[PATCH] arm64: dts: monaco: Fix CSI I2C controllers default bus frequency

[PATCH] arm64: dts: monaco: Fix CSI I2C controllers default bus frequency

[Hans de Goede]

1 MHz is quite fast for an I2C bus and not necessarly reliable, change this
to 400 KHz which is a more reasonable default.

Signed-off-by: Hans de Goede <johannes.goede@oss.qualcomm.com>
---
 arch/arm64/boot/dts/qcom/monaco.dtsi | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/arch/arm64/boot/dts/qcom/monaco.dtsi b/arch/arm64/boot/dts/qcom/monaco.dtsi
index a22be507ed9c..d3b59b9e84e6 100644
--- a/arch/arm64/boot/dts/qcom/monaco.dtsi
+++ b/arch/arm64/boot/dts/qcom/monaco.dtsi
@@ -5472,14 +5472,14 @@ cci0: cci@ac13000 {
 
 			cci0_i2c0: i2c-bus@0 {
 				reg = <0>;
-				clock-frequency = <1000000>;
+				clock-frequency = <400000>;
 				#address-cells = <1>;
 				#size-cells = <0>;
 			};
 
 			cci0_i2c1: i2c-bus@1 {
 				reg = <1>;
-				clock-frequency = <1000000>;
+				clock-frequency = <400000>;
 				#address-cells = <1>;
 				#size-cells = <0>;
 			};
@@ -5509,14 +5509,14 @@ cci1: cci@ac14000 {
 
 			cci1_i2c0: i2c-bus@0 {
 				reg = <0>;
-				clock-frequency = <1000000>;
+				clock-frequency = <400000>;
 				#address-cells = <1>;
 				#size-cells = <0>;
 			};
 
 			cci1_i2c1: i2c-bus@1 {
 				reg = <1>;
-				clock-frequency = <1000000>;
+				clock-frequency = <400000>;
 				#address-cells = <1>;
 				#size-cells = <0>;
 			};
@@ -5546,14 +5546,14 @@ cci2: cci@ac15000 {
 
 			cci2_i2c0: i2c-bus@0 {
 				reg = <0>;
-				clock-frequency = <1000000>;
+				clock-frequency = <400000>;
 				#address-cells = <1>;
 				#size-cells = <0>;
 			};
 
 			cci2_i2c1: i2c-bus@1 {
 				reg = <1>;
-				clock-frequency = <1000000>;
+				clock-frequency = <400000>;
 				#address-cells = <1>;
 				#size-cells = <0>;
 			};
-- 
2.55.0

Re: [PATCH] arm64: dts: monaco: Fix CSI I2C controllers default bus frequency

[Konrad Dybcio]

On 7/23/26 1:48 PM, Hans de Goede wrote:
> 1 MHz is quite fast for an I2C bus and not necessarly reliable, change this
> to 400 KHz which is a more reasonable default.
> 
> Signed-off-by: Hans de Goede <johannes.goede@oss.qualcomm.com>


I guess this is a question of what's more common among client
devices. I assume you have some that aren't happy with 1 MHz?

Konrad

Re: [PATCH] arm64: dts: monaco: Fix CSI I2C controllers default bus frequency

[Hans de Goede]

Hi,

On 24-Jul-26 1:42 PM, Konrad Dybcio wrote:
> On 7/23/26 1:48 PM, Hans de Goede wrote:
>> 1 MHz is quite fast for an I2C bus and not necessarly reliable, change this
>> to 400 KHz which is a more reasonable default.
>>
>> Signed-off-by: Hans de Goede <johannes.goede@oss.qualcomm.com>
> 
> 
> I guess this is a question of what's more common among client
> devices. I assume you have some that aren't happy with 1 MHz?

Looking at ACPI tables for many x86 devices 400 KHz is the standard,
with some devices going down to 100 KHz. 1 MHz is pretty much
unheard off.

Note the official I2C spec is limited to 100 KHz anything faster then
that is an extension.

My specific reason for submitting this patch is imx219 sensors on
Mona sometimes failing to initialize at 1MHz which is kinda to
be expected when going for 10x the I2C specification max value.

Regards,

Hans

Re: [PATCH] arm64: dts: monaco: Fix CSI I2C controllers default bus frequency

[Konrad Dybcio]

On 7/24/26 4:22 PM, Hans de Goede wrote:
> Hi,
> 
> On 24-Jul-26 1:42 PM, Konrad Dybcio wrote:
>> On 7/23/26 1:48 PM, Hans de Goede wrote:
>>> 1 MHz is quite fast for an I2C bus and not necessarly reliable, change this
>>> to 400 KHz which is a more reasonable default.
>>>
>>> Signed-off-by: Hans de Goede <johannes.goede@oss.qualcomm.com>
>>
>>
>> I guess this is a question of what's more common among client
>> devices. I assume you have some that aren't happy with 1 MHz?
> 
> Looking at ACPI tables for many x86 devices 400 KHz is the standard,
> with some devices going down to 100 KHz. 1 MHz is pretty much
> unheard off.
> 
> Note the official I2C spec is limited to 100 KHz anything faster then
> that is an extension.
> 
> My specific reason for submitting this patch is imx219 sensors on
> Mona sometimes failing to initialize at 1MHz which is kinda to
> be expected when going for 10x the I2C specification max value.

FWIW I don't mind this patch but wanted to know more background

Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>

Konrad