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authorPaul Burton <paul.burton@imgtec.com>2015-09-22 10:16:39 -0700
committerRalf Baechle <ralf@linux-mips.org>2015-10-26 09:49:45 +0100
commit6759657341100ce876e69946365ef91907e3015e (patch)
treebf48941916672259d52c24314c536ad5dd4955ed /arch/mips/Kconfig
parenta13c996249a5ca7635853a4e7e15033393575e46 (diff)
MIPS: Allow 24Hz timer frequency
A boundary exists beyond which the timer frequency becomes high enough that timer interrupts saturate the system and either cause it to slow to a crawl or stop functioning entirely. Where that boundary lies depends upon a number of factors such as the overhead of each interrupt and the overall speed of the CPU, but correlates strongly with the clock frequency at which the CPU runs. When running on emulators during bringup or debug of a CPU that clock frequency is very low, which results in the boundary at which the timer frequency becomes unsustainable being very low. The current minimum of 48Hz pushes against boundary in certain situations in current systems. Allow the kernel to be configured for a 24Hz timer frequency in order to avoid problems on such slow running systems. Signed-off-by: Paul Burton <paul.burton@imgtec.com> Cc: linux-mips@linux-mips.org Cc: linux-kernel@vger.kernel.org Patchwork: https://patchwork.linux-mips.org/patch/11184/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Diffstat (limited to 'arch/mips/Kconfig')
-rw-r--r--arch/mips/Kconfig17
1 files changed, 14 insertions, 3 deletions
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index c08e7016c77a..1943377ea491 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -2530,6 +2530,9 @@ choice
help
Allows the configuration of the timer frequency.
+ config HZ_24
+ bool "24 HZ" if SYS_SUPPORTS_24HZ || SYS_SUPPORTS_ARBIT_HZ
+
config HZ_48
bool "48 HZ" if SYS_SUPPORTS_48HZ || SYS_SUPPORTS_ARBIT_HZ
@@ -2553,6 +2556,9 @@ choice
endchoice
+config SYS_SUPPORTS_24HZ
+ bool
+
config SYS_SUPPORTS_48HZ
bool
@@ -2576,13 +2582,18 @@ config SYS_SUPPORTS_1024HZ
config SYS_SUPPORTS_ARBIT_HZ
bool
- default y if !SYS_SUPPORTS_48HZ && !SYS_SUPPORTS_100HZ && \
- !SYS_SUPPORTS_128HZ && !SYS_SUPPORTS_250HZ && \
- !SYS_SUPPORTS_256HZ && !SYS_SUPPORTS_1000HZ && \
+ default y if !SYS_SUPPORTS_24HZ && \
+ !SYS_SUPPORTS_48HZ && \
+ !SYS_SUPPORTS_100HZ && \
+ !SYS_SUPPORTS_128HZ && \
+ !SYS_SUPPORTS_250HZ && \
+ !SYS_SUPPORTS_256HZ && \
+ !SYS_SUPPORTS_1000HZ && \
!SYS_SUPPORTS_1024HZ
config HZ
int
+ default 24 if HZ_24
default 48 if HZ_48
default 100 if HZ_100
default 128 if HZ_128