[PATCH 1/3] ipmi/bt-bmc: change compatible node to 'aspeed,ast2400-ibt-bmc'

Cédric Le Goater clg at kaod.org
Wed Nov 2 07:28:01 PDT 2016

On 11/02/2016 02:56 PM, Joel Stanley wrote:
> On Wed, Nov 2, 2016 at 11:45 PM, Arnd Bergmann <arnd at arndb.de> wrote:
>> On Wednesday 02 November 2016, Cédric Le Goater wrote:
>>> The Aspeed SoCs have two BT interfaces : one is IPMI compliant and the
>>> other is H8S/2168 compliant.
>>> The current ipmi/bt-bmc driver implements the IPMI version and we
>>> should reflect its nature in the compatible node name using
>>> 'aspeed,ast2400-ibt-bmc' instead of 'aspeed,ast2400-bt-bmc'. The
>>> latter should be used for a H8S interface driver if it is implemented
>>> one day.
>>> Signed-off-by: Cédric Le Goater <clg at kaod.org>
>> We generally try to avoid changing the compatible strings after the
>> fact, but it's probably ok in this case.

As the device tree changes are not merged yet, we thought we had some 
more time to fine tune the naming. 
>> I don't understand who decides which of the two interfaces is used:
>> is it the same register set that can be driven by either one or the
>> other driver, or do you expect to have two drivers that can both
>> be active in the same system and talk to different hardware once
>> you get there?
> It's the second case. The H8S BT has a different register layout so it
> would require a different driver.

> We don't yet have a driver for the other BT device, but there was
> recent talk of using it as an alternate (non-ipmi channel) between the
> BMC and the host. Before that discussion I wasn't aware that the H8S
> BT existed. I suggested we fix this up before it hits a final release.
> Cédric, do you think ast2400-ibt-bmc or ast2400-ipmi-bt-bmc does a
> better job of describing the hardware here?

The specs refer to the two interfaces as BT (non IPMI) and iBT (IPMI). 
I think we can keep the same naming.

> While we're modifying the binding, should we add a compat string for
> the ast2500?

Well, if the change in this patch is fine for all, may be we can add 
the ast2500 compat string in a followup patch ?



> Cheers,
> Joel
>> If the first one of these is true, it seems a little awkward to
>> use the DT compatible string to decide which driver to use rather
>> than making the decision in the OS.
>>         Arnd

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