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sh: Ensure ST40-300 BogoMIPS value is consistent

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A strange variation was seen in the BogoMIPS figure for the ST40-300.
This was eventually tracked down to sensitivity to the alignment of
the loop. So add an align directive to ensure this doesn't occur.

Signed-off-by: Stuart Menefy <stuart.menefy@st.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
This commit is contained in:
Stuart Menefy 2010-11-11 18:26:31 +00:00 committed by Paul Mundt
parent 795abaf1e4
commit a086536858
1 changed files with 10 additions and 0 deletions
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10
arch/sh/lib/delay.c
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@ -10,6 +10,16 @@
void __delay(unsigned long loops)
{
__asm__ __volatile__(
/*
* ST40-300 appears to have an issue with this code,
* normally taking two cycles each loop, as with all
* other SH variants. If however the branch and the
* delay slot straddle an 8 byte boundary, this increases
* to 3 cycles.
* This align directive ensures this doesn't occur.
*/
".balign 8\n\t"
"tst %0, %0\n\t"
"1:\t"
"bf/s 1b\n\t"