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Re: [Qemu-devel] [PATCH] m68k: change default system clock for m5208evb


From: Greg Ungerer
Subject: Re: [Qemu-devel] [PATCH] m68k: change default system clock for m5208evb
Date: Tue, 27 Sep 2016 23:22:38 +1000
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.3.0

Hi Laurent,

On 27/09/16 18:11, Laurent Vivier wrote:
Le 27/09/2016 à 09:33, Thomas Huth a écrit :
On 27.09.2016 03:29, Greg Ungerer wrote:
The shipping default setting for the Freescale M5208EVB board is to run
the CPU at 166MHz. The current qemu emulation code for this board is
defaulting to 66MHz. This results in time appearing to run way to slowly.
So a "sleep 5" in a standard ColdFire Linux build takes almost 15
seconds in real time to actually complete.

Change the hard coded default to match the default hardware setting.

Signed-off-by: Greg Ungerer <address@hidden>
---
 hw/m68k/mcf5208.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hw/m68k/mcf5208.c b/hw/m68k/mcf5208.c
index 9240ebf..2d0b464 100644
--- a/hw/m68k/mcf5208.c
+++ b/hw/m68k/mcf5208.c
@@ -21,7 +21,7 @@
 #include "elf.h"
 #include "exec/address-spaces.h"

-#define SYS_FREQ 66000000
+#define SYS_FREQ 166000000

Good catch. But actually, the M5208EVB User's Manual talks about 166.67
MHz, so while you're at it, maybe you should change it to 166666666 instead?

In this case, it should be better to use a period of 6000000 ns (and
ptimer_set_period() instead of ptimer_set_freq()).

Why is that better in this case?
All the documentation lists it as 166.67MHz, even on the PCB.
Isn't it clearer to define it based on the actual value documented?

Regards
Greg




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