> On Jun 3, 2018, at 7:30 AM, Thor Lancelot Simon <t...@panix.com> wrote:
>
> On Sat, Jun 02, 2018 at 03:51:07PM -0700, Jason Thorpe wrote:
>>
>>> On Jun 2, 2018, at 2:07 PM, Paul Goyette <p...@whooppee.com> wrote:
>>>
>>> There's the "minimal-functionality" controller that sits on the "system
>>> management PCI bus" and driven by the imc/imcsmb driver.
>>
>>
>> OMG, what a dumpster fire. Geez, if they were going to to for minimal
>> functionality, why even bother with dumb logic like that?? A pair of GPIO
>> pins would have been better!
>
> I have a dumb suggestion.
>
> Would we avoid, in the end, pain and suffering if we didn't treat this
> controller (or controllers like it) as i2c controllers, and just provided
> alternate attachements for the leaf drivers?
>
> Then we'd be free to use more sophisticated methods with "real" i2c
> controllers, and only do potentially invasive things when we found a
> nasty pseudo-i2c one.
Actually, I am thinking more of a set of properties that control the behavior
of the generic i2c code:
— i2c-indirect-probe-strategy — We’ll let the i2c code default to
“smbus_quick_write”, and this property can override with “smbus_receive_byte”
or “none”. If “none”, then we skip the probe entirely as we do now, but of
course run the risk of device ghosting.
— i2c-indirect-device-whitelist — For a case like the Intel CPU imc, it can
provide an array of device names that it can safely handle. This seems
reasonable considering it’s a specialized controller anyway that’s designed
specifically to talk to memory SPD EEPROMs. Think of this as almost a hybrid
of direct and indirect … “this is what will be here, but we don’t know if it
actually is”. In this scenario, a driver like spdmem would have to do do the
heavy lifting to do the actual presence-detect (which it already does, in fact).
Boy, I really would like a way to get access to the new device_t between
config_found and when it calls ca_attach for the device… right now,
device_register is the only hook we have for attaching properties to a new
device.
-- thorpej
