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SubjectRe: [PATCH v1 3/6] ARM: dts: lan966x: add all flexcom usart nodes
Am 2022-03-07 12:53, schrieb Claudiu.Beznea@microchip.com:
> On 04.03.2022 13:01, Michael Walle wrote:
>> EXTERNAL EMAIL: Do not click links or open attachments unless you know
>> the
>> content is safe
>>
>> Hi,
>>
>> thanks for the quick review.
>>
>> Am 2022-03-04 09:30, schrieb Claudiu.Beznea@microchip.com:
>>> On 03.03.2022 18:03, Michael Walle wrote:
>>>> EXTERNAL EMAIL: Do not click links or open attachments unless you
>>>> know
>>>> the content is safe
>>>>
>>>> Add all the usart nodes for the flexcom block. There was already
>>>> an usart node for the flexcom3 block. But it missed the DMA
>>>> channels.
>>>
>>> And it would be good to go though a different patch.
>>
>> sure
>>
>>>> Although the DMA channels are specified, DMA is not
>>>> enabled by default because break detection doesn't work with DMA.
>>>>
>>>> Keep the nodes disabled by default.
>>>>
>>>> Signed-off-by: Michael Walle <michael@walle.cc>
>>>> ---
>>>>  arch/arm/boot/dts/lan966x.dtsi | 55
>>>> ++++++++++++++++++++++++++++++++++
>>>>  1 file changed, 55 insertions(+)
>>>>
>>>> diff --git a/arch/arm/boot/dts/lan966x.dtsi
>>>> b/arch/arm/boot/dts/lan966x.dtsi
>>>> index a7d46a2ca058..bea69b6d2749 100644
>>>> --- a/arch/arm/boot/dts/lan966x.dtsi
>>>> +++ b/arch/arm/boot/dts/lan966x.dtsi
>>>> @@ -92,6 +92,19 @@ flx0: flexcom@e0040000 {
>>>>                         #size-cells = <1>;
>>>>                         ranges = <0x0 0xe0040000 0x800>;
>>>>                         status = "disabled";
>>>> +
>>>> +                       usart0: serial@200 {
>>>> +                               compatible =
>>>> "atmel,at91sam9260-usart";
>>>
>>> Are the usart blocks in lan966x 1:1 compatible with what is is
>>> sam9260?
>>> In
>>> case not it may worth to have a new compatible here, for lan966x,
>>> such
>>> that
>>> when new features will be implemented in usart driver for lan966x the
>>> old
>>> DT (this one) will work with the new kernel implementation.
>>
>> During my review of the inital dtsi patch, I've asked the same
>> question
>> [1]
>> and I was told they are the same.
>>
>> At least this exact usart compatible is already in this file. I was
>> under
>> the impression, that was the least controversial compatible :)
>
> OK.
>
>>
>> But you'll need to tell me if they are the same or not, I don't have
>> any clue what microchip has reused.
>
> From software point of view comparing registers should be good, as far
> as I
> can tell. All AT91 datasheet should be available. I though you have
> checked
> one against LAN966. At the moment I don't have a DS for LAN966. I'll
> find
> one and have a look.

So my train of thought was like: even if the registers are the same I
cannot be sure that it is the exact same IP and will behave the same.
Therefore, it is something only microchip can answer.

You can find the registers at
https://microchip-ung.github.io/lan9668_reginfo/reginfo_LAN9668.html

I'm not aware of any "classic" datasheet.

-michael

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