Thread (38 messages) 38 messages, 5 authors, 2012-07-24
STALE5063d

[PATCH v2 2/2] ARM: delay: allow timer-based delay implementation to be selected

From: Will Deacon <hidden>
Date: 2012-07-02 21:53:22

On Mon, Jul 02, 2012 at 08:14:57PM +0100, Stephen Boyd wrote:
On 06/29/12 10:33, Will Deacon wrote:
quoted
This patch allows a timer-based delay implementation to be selected by
switching the delay routines over to use get_cycles, which is
implemented in terms of read_current_timer. This further allows us to
skip the loop calibration and have a consistent delay function in the
face of core frequency scaling.

To avoid the pain of dealing with memory-mapped counters, this
implementation uses the co-processor interface to the architected timers
when they are available. The previous loop-based implementation is
kept around for CPUs without the architected timers and we retain both
the maximum delay (2ms) and the corresponding conversion factors for
determining the number of loops required for a given interval. Since the
indirection of the timer routines will only work when called from C,
the sa1100 sleep routines are modified to branch to the loop-based delay
functions directly.

Signed-off-by: Will Deacon <redacted>
Reviewed-by: Stephen Boyd <redacted>
Thanks for the reviews Stephen. I'll stick this in the patch system this
week.

Cheers,

Will
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