From: Quan Nguyen <quan@os.amperecomputing.com>
To: Jian Zhang <zhangjian.3032@bytedance.com>,
Corey Minyard <corey@minyard.net>,
openipmi-developer@lists.sourceforge.net,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3/5] ipmi: ssif_bmc: fix message desynchronization after truncated response
Date: Fri, 3 Apr 2026 14:22:41 +0700 [thread overview]
Message-ID: <61e671d8-01a8-4544-93a1-73e30f30ae7d@os.amperecomputing.com> (raw)
In-Reply-To: <20260402110435.3589408-3-zhangjian.3032@bytedance.com>
On 2/4/26 18:04, Jian Zhang wrote:
> A truncated response, caused by host power-off, or other conditions,
> can lead to message desynchronization.
>
> Raw trace data (STOP loss scenario, add state transition comment):
>
> 1. T-1: Read response phase (SSIF_RES_SENDING)
> 8271.955342 WR_RCV [03] <- Read polling cmd
> 8271.955348 RD_REQ [04] <== SSIF_RES_SENDING <- start sending response
> 8271.955436 RD_PRO [b4]
> 8271.955527 RD_PRO [00]
> 8271.955618 RD_PRO [c1]
> 8271.955707 RD_PRO [00]
> 8271.955814 RD_PRO [ad] <== SSIF_RES_SENDING <- last byte
> <- !! STOP lost (truncated response)
Honestly, I have a little concern about if there is the case. What I
think is that if there was no ACK (SCA is not pull low by Controller) on
the 9th clock pulse while Target sending data to bus. Target will
release SDA line, eventually, there will be a STOP condition and a
SLAVE_STOP event should be emitted.
- Quan
next prev parent reply other threads:[~2026-04-03 7:22 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-02 11:04 [PATCH 1/5] ipmi: ssif_bmc: cancel response timer on remove Jian Zhang
2026-04-02 11:04 ` [PATCH 2/5] ipmi: ssif_bmc: fix missing check for copy_to_user() partial failure Jian Zhang
2026-04-02 11:04 ` [PATCH 3/5] ipmi: ssif_bmc: fix message desynchronization after truncated response Jian Zhang
2026-04-03 7:22 ` Quan Nguyen [this message]
2026-04-03 8:12 ` Jian Zhang
2026-04-02 11:04 ` [PATCH 4/5] ipmi: ssif_bmc: change log level to dbg in irq callback Jian Zhang
2026-04-02 11:04 ` [PATCH 5/5] ipmi: ssif_bmc: add unit test for state machine Jian Zhang
2026-04-02 15:42 ` [Openipmi-developer] [PATCH 1/5] ipmi: ssif_bmc: cancel response timer on remove Corey Minyard
2026-04-03 7:23 ` Quan Nguyen
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