[U-Boot-Users] [PATCH 4/4] add csb637 (at91rm9200) support
Hi,
this patch switches the at91rm9200 to synchronous clock mode after initialization (it would otherwise stay in FastBus mode which is the _slowest_ clock mode). This lets the core run at full speed when not doing bus accesses, increasing overall performance by a factor of four.
Changelog: * patch by Anders Larsen, 2004-04-29 set the at91rm9200 clock to synchronous mode
Cheers Anders
Steven Scholz steven.scholz@imc-berlin.de schreibt:
this patch switches the at91rm9200 to synchronous clock mode after initialization (it would otherwise stay in FastBus mode which is the _slowest_ clock mode).
But I thought FastBus mode is the prefered setting for ARM cpus.
Hi Steven,
FastBus is the default after reset but is not intended for normal operation.
Quote from the ARM920T Technical Reference Manual (ARM DDI 0151C): "On reset, the ARM920T is put into FastBus mode and operates using BCLK. A typical use for FastBus mode is to execute startup code while configuring a PLL under software control to produce FCLK at a higher frequency. When the PLL has stabilized and locked, you can switch the ARM920T to synchronous or asynchronous clocking using FCLK for normal operation."
Cheers Anders
In message fc.004c4e480031ce90004c4e480031ce90.31cec2@rea.de you wrote:
Changelog:
- patch by Anders Larsen, 2004-04-29 set the at91rm9200 clock to synchronous mode
Added, thanks.
Best regards,
Wolfgang Denk
participants (3)
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Anders Larsen -
Steven Scholz -
Wolfgang Denk