From: timur@tabi.org (Timur Tabi) Date: Wed, 31 Jul 2013 19:13:02 -0500 Subject: [PATCH 2/2] Convert PowerPC macro spin_event_timeout() to architecture independent macro In-Reply-To: <51F9A5FE.8030608@codeaurora.org> References: <1375187900-17582-1-git-send-email-B44344@freescale.com> <1375187900-17582-3-git-send-email-B44344@freescale.com> <20130731071630.GI8868@codeaurora.org> <51F9A5FE.8030608@codeaurora.org> Message-ID: <51F9A80E.5010307@tabi.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 07/31/2013 07:04 PM, Stephen Boyd wrote: > If it yields why are we using udelay? Why not usleep_range()? It would > be useful to have a variant that worked in interrupt context and it > looked like that was almost possible. I've never heard of usleep_range() before, so I don't know if it applies. Apparently, udelay() includes its own call to cpu_relax(). Is it possible that cpu_relax() is a "lightweight" yield, compared to sleeping? FYI, you might want to look at the code reviews for spin_event_timeout() on the linuxppc-dev mailing list, back in March 2009. -- -- Timur Tabi