Re: [PATCH] ARM: zynq: dts: Setting default i2c clock frequency to 400kHz

[Michal Simek <michal.simek@amd.com>]

On 5/3/23 10:06, Krzysztof Kozlowski wrote:
> On 03/05/2023 10:02, Michal Simek wrote:
>>
>>
>> On 5/3/23 09:40, Krzysztof Kozlowski wrote:
>>> On 03/05/2023 09:27, Michal Simek wrote:
>>>>
>>>>
>>>> On 5/2/23 22:13, Krzysztof Kozlowski wrote:
>>>>> CAUTION: This message has originated from an External Source. Please use proper judgment and caution when opening attachments, clicking links, or responding to this email.
>>>>>
>>>>>
>>>>> On 02/05/2023 15:53, Michal Simek wrote:
>>>>>> From: Varalaxmi Bingi <varalaxmi.bingi@amd.com>
>>>>>>
>>>>>> Setting default i2c clock frequency for Zynq to maximum rate of 400kHz.
>>>>>> Current default value is 100kHz.
>>>>>>
>>>>>> Signed-off-by: Varalaxmi Bingi <varalaxmi.bingi@amd.com>
>>>>>> Signed-off-by: Michal Simek <michal.simek@amd.com>
>>>>>> ---
>>>>>>
>>>>>>     arch/arm/boot/dts/zynq-7000.dtsi | 2 ++
>>>>>>     1 file changed, 2 insertions(+)
>>>>>>
>>>>>> diff --git a/arch/arm/boot/dts/zynq-7000.dtsi b/arch/arm/boot/dts/zynq-7000.dtsi
>>>>>> index cd9931f6bcbd..a7db3f3009f2 100644
>>>>>> --- a/arch/arm/boot/dts/zynq-7000.dtsi
>>>>>> +++ b/arch/arm/boot/dts/zynq-7000.dtsi
>>>>>> @@ -149,6 +149,7 @@ i2c0: i2c@e0004000 {
>>>>>>                          clocks = <&clkc 38>;
>>>>>>                          interrupt-parent = <&intc>;
>>>>>>                          interrupts = <0 25 4>;
>>>>>> +                     clock-frequency = <400000>;
>>>>>
>>>>> I think this should be rather property of the board, because it depends
>>>>> on I2C devices, right?
>>>>
>>>> We have 15+ boards with i2c connected and from this count I am aware about only
>>>> one configuration which is not working on 400k.
>>>> It is a question if make sense to update all boards (except for 1 and not all in
>>>> kernel yet) to 400k or just say 400k is default and if there is any issue use
>>>> lower frequency.
>>>> Obviously this patch is setting up 400k as default and let "problematic" boards
>>>> to setup lower freq.
>>>> The same approach was used for modepin description.
>>>>
>>>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/arch/arm64/boot/dts/xilinx/zynqmp.dtsi?h=v6.3&id=53ba1b2bdaf7f481fdd878e9c18cd0e54081fac9
>>>>
>>>> The next point is that 100k is default in Linux but doesn't mean it is default
>>>> in other projects.
>>>>
>>>> But if you think that it must be board property I think we should setup 100k as
>>>> default in this file too to make it clear.
>>>
>>> No, if it is conscious choice, it's fine.
>>
>> Is it Ack then or you want me to extend commit message?
> 
> Ack, although you don't need my acks for your platform :)

you spell that properly. But I can. :-)

> 
> FWIW:
> 
> Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>

Thanks,
Michal

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