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| author | Russell King <rmk@dyn-67.arm.linux.org.uk> | 2007-10-27 11:01:35 +0100 |
|---|---|---|
| committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2007-10-31 15:21:40 +0000 |
| commit | 0214f9221aa06fba35c0cd5c80641b0fcfcb1cbe (patch) | |
| tree | 7cf9e67f6acec67b7e9d84768c8fc8821f636162 /arch/arm | |
| parent | d8cb70d10a2d4e6b083b89044a68d860d0bf1eec (diff) | |
| download | linux-0214f9221aa06fba35c0cd5c80641b0fcfcb1cbe.tar.bz2 | |
[ARM] Fix FIQ issue with ARM926
Jon Eibertzon writes:
> We have noticed that the I-cache is disabled while waiting for
> interrupt in cpu_arm926_do_idle in arch/arm/mm/proc-arm926.S
> and we are curious to know why, because this causes us a great
> performance hit when executing in FIQ-handlers. Is it assumed
> here that every individual FIQ-handler re-enables the I-cache?
The I-cache disable is an errata workaround, so the solution is to
disable FIQs across the section with the I-cache disabled.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm')
| -rw-r--r-- | arch/arm/mm/proc-arm926.S | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/arm/mm/proc-arm926.S b/arch/arm/mm/proc-arm926.S index 5b80b6bdd0cb..194ef48968e6 100644 --- a/arch/arm/mm/proc-arm926.S +++ b/arch/arm/mm/proc-arm926.S @@ -105,9 +105,13 @@ ENTRY(cpu_arm926_do_idle) mrc p15, 0, r1, c1, c0, 0 @ Read control register mcr p15, 0, r0, c7, c10, 4 @ Drain write buffer bic r2, r1, #1 << 12 + mrs r3, cpsr @ Disable FIQs while Icache + orr ip, r3, #PSR_F_BIT @ is disabled + msr cpsr_c, ip mcr p15, 0, r2, c1, c0, 0 @ Disable I cache mcr p15, 0, r0, c7, c0, 4 @ Wait for interrupt mcr p15, 0, r1, c1, c0, 0 @ Restore ICache enable + msr cpsr_c, r3 @ Restore FIQ state mov pc, lr /* |