[PATCH v2 0/3] Add Aspeed SSIF BMC driver
minyard at acm.org
Thu Apr 8 00:28:28 AEST 2021
On Wed, Apr 07, 2021 at 08:09:50PM +0700, Quan Nguyen wrote:
> Hi Corey,
> Thank you for reviewing
> I'll put my respond inline below.
> On 02/04/2021 21:21, Corey Minyard wrote:
> > On Tue, Mar 30, 2021 at 09:10:26PM +0700, Quan Nguyen wrote:
> > > This series add support for the Aspeed specific SSIF BMC driver which
> > > is to perform in-band IPMI communication with the host in management
> > > (BMC) side.
> > I don't have any specific feedback for this, but I'm wondering if it's
> > really necessary.
> > Why can't the BMC just open the I2C device and use it? Is there any
> > functionality that this provides that cannot be accomplished from
> > userland access to the I2C device? I don't see any.
> > If it tied into some existing framework to give abstract access to a BMC
> > slave side interface, I'd be ok with this. But I don't see that.
> The SSIF at the BMC side acts as an I2C slave and we think that the kernel
> driver is unavoidable to handle the I2c slave events
> And to make it works with existing OpenBMC IPMI stack, a userspace part,
> ssifbridge, is needed (https://github.com/openbmc/ssifbridge). This
> ssifbridge is to connect this driver with the OpenBMC IPMI stack so the IPMI
> stack can communicate via SSIF channel in similar way that was implemented
> with BT and KCS (ie: btbridge/kcsbridge and its corespondent kernel drivers
> (https://github.com/openbmc/btbridge and
Dang, I don't know why there's not a generic userland interface for
the slave. And I've made this mistake before :(.
Anyway, you are right, you need a driver. I'll review.
> > Unless there is a big need to have this in the kernel, I'm against
> > including this and would suggest you do all this work in userland.
> > Perhaps write a library. Sorry, but I'm trying to do my part to reduce
> > unnecessary things in the kernel.
> > Thanks,
> > -corey
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