On 3/8/19 2:40 PM, Simon Horman wrote:
> On Mon, Mar 04, 2019 at 12:13:49PM +0100, Wolfram Sang wrote:
>> On Mon, Mar 04, 2019 at 11:59:48AM +0100, Marek Vasut wrote:
>>> On 3/4/19 11:57 AM, Wolfram Sang wrote:
>>>>
>>>>>> Add DA9063 PMIC node to the I2C bus.
>>>>>>
>>>>>> Signed-off-by: Marek Vasut <marek.vasut+renesas@xxxxxxxxx>
>>>>>
>>>>> Thanks for your patch!
>>>>>
>>>>> Reviewed-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
>>>>
>>>> Thanks for CCing me, I didn't get and missed the original patch.
>>>>
>>>>>> +++ b/arch/arm/boot/dts/r8a7794-alt.dts
>>>>>> @@ -377,6 +377,27 @@
>>>>>> pinctrl-names = "i2c-exio4";
>>>>>> };
>>>>>>
>>>>>> +&i2c7 {
>>>>>> + status = "okay";
>>>>>> + clock-frequency = <100000>;
>>>>>
>>>>> According to the DA9063 datasheet, the PMIC supports up to 400 kHz.
>>>>> It looks like there are no other devices on the bus.
>>>>>
>>>>> Wolfram, what's your stance on this?
>>>>
>>>> Yes, please. I thought this was standard on Gen2 IIC_DVFS busses, but
>>>> seems not. Probably it slipped through the cracks.
>>>
>>> Do we want to update all of the other boards too ?
>>>
>>> I'd be cautious about the DVFS I2C, running faster while talking to the
>>> PMIC and reading/writing a few registers brings little benefit, while
>>> the signal integrity might be impacted.
>>
>> Can be argued. I think if we would apply some testing on top of this
>> change, we will find that it will work. But we would in deed need this
>> testing as verification, and this is not our top priority project. But
>> if someone feels like running some i2c dumping over night, well,
>> why not..
>
> Thanks,
>
> I've applied this patch for v5.2.
> We can do a sweep of frequency updates as a follow-up if we decide
> that is the right way to go.
Do we really want to speed up the PMIC I2C bus ? What are the pros
(none?) and cons (might be unstable) ?
--
Best regards,
Marek Vasut
