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authorAndres Salomon <dilinger@queued.net>2010-12-02 14:31:17 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2010-12-02 14:51:15 -0800
commit853ff88324a248a9f5da6e110850223db353ec07 (patch)
tree6e48a44c672123d8671af2bffedfefee68133151 /include
parent238af8751f64a75f8b638193353b1c31ea32e738 (diff)
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cs5535-gpio: apply CS5536 errata workaround for GPIOs
The AMD Geode CS5536 Companion Device Silicon Revision B1 Specification Update mentions the follow as issue #36: "Atomic write transactions to the atomic GPIO High Bank Feature Bit registers should only affect the bits selected [...]" "after Suspend, an atomic write transaction [...] will clear all non-selected bits of the accessed register." In other words, writing to the high bank for a single GPIO bit will clear every other GPIO bit (but only sometimes after a suspend). The workaround described is obvious and simple; do a read-modify-write. This patch does that, and documents why we're doing it. Signed-off-by: Andres Salomon <dilinger@queued.net> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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