From mboxrd@z Thu Jan 1 00:00:00 1970 From: skannan@codeaurora.org (Saravana Kannan) Date: Thu, 27 May 2010 17:41:14 -0700 Subject: [PATCH V2] [ARM] Add ARCH_PROVIDES_UDELAY config option In-Reply-To: <20100521220653.GL11042@n2100.arm.linux.org.uk> References: <1272654736-28837-1-git-send-email-ccross@android.com> <87d3xgd20n.fsf@deeprootsystems.com> <20100501100148.GE12172@n2100.arm.linux.org.uk> <4BF702CC.5000401@codeaurora.org> <20100521220653.GL11042@n2100.arm.linux.org.uk> Message-ID: <4BFF112A.2060700@codeaurora.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Russell King - ARM Linux wrote: > My point is not specific to sched_clock, but to counters which on ARM > are 99.9% always memory mapped, and therefore inaccessible during the > very early kernel boot. sched_clock was merely an illustration of the > problem. Do you know any code which uses udelay that early? I can't imagine any non-driver code using udelay. If it's just drivers using udelay, then they need IO mapping to have been completed for the device register access to work and hence udelay won't have any problems. -Saravana