Re: [PATCH 10/10] mtd: spi-nor: aspeed: optimize read mode

Marek Vasut
2017-04-14T21:51:55Z

On 04/14/2017 11:40 PM, Benjamin Herrenschmidt wrote:
> On Fri, 2017-04-14 at 18:18 +0200, Marek Vasut wrote:
>>> Here is a proposal. We could activate this algo using a property such
>>> as :
>>>
>>> "speed-mode" = "freq" or "auto-adjust"
>>>
>>> How's that ?
>>
>> Thinking about it a bit more, I think having a module parameter is the
>> right approach here ... or maybe compile-time switch. This shouldn't be
>> in DT as it's not HW property.
>
> Strong disagreement here :-)
>
> DT is not *strictly* HW properties. Never was despite what some
> fanatics around might say :-) Its also platform properties and can
> include policies.

/me grabs popcorn ... :-)

> We put things like UART speeds in there, MAC addresses, etc...

UART speeds or UART max/allowed speeds ? That's basically HW property
since flaky HW might not allow all sorts of UART speed options. MAC
address is a HW property.

> it makes
> sense to put calibration info and in this case, request to perform SW
> calibration.

That's a hard question and I don't have the right answer to this.

> Module parameters are crap. They are a major pain to use, they are in
> practice only good for tweaking/experimenting.

That's correct, but then turning the calibration off would probably be
only used in such experimental setups or during HW bringup (if at all).
Based on the discussion thus far, my impression is that the preferred
and mostly used default is calibration enabled.

> Ben.
>

--
Best regards,
Marek Vasut