linux-kernel - Re: [PATCH] ipmi: kcs: Poll OBF briefly to reduce OBE latency

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Message-Id: <c992be3d-2002-44e3-8bee-9ded84145ad1@app.fastmail.com>
Date:   Thu, 06 Oct 2022 13:38:30 +1030
From:   "Andrew Jeffery" <andrew@...id.au>
To:     "Corey Minyard" <minyard@....org>
Cc:     openipmi-developer@...ts.sourceforge.net,
        linux-aspeed@...ts.ozlabs.org, openbmc@...ts.ozlabs.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] ipmi: kcs: Poll OBF briefly to reduce OBE latency



On Thu, 6 Oct 2022, at 10:24, Corey Minyard wrote:
> On Thu, Oct 06, 2022 at 09:42:57AM +1030, Andrew Jeffery wrote:
>> Hi Corey,
>> 
>> On Sat, 13 Aug 2022, at 00:17, Andrew Jeffery wrote:
>> > The ASPEED KCS devices don't provide a BMC-side interrupt for the host
>> > reading the output data register (ODR). The act of the host reading ODR
>> > clears the output buffer full (OBF) flag in the status register (STR),
>> > informing the BMC it can transmit a subsequent byte.
>> >
>> > On the BMC side the KCS client must enable the OBE event *and* perform a
>> > subsequent read of STR anyway to avoid races - the polling provides a
>> > window for the host to read ODR if data was freshly written while
>> > minimising BMC-side latency.
>> 
>> Just wondering whether you're happy to pick this one up? I haven't seen 
>> it hit the IPMI tree yet.
>
> Sorry.  It's in my tree for 6.2 right now.

Thanks!

>
> I can't push it up to for-next until 6.1-rc1 comes out.
>

No worries, just wanted to make sure it didn't fall through the cracks 
:)

Andrew