[PATCH 1/3] pm: at91: pm_slowclock: fix suspend/resume hang up in timeouts

From: Wenyou Yang
Date: Thu Feb 05 2015 - 01:02:53 EST


From: Sylvain Rochet <sylvain.rochet@xxxxxxxxxxxx>

Removed timeout on XTAL, PLL lock and Master Clock Ready, hang if
something went wrong instead of continuing in unknown condition. There
is not much we can do if a PLL lock never ends, we are running in SRAM
and we will not be able to connect back the sdram or ddram in order to
be able to fire up a message or just panic.

As a bonus, not decounting the timeout register in slow clock mode
reduce cumulated suspend time and resume time from ~17ms to ~15ms.

Signed-off-by: Sylvain Rochet <sylvain.rochet@xxxxxxxxxxxx>
Acked-by: Wenyou.Yang <wenyou.yang@xxxxxxxxx>
---
arch/arm/mach-at91/pm_slowclock.S | 33 ++++-----------------------------
1 file changed, 4 insertions(+), 29 deletions(-)

diff --git a/arch/arm/mach-at91/pm_slowclock.S b/arch/arm/mach-at91/pm_slowclock.S
index 2001877..79dfdbe 100644
--- a/arch/arm/mach-at91/pm_slowclock.S
+++ b/arch/arm/mach-at91/pm_slowclock.S
@@ -34,11 +34,6 @@
*/
#undef SLOWDOWN_MASTER_CLOCK

-#define MCKRDY_TIMEOUT 1000
-#define MOSCRDY_TIMEOUT 1000
-#define PLLALOCK_TIMEOUT 1000
-#define PLLBLOCK_TIMEOUT 1000
-
pmc .req r0
sdramc .req r1
ramc1 .req r2
@@ -50,56 +45,36 @@ tmp2 .req r5
* Wait until master clock is ready (after switching master clock source)
*/
.macro wait_mckrdy
- mov tmp2, #MCKRDY_TIMEOUT
-1: sub tmp2, tmp2, #1
- cmp tmp2, #0
- beq 2f
- ldr tmp1, [pmc, #AT91_PMC_SR]
+1: ldr tmp1, [pmc, #AT91_PMC_SR]
tst tmp1, #AT91_PMC_MCKRDY
beq 1b
-2:
.endm

/*
* Wait until master oscillator has stabilized.
*/
.macro wait_moscrdy
- mov tmp2, #MOSCRDY_TIMEOUT
-1: sub tmp2, tmp2, #1
- cmp tmp2, #0
- beq 2f
- ldr tmp1, [pmc, #AT91_PMC_SR]
+1: ldr tmp1, [pmc, #AT91_PMC_SR]
tst tmp1, #AT91_PMC_MOSCS
beq 1b
-2:
.endm

/*
* Wait until PLLA has locked.
*/
.macro wait_pllalock
- mov tmp2, #PLLALOCK_TIMEOUT
-1: sub tmp2, tmp2, #1
- cmp tmp2, #0
- beq 2f
- ldr tmp1, [pmc, #AT91_PMC_SR]
+1: ldr tmp1, [pmc, #AT91_PMC_SR]
tst tmp1, #AT91_PMC_LOCKA
beq 1b
-2:
.endm

/*
* Wait until PLLB has locked.
*/
.macro wait_pllblock
- mov tmp2, #PLLBLOCK_TIMEOUT
-1: sub tmp2, tmp2, #1
- cmp tmp2, #0
- beq 2f
- ldr tmp1, [pmc, #AT91_PMC_SR]
+1: ldr tmp1, [pmc, #AT91_PMC_SR]
tst tmp1, #AT91_PMC_LOCKB
beq 1b
-2:
.endm

.text
--
1.7.9.5

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