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authorChris Metcalf <cmetcalf@tilera.com>2011-02-28 21:21:52 +0300
committerChris Metcalf <cmetcalf@tilera.com>2011-03-02 00:20:04 +0300
commit13371731487896a6ef158b1cd74297f40a3da4bb (patch)
treeaf09fca3fd8811340b373faaddcdb528f8a07669 /arch/tile/kernel/entry.S
parent04f7a3f12e10032ee3d44df1a509dbf5b2001fce (diff)
downloadlinux-13371731487896a6ef158b1cd74297f40a3da4bb.tar.xz
arch/tile: fix __ndelay etc to work better
The current implementations of __ndelay and __udelay call a hypervisor service to delay, but the hypervisor service isn't actually implemented very well, and the consensus is that Linux should handle figuring this out natively and not use a hypervisor service. By converting nanoseconds to cycles, and then spinning until the cycle counter reaches the desired cycle, we get several benefits: first, we are sensitive to the actual clock speed; second, we use less power by issuing a slow SPR read once every six cycles while we delay; and third, we properly handle the case of an interrupt by exiting at the target time rather than after some number of cycles. Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
Diffstat (limited to 'arch/tile/kernel/entry.S')
-rw-r--r--arch/tile/kernel/entry.S6
1 files changed, 0 insertions, 6 deletions
diff --git a/arch/tile/kernel/entry.S b/arch/tile/kernel/entry.S
index fd8dc42abdcb..c3aa0676ed06 100644
--- a/arch/tile/kernel/entry.S
+++ b/arch/tile/kernel/entry.S
@@ -38,12 +38,6 @@ STD_ENTRY(kernel_execve)
jrp lr
STD_ENDPROC(kernel_execve)
-/* Delay a fixed number of cycles. */
-STD_ENTRY(__delay)
- { addi r0, r0, -1; bnzt r0, . }
- jrp lr
- STD_ENDPROC(__delay)
-
/*
* We don't run this function directly, but instead copy it to a page
* we map into every user process. See vdso_setup().