From: Doug Anderson <dianders@chromium.org>
To: Wolfram Sang <wsa@the-dreams.de>
Cc: olof@lixom.net, Doug Anderson <dianders@chromium.org>,
robh+dt@kernel.org, pawel.moll@arm.com, mark.rutland@arm.com,
ijc+devicetree@hellion.org.uk, galak@codeaurora.org,
rdunlap@infradead.org, devicetree@vger.kernel.org,
linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH] i2c: mux: Add more warnings to i2c-arb-gpio-challenge docs
Date: Tue, 29 Apr 2014 10:30:51 -0700 [thread overview]
Message-ID: <1398792651-27115-1-git-send-email-dianders@chromium.org> (raw)
This adds some more warnings to the i2c-arb-gpio-challenge docs to
help encourage people not to use it in their designs unless they have
no choice.
Signed-off-by: Doug Anderson <dianders@chromium.org>
---
Documentation/devicetree/bindings/i2c/i2c-arb-gpio-challenge.txt | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/Documentation/devicetree/bindings/i2c/i2c-arb-gpio-challenge.txt b/Documentation/devicetree/bindings/i2c/i2c-arb-gpio-challenge.txt
index 1ac8ea8..bfeabb8 100644
--- a/Documentation/devicetree/bindings/i2c/i2c-arb-gpio-challenge.txt
+++ b/Documentation/devicetree/bindings/i2c/i2c-arb-gpio-challenge.txt
@@ -8,6 +8,12 @@ the standard I2C multi-master rules. Using GPIOs is generally useful in
the case where there is a device on the bus that has errata and/or bugs
that makes standard multimaster mode not feasible.
+Note that this scheme works well enough but has some downsides:
+* It is nonstandard (not using standard I2C multimaster)
+* Having two masters on a bus in general makes it relatively hard to debug
+ problems (hard to tell if i2c issues were caused by one master, another, or
+ some device on the bus).
+
Algorithm:
--
1.9.1.423.g4596e3a
next reply other threads:[~2014-04-29 17:30 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-04-29 17:30 Doug Anderson [this message]
2014-05-21 10:29 ` [PATCH] i2c: mux: Add more warnings to i2c-arb-gpio-challenge docs Wolfram Sang
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