[PATCH v2] Alchemy: override loops_per_jiffy detection

[PATCH v2] Alchemy: override loops_per_jiffy detection

[Manuel Lauss]

loops_per_jiffy depends on coreclk speed;  preset it instead of
letting the kernel waste precious microseconds trying to approximate it.

Signed-off-by: Manuel Lauss <manuel.lauss@gmail.com>
---
V2: no need to exclude MACH_ALCHEMY from GENERIC_CALIBRATE_DELAY
    setting preset_lpj early is enough.

As always, run-tested on DB1200 and another Au1200 system.

 arch/mips/alchemy/common/setup.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/arch/mips/alchemy/common/setup.c b/arch/mips/alchemy/common/setup.c
index 3f036b3..6184baa 100644
--- a/arch/mips/alchemy/common/setup.c
+++ b/arch/mips/alchemy/common/setup.c
@@ -27,6 +27,7 @@
 
 #include <linux/init.h>
 #include <linux/ioport.h>
+#include <linux/jiffies.h>
 #include <linux/module.h>
 #include <linux/pm.h>
 
@@ -53,6 +54,9 @@ void __init plat_mem_setup(void)
 	printk(KERN_INFO "(PRId %08x) @ %lu.%02lu MHz\n", read_c0_prid(),
 	       est_freq / 1000000, ((est_freq % 1000000) * 100) / 1000000);
 
+	/* this is faster than wasting cycles trying to approximate it */
+	preset_lpj = (est_freq >> 1) / HZ;
+
 	_machine_restart = au1000_restart;
 	_machine_halt = au1000_halt;
 	pm_power_off = au1000_power_off;
-- 
1.6.4

Re: [PATCH v2] Alchemy: override loops_per_jiffy detection

[Ralf Baechle]

On Thu, Aug 27, 2009 at 07:21:18PM +0200, Manuel Lauss wrote:

> loops_per_jiffy depends on coreclk speed;  preset it instead of
> letting the kernel waste precious microseconds trying to approximate it.
> 
> Signed-off-by: Manuel Lauss <manuel.lauss@gmail.com>

Thanks, applied.

  Ralf