing(i2c_dev, setup,
&i2c_dev->timing);
@@ -715,9 +718,6 @@ static int stm32f7_i2c_setup_timing(struct stm32f7_i2c_dev *i2c_dev,
return ret;
}
- i2c_dev->analog_filter = of_property_read_bool(i2c_dev->dev->of_node,
- "i2c-analog-filter");
-
dev_dbg(i2c_dev->dev, "I2C Speed(%i), Clk Source(%i)\n",
setup->speed_freq, setup->clock_src);
dev_dbg(i2c_dev->dev, "I2C Rise(%i) and Fall(%i) Time\n",
--
2.25.1
next reply other threads:[~2026-05-26 9:12 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-26 9:12 Guillermo Rodríguez [this message]
2026-06-03 8:59 ` [PATCH] i2c: stm32f7: fix timing computation ignoring i2c-analog-filter Alain Volmat
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