linux-kernel - [PATCH] i2c: qcom-geni: fix I2C frequency table to achieve accurate bus rates

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Message-Id: <20250513-i2c-bus-freq-v1-1-9a333ad5757f@oss.qualcomm.com>
Date: Tue, 13 May 2025 16:38:33 +0530
From: Kathiravan Thirumoorthy <kathiravan.thirumoorthy@....qualcomm.com>
To: Mukesh Kumar Savaliya <quic_msavaliy@...cinc.com>,
        Viken Dadhaniya <quic_vdadhani@...cinc.com>,
        Andi Shyti <andi.shyti@...nel.org>,
        Manikanta Mylavarapu <quic_mmanikan@...cinc.com>,
        Bjorn Andersson <andersson@...nel.org>
Cc: linux-i2c@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org, stable@...nel.org,
        Kathiravan Thirumoorthy <kathiravan.thirumoorthy@....qualcomm.com>
Subject: [PATCH] i2c: qcom-geni: fix I2C frequency table to achieve
 accurate bus rates

Update the I2C frequency table to match the recommended values
specified in the I2C hardware programming guide. In the current IPQ5424
configuration where 32MHz is the source clock, the I2C bus frequencies do
not meet expectations—for instance, 363KHz is achieved instead of the
expected 400KHz.

Cc: stable@...nel.org
Fixes: 506bb2ab0075 ("i2c: qcom-geni: Support systems with 32MHz serial engine clock")
Signed-off-by: Kathiravan Thirumoorthy <kathiravan.thirumoorthy@....qualcomm.com>
---
 drivers/i2c/busses/i2c-qcom-geni.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/i2c/busses/i2c-qcom-geni.c b/drivers/i2c/busses/i2c-qcom-geni.c
index ccea575fb7838db864ca4a2b21ebb3835b2567b2..2fec7b44bfc1baec68e321a9f57de4156120919b 100644
--- a/drivers/i2c/busses/i2c-qcom-geni.c
+++ b/drivers/i2c/busses/i2c-qcom-geni.c
@@ -155,9 +155,9 @@ static const struct geni_i2c_clk_fld geni_i2c_clk_map_19p2mhz[] = {
 
 /* source_clock = 32 MHz */
 static const struct geni_i2c_clk_fld geni_i2c_clk_map_32mhz[] = {
-	{ I2C_MAX_STANDARD_MODE_FREQ, 8, 14, 18, 40 },
-	{ I2C_MAX_FAST_MODE_FREQ, 4,  3, 11, 20 },
-	{ I2C_MAX_FAST_MODE_PLUS_FREQ, 2, 3,  6, 15 },
+	{ I2C_MAX_STANDARD_MODE_FREQ, 8, 14, 18, 38 },
+	{ I2C_MAX_FAST_MODE_FREQ, 4,  3, 9, 19 },
+	{ I2C_MAX_FAST_MODE_PLUS_FREQ, 2, 3, 5, 15 },
 	{}
 };
 

---
base-commit: edef457004774e598fc4c1b7d1d4f0bcd9d0bb30
change-id: 20250513-i2c-bus-freq-ac46343869a4

Best regards,
-- 
Kathiravan Thirumoorthy <kathiravan.thirumoorthy@....qualcomm.com>