[PATCH 2/2] arm64: dts: imx8mm: Add i.MX8M Mini Toradex Verdin based Menlo board

[Marek Vasut]

On 4/8/22 17:29, Tim Harvey wrote:
> On Fri, Apr 8, 2022 at 2:05 AM Francesco Dolcini
> <francesco.dolcini at toradex.com> wrote:
>>
>> On Fri, Apr 08, 2022 at 09:56:09AM +0200, Marcel Ziswiler wrote:
>>> On Fri, 2022-04-08 at 08:46 +0200, Francesco Dolcini wrote:
>>>> On Thu, Apr 07, 2022 at 10:24:56PM +0200, Marek Vasut wrote:
>>>>> +
>>>>> +&i2c1 {
>>>>> +       /* IMX8MM ERRATA e7805 -- I2C is limited to 384 kHz due to SoC bug */
>>>>> +       clock-frequency = <100000>;
>>>> should this and the related changes in the other i2c nodes done in the
>>>> verdin.dtsi? Marcel? (errata is here:
>>>> https://www.nxp.com/docs/en/errata/IMX8MDQLQ_1N14W.pdf)
>>>
>>> Hehe, good catch. Yeah, we probably should move this one into imx8mm-verdin.dtsi instead. On the other hand, it
>>> won't hurt doing it twice resp. this one will always override it like that.
>>>
>>> Anyway, looks like NXP has not fixed this and is re-using the exact same I2C IP with the same errata (;-p).
>>
>> It looks like even i.MX7 is affected, and NXP has a quirk in the
>> i2c-imx driver [0]
>>
>> [0] https://source.codeaurora.org/external/imx/linux-imx/commit/drivers/i2c/busses/i2c-imx.c?h=lf-5.15.y&id=493b3892ee156af529796641889ca19b971735d2
>>
>> Francesco
> 
> Francesco and Marek,
> 
> Interesting - I've never noticed this errata.
> 
> I don't see mention of it in the imx8mm-evk which sets the busses to
> 400khz, and all the other verdin I2C busses are set to 400khz as well.
> 
> Should we address this in the i2c driver in U-Boot (and Linux)
> instead? Otherwise, I think all of us board maintainers should be
> moving the i2c clock to 100kHz. Its not clear to me what I2C slaves
> may be affected by this issue.... perhaps maintainers are only
> concerned with things that go off-board?

320 kHz or 100 kHz divide down nicely, so I use either of those 
depending on whether I need faster I2C or not.

I2C IMX Linux driver patch is posted here:
https://patchwork.ozlabs.org/project/linux-i2c/patch/20220408171524.73551-1-marex@denx.de/