[PATCH 1/3] misc: Add Aspeed BT IPMI host driver

[Corey Minyard]

On 09/12/2016 02:15 PM, Arnd Bergmann wrote:
> On Monday, September 12, 2016 1:55:40 PM CEST Corey Minyard wrote:
>> On 09/02/2016 08:22 AM, Cédric Le Goater wrote:
>>> Hello,
>>>
>>> Adding Corey in cc: . I guess I should have done that in the first place.
>> Yes, probably so.  I've been travelling and didn't see it on the mailing
>> lists until now.
>>
>> There is already a BT driver in the kernel, in drivers/char/ipmi, why
>> won't that work?
> The new driver is the host side (running on the BMC), the existing one
> is the client (running on the PC).
>
> 	Arnd

Ok, that's not really clear from the documentation or the Kconfig.
In the IPMI spec the "host" side is the computer side, not the BMC
side.  Like:

    11.6.1 BT Host Interface Registers
    The Host BT interface provides an independent set of registers and
    interrupts to allow the Host driver to
    communicate with the baseboard management controller without
    conflicting with the O/S ACPI driver.

In light of that, this should probably be named the bt-bmc driver.

I haven't reviewed this in detail, but I'm ok with putting it in
drivers/char/ipmi.  The state machine part looks reasonably
generic.  The configuration part isn't, but that could be split
out later if necessary.

The biggest thing I don't like is the byte at a time interfaces
from userspace.  That seems fairly inefficient if the system
does extra work for each userspace access.  IIRC some
systems do and some don't.

-corey

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