From: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
To: Loic Poulain <loic.poulain@oss.qualcomm.com>,
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, vladimir.zapolskiy@linaro.org,
konradybcio@kernel.org, stephan.gerhold@linaro.org
Subject: Re: [PATCH v4 1/5] i2c: qcom-cci: Switch msm8953 to the CCI v2 timing/rate config
Date: Tue, 18 Aug 2026 13:54:53 +0200 [thread overview]
Message-ID: <19e93687-eccf-4aed-8d84-20c2389696ef@oss.qualcomm.com> (raw)
In-Reply-To: <20260801-cci-clk-fix-v4-1-e1d80da54e01@oss.qualcomm.com>
On 8/1/26 10:10 PM, Loic Poulain wrote:
> The msm8953 CCI timing table is internally inconsistent. Its Standard
> and Fast timings match v1/v1.5, which are calibrated for a 19.2 MHz CCI
> clock, but its Fast+ timings are essentially the v2 values, which are
> calibrated for 37.5 MHz. Since all masters share a single CCI clock,
> no single rate can satisfy all three modes with the current table, and
> the DT assigns 19.2 MHz, so Fast+ timings are wrong.
>
> The msm8953 CCI is the same hardware version as msm8996/sdm630, which
> already use the cci_v2_data config (37.5 MHz). 37.5 MHz is supported by
> the msm8953 CCI RCG, so reuse cci_v2_data for msm8953 as well and drop
> the redundant, inconsistent standalone table. This makes all three I2C
> modes self-consistent under a single clock rate.
>
> Note this requires the CCI clock to run at 37.5 MHz, the driver selects
> and enforces the proper rate in following patches.
>
> Signed-off-by: Loic Poulain <loic.poulain@oss.qualcomm.com>
> ---
Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
Konrad
next prev parent reply other threads:[~2026-08-18 11:55 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-01 20:10 [PATCH v4 0/5] i2c: qcom-cci: Enforce the required CCI clock rate Loic Poulain
2026-08-01 20:10 ` [PATCH v4 1/5] i2c: qcom-cci: Switch msm8953 to the CCI v2 timing/rate config Loic Poulain
2026-08-18 11:54 ` Konrad Dybcio [this message]
2026-08-01 20:10 ` [PATCH v4 2/5] i2c: qcom-cci: Support per-mode CCI clock rates Loic Poulain
2026-08-18 11:59 ` Konrad Dybcio
2026-08-01 20:10 ` [PATCH v4 3/5] i2c: qcom-cci: Add 19.2 MHz timings for the v2 CCI Loic Poulain
2026-08-18 12:06 ` Konrad Dybcio
2026-08-01 20:10 ` [PATCH v4 4/5] i2c: qcom-cci: Share the timing table across CCI revisions Loic Poulain
2026-08-18 12:07 ` Konrad Dybcio
2026-08-01 20:10 ` [PATCH v4 5/5] i2c: qcom-cci: Enforce the required CCI clock rate Loic Poulain
2026-08-18 12:16 ` Konrad Dybcio
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