From: Alain Volmat <alain.volmat@foss•st.com>
To: "Guillermo Rodríguez" <guille.rodriguez@gmail•com>
Cc: Pierre-Yves MORDRET <pierre-yves.mordret@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>, <linux-i2c@vger•kernel.org>,
<linux-stm32@st-md-mailman•stormreply.com>,
<linux-arm-kernel@lists•infradead.org>,
<linux-kernel@vger•kernel.org>
Subject: Re: [PATCH] i2c: stm32f7: fix timing computation ignoring i2c-analog-filter
Date: Wed, 3 Jun 2026 10:59:14 +0200 [thread overview]
Message-ID: <ah_s4nd99Bit9eAU@gnbcxd0016.gnb.st.com> (raw)
In-Reply-To: <20260526091210.20383-1-guille.rodriguez@gmail.com>
Hi,
thank you for you patch.
On Tue, May 26, 2026 at 11:12:09AM +0200, Guillermo Rodríguez wrote:
> 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
>
Acked-by: Alain Volmat <alain.volmat@foss•st.com>
Regards,
Alain
prev parent reply other threads:[~2026-06-03 8:59 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-26 9:12 [PATCH] i2c: stm32f7: fix timing computation ignoring i2c-analog-filter Guillermo Rodríguez
2026-06-03 8:59 ` Alain Volmat [this message]
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