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Date:      Mon, 01 Jul 2019 17:14:48 +0000
From:      "Poul-Henning Kamp" <phk@phk.freebsd.dk>
To:        Warner Losh <imp@bsdimp.com>
Cc:        Ian Lepore <ian@freebsd.org>, Andriy Gapon <avg@freebsd.org>, FreeBSD Current <freebsd-current@freebsd.org>
Subject:   Re: i2c bit banging timeout for SCL
Message-ID:  <93148.1562001288@critter.freebsd.dk>
In-Reply-To: <CANCZdfoFBvmxPtnEL4GOqXTvp6Zd-xrtja4rmUO1rAcy0JdeSw@mail.gmail.com>
References:  <a3538c10-2438-a287-77db-ad390078b274@FreeBSD.org> <7e5d8a06bc2d46263262369464e9348b82263847.camel@freebsd.org> <CANCZdfoFBvmxPtnEL4GOqXTvp6Zd-xrtja4rmUO1rAcy0JdeSw@mail.gmail.com>

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--------
In message <CANCZdfoFBvmxPtnEL4GOqXTvp6Zd-xrtja4rmUO1rAcy0JdeSw@mail.gmail=
.com>, Warner Losh writes:

>The only issue, really, is that this timeout is a busy loop and there may
>be I/O bus contention introduced on these systems.

Does it have to be a busy loop for the entire duration ?

Spin for the median, timeout+poll for the rest of the time ?

-- =

Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    =

Never attribute to malice what can adequately be explained by incompetence=
.



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