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From: Loic Poulain <loic.poulain@oss.qualcomm.com>
To: Robert Foss <rfoss@kernel.org>,
	Andi Shyti <andi.shyti@kernel.org>,
	Wolfram Sang <wsa+renesas@sang-engineering.com>,
	Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>,
	Luca Weiss <luca@lucaweiss.eu>
Cc: linux-i2c@vger.kernel.org, linux-arm-msm@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	Loic Poulain <loic.poulain@oss.qualcomm.com>
Subject: [PATCH 0/3] i2c: qcom-cci: Fix CCI clock rate enforcement
Date: Tue, 21 Jul 2026 16:58:18 +0200	[thread overview]
Message-ID: <20260721-cci-clk-fix-v1-0-5eae78700da8@oss.qualcomm.com> (raw)

The CCI hw_params timing values (thigh, tlow, etc.) are expressed in
clock ticks and were calibrated for a specific CCI clock frequency per
hardware variant (19.2 MHz for v1/v1.5/msm8953, 37.5 MHz for v2).
Running at the wrong frequency causes incorrect I2C timings that may
violate the I2C specification.

A previous series removed the cci_clk_rate field and the associated
warning from the driver on the grounds that the warning was noisy and
the rate was already set via assigned-clock-rates in the DT. However,
enforcing a clock frequency configuration through DT is fragile and not
the right approach, the driver owns the hw_params and should own the
clock rate too.

This series reverts the removal of cci_clk_rate, fixes the missing rate
for the msm8953 variant (added after the field was removed), and
replaces the passive warn-only approach with an active clk_set_rate()
at probe time, retaining the warning for cases where the rate cannot be
applied.

Signed-off-by: Loic Poulain <loic.poulain@oss.qualcomm.com>
---
Loic Poulain (3):
      Revert "i2c: qcom-cci: Remove unused struct member cci_clk_rate"
      i2c: qcom-cci: Add missing cci_clk_rate for msm8953
      i2c: qcom-cci: Fix CCI clock rate enforcement

 drivers/i2c/busses/i2c-qcom-cci.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)
---
base-commit: fce2dfa773ced15f27dd27cd0b482a7473cdcf2a
change-id: 20260721-cci-clk-fix-fe145b2acfa7

Best regards,
-- 
Loic Poulain <loic.poulain@oss.qualcomm.com>


             reply	other threads:[~2026-07-21 14:58 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-07-21 14:58 Loic Poulain [this message]
2026-07-21 14:58 ` [PATCH 1/3] Revert "i2c: qcom-cci: Remove unused struct member cci_clk_rate" Loic Poulain
2026-07-24 22:57   ` Andi Shyti
2026-07-25  5:41     ` Vladimir Zapolskiy
2026-07-25  8:40     ` Vladimir Zapolskiy
2026-07-26 15:08       ` Andi Shyti
2026-07-21 14:58 ` [PATCH 2/3] i2c: qcom-cci: Add missing cci_clk_rate for msm8953 Loic Poulain
2026-07-25  6:42   ` Vladimir Zapolskiy
2026-07-25  8:36   ` Vladimir Zapolskiy
2026-07-25 13:06     ` Loic Poulain
2026-07-25 14:19       ` Vladimir Zapolskiy
2026-07-21 14:58 ` [PATCH 3/3] i2c: qcom-cci: Fix CCI clock rate enforcement Loic Poulain
2026-07-21 15:07   ` Konrad Dybcio
2026-07-21 15:41     ` Loic Poulain
2026-07-21 17:01       ` Konrad Dybcio
2026-07-23  3:04 ` [PATCH 0/3] " Wenmeng Liu

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