From: Jon Hunter <jon-hunter@xxxxxx>
There are two scenarios where a race condition could result in a hang in the
prcm_interrupt handler. These are:
1). Waiting for PRM_IRQSTATUS_MPU register to clear.
Bit 0 of the PRM_IRQSTATUS_MPU register indicates that a wake-up event is
pending for the MPU. This bit can only be cleared if the all the wake-up events
latched in the various PM_WKST_x registers have been cleared. If a wake-up event
occurred during the processing of the prcm interrupt handler, after the
corresponding PM_WKST_x register was checked but before the PRM_IRQSTATUS_MPU
was cleared, then the CPU would be stuck forever waiting for bit 0 in
PRM_IRQSTATUS_MPU to be cleared.
2). Waiting for the PM_WKST_x register to clear.
Some power domains have more than one wake-up source. The PM_WKST_x registers
indicate the source of a wake-up event and need to be cleared after a wake-up
event occurs. When the PM_WKST_x registers are read and before they are cleared,
it is possible that another wake-up event could occur causing another bit to be
set in one of the PM_WKST_x registers. If this did occur after reading a
PM_WKST_x register then the CPU would miss this event and get stuck forever in
a loop waiting for that PM_WKST_x register to clear.
This patch address the above race conditions that would result in a hang.
Signed-off-by: Jon Hunter <jon-hunter@xxxxxx>
---
arch/arm/mach-omap2/pm34xx.c | 169 +++++++++++++++++++++++-------------------
1 files changed, 94 insertions(+), 75 deletions(-)
diff --git a/arch/arm/mach-omap2/pm34xx.c b/arch/arm/mach-omap2/pm34xx.c
index 7a4a525..0545262 100644
--- a/arch/arm/mach-omap2/pm34xx.c
+++ b/arch/arm/mach-omap2/pm34xx.c
@@ -200,91 +200,110 @@ static irqreturn_t prcm_interrupt_handler (int irq, void *dev_id)
u32 wkst, irqstatus_mpu;
u32 fclk, iclk;
- /* WKUP */
- wkst = prm_read_mod_reg(WKUP_MOD, PM_WKST);
- if (wkst) {
- iclk = cm_read_mod_reg(WKUP_MOD, CM_ICLKEN);
- fclk = cm_read_mod_reg(WKUP_MOD, CM_FCLKEN);
- cm_set_mod_reg_bits(wkst, WKUP_MOD, CM_ICLKEN);
- cm_set_mod_reg_bits(wkst, WKUP_MOD, CM_FCLKEN);
- prm_write_mod_reg(wkst, WKUP_MOD, PM_WKST);
- while (prm_read_mod_reg(WKUP_MOD, PM_WKST))
- cpu_relax();
- cm_write_mod_reg(iclk, WKUP_MOD, CM_ICLKEN);
- cm_write_mod_reg(fclk, WKUP_MOD, CM_FCLKEN);
- }
-
- /* CORE */
- wkst = prm_read_mod_reg(CORE_MOD, PM_WKST1);
- if (wkst) {
- iclk = cm_read_mod_reg(CORE_MOD, CM_ICLKEN1);
- fclk = cm_read_mod_reg(CORE_MOD, CM_FCLKEN1);
- cm_set_mod_reg_bits(wkst, CORE_MOD, CM_ICLKEN1);
- cm_set_mod_reg_bits(wkst, CORE_MOD, CM_FCLKEN1);
- prm_write_mod_reg(wkst, CORE_MOD, PM_WKST1);
- while (prm_read_mod_reg(CORE_MOD, PM_WKST1))
- cpu_relax();
- cm_write_mod_reg(iclk, CORE_MOD, CM_ICLKEN1);
- cm_write_mod_reg(fclk, CORE_MOD, CM_FCLKEN1);
- }
- wkst = prm_read_mod_reg(CORE_MOD, OMAP3430ES2_PM_WKST3);
- if (wkst) {
- iclk = cm_read_mod_reg(CORE_MOD, CM_ICLKEN3);
- fclk = cm_read_mod_reg(CORE_MOD, OMAP3430ES2_CM_FCLKEN3);
- cm_set_mod_reg_bits(wkst, CORE_MOD, CM_ICLKEN3);
- cm_set_mod_reg_bits(wkst, CORE_MOD, OMAP3430ES2_CM_FCLKEN3);
- prm_write_mod_reg(wkst, CORE_MOD, OMAP3430ES2_PM_WKST3);
- while (prm_read_mod_reg(CORE_MOD, OMAP3430ES2_PM_WKST3))
- cpu_relax();
- cm_write_mod_reg(iclk, CORE_MOD, CM_ICLKEN3);
- cm_write_mod_reg(fclk, CORE_MOD, OMAP3430ES2_CM_FCLKEN3);
- }
+ do {
+ /* WKUP */
+ wkst = prm_read_mod_reg(WKUP_MOD, PM_WKST);
+ if (wkst) {
+ iclk = cm_read_mod_reg(WKUP_MOD, CM_ICLKEN);
+ fclk = cm_read_mod_reg(WKUP_MOD, CM_FCLKEN);
+ while (wkst) {
+ cm_set_mod_reg_bits(wkst, WKUP_MOD, CM_ICLKEN);
+ cm_set_mod_reg_bits(wkst, WKUP_MOD, CM_FCLKEN);
+ prm_write_mod_reg(wkst, WKUP_MOD, PM_WKST);
+ wkst = prm_read_mod_reg(WKUP_MOD, PM_WKST);
+ }
+ cm_write_mod_reg(iclk, WKUP_MOD, CM_ICLKEN);
+ cm_write_mod_reg(fclk, WKUP_MOD, CM_FCLKEN);
+ }
- /* PER */
- wkst = prm_read_mod_reg(OMAP3430_PER_MOD, PM_WKST);
- if (wkst) {
- iclk = cm_read_mod_reg(OMAP3430_PER_MOD, CM_ICLKEN);
- fclk = cm_read_mod_reg(OMAP3430_PER_MOD, CM_FCLKEN);
- cm_set_mod_reg_bits(wkst, OMAP3430_PER_MOD, CM_ICLKEN);
- cm_set_mod_reg_bits(wkst, OMAP3430_PER_MOD, CM_FCLKEN);
- prm_write_mod_reg(wkst, OMAP3430_PER_MOD, PM_WKST);
- while (prm_read_mod_reg(OMAP3430_PER_MOD, PM_WKST))
- cpu_relax();
- cm_write_mod_reg(iclk, OMAP3430_PER_MOD, CM_ICLKEN);
- cm_write_mod_reg(fclk, OMAP3430_PER_MOD, CM_FCLKEN);
- }
+ /* CORE */
+ wkst = prm_read_mod_reg(CORE_MOD, PM_WKST1);
+ if (wkst) {
+ iclk = cm_read_mod_reg(CORE_MOD, CM_ICLKEN1);
+ fclk = cm_read_mod_reg(CORE_MOD, CM_FCLKEN1);
+ while (wkst) {
+ cm_set_mod_reg_bits(wkst, CORE_MOD, CM_ICLKEN1);
+ cm_set_mod_reg_bits(wkst, CORE_MOD, CM_FCLKEN1);
+ prm_write_mod_reg(wkst, CORE_MOD, PM_WKST1);
+ wkst = prm_read_mod_reg(CORE_MOD, PM_WKST1);
+ }
+ cm_write_mod_reg(iclk, CORE_MOD, CM_ICLKEN1);
+ cm_write_mod_reg(fclk, CORE_MOD, CM_FCLKEN1);
+ }
+ wkst = prm_read_mod_reg(CORE_MOD, OMAP3430ES2_PM_WKST3);
+ if (wkst) {
+ iclk = cm_read_mod_reg(CORE_MOD, CM_ICLKEN3);
+ fclk = cm_read_mod_reg(CORE_MOD,
+ OMAP3430ES2_CM_FCLKEN3);
+ while (wkst) {
+ cm_set_mod_reg_bits(wkst, CORE_MOD, CM_ICLKEN3);
+ cm_set_mod_reg_bits(wkst, CORE_MOD,
+ OMAP3430ES2_CM_FCLKEN3);
+ prm_write_mod_reg(wkst, CORE_MOD,
+ OMAP3430ES2_PM_WKST3);
+ wkst = prm_read_mod_reg(CORE_MOD,
+ OMAP3430ES2_PM_WKST3);
+ }
+ cm_write_mod_reg(iclk, CORE_MOD, CM_ICLKEN3);
+ cm_write_mod_reg(fclk, CORE_MOD,
+ OMAP3430ES2_CM_FCLKEN3);
+ }
- if (omap_rev() > OMAP3430_REV_ES1_0) {
- /* USBHOST */
- wkst = prm_read_mod_reg(OMAP3430ES2_USBHOST_MOD, PM_WKST);
+ /* PER */
+ wkst = prm_read_mod_reg(OMAP3430_PER_MOD, PM_WKST);
if (wkst) {
- iclk = cm_read_mod_reg(OMAP3430ES2_USBHOST_MOD,
+ iclk = cm_read_mod_reg(OMAP3430_PER_MOD, CM_ICLKEN);
+ fclk = cm_read_mod_reg(OMAP3430_PER_MOD, CM_FCLKEN);
+ while (wkst) {
+ cm_set_mod_reg_bits(wkst, OMAP3430_PER_MOD,
+ CM_ICLKEN);
+ cm_set_mod_reg_bits(wkst, OMAP3430_PER_MOD,
+ CM_FCLKEN);
+ prm_write_mod_reg(wkst, OMAP3430_PER_MOD,
+ PM_WKST);
+ wkst = prm_read_mod_reg(OMAP3430_PER_MOD,
+ PM_WKST);
+ }
+ cm_write_mod_reg(iclk, OMAP3430_PER_MOD, CM_ICLKEN);
+ cm_write_mod_reg(fclk, OMAP3430_PER_MOD, CM_FCLKEN);
+ }
+
+ if (omap_rev() > OMAP3430_REV_ES1_0) {
+ /* USBHOST */
+ wkst = prm_read_mod_reg(OMAP3430ES2_USBHOST_MOD,
+ PM_WKST);
+ if (wkst) {
+ iclk = cm_read_mod_reg(OMAP3430ES2_USBHOST_MOD,
CM_ICLKEN);
- fclk = cm_read_mod_reg(OMAP3430ES2_USBHOST_MOD,
+ fclk = cm_read_mod_reg(OMAP3430ES2_USBHOST_MOD,
CM_FCLKEN);
- cm_set_mod_reg_bits(wkst, OMAP3430ES2_USBHOST_MOD,
- CM_ICLKEN);
- cm_set_mod_reg_bits(wkst, OMAP3430ES2_USBHOST_MOD,
- CM_FCLKEN);
- prm_write_mod_reg(wkst, OMAP3430ES2_USBHOST_MOD,
- PM_WKST);
- while (prm_read_mod_reg(OMAP3430ES2_USBHOST_MOD,
- PM_WKST))
- cpu_relax();
- cm_write_mod_reg(iclk, OMAP3430ES2_USBHOST_MOD,
+ while (wkst) {
+ cm_set_mod_reg_bits(wkst,
+ OMAP3430ES2_USBHOST_MOD,
+ CM_ICLKEN);
+ cm_set_mod_reg_bits(wkst,
+ OMAP3430ES2_USBHOST_MOD,
+ CM_FCLKEN);
+ prm_write_mod_reg(wkst,
+ OMAP3430ES2_USBHOST_MOD,
+ PM_WKST);
+ wkst = prm_read_mod_reg(
+ OMAP3430ES2_USBHOST_MOD,
+ PM_WKST);
+ }
+ cm_write_mod_reg(iclk, OMAP3430ES2_USBHOST_MOD,
CM_ICLKEN);
- cm_write_mod_reg(fclk, OMAP3430ES2_USBHOST_MOD,
+ cm_write_mod_reg(fclk, OMAP3430ES2_USBHOST_MOD,
CM_FCLKEN);
+ }
}
- }
- irqstatus_mpu = prm_read_mod_reg(OCP_MOD,
- OMAP3_PRM_IRQSTATUS_MPU_OFFSET);
- prm_write_mod_reg(irqstatus_mpu, OCP_MOD,
- OMAP3_PRM_IRQSTATUS_MPU_OFFSET);
+ irqstatus_mpu = prm_read_mod_reg(OCP_MOD,
+ OMAP3_PRM_IRQSTATUS_MPU_OFFSET);
+ prm_write_mod_reg(irqstatus_mpu, OCP_MOD,
+ OMAP3_PRM_IRQSTATUS_MPU_OFFSET);
- while (prm_read_mod_reg(OCP_MOD, OMAP3_PRM_IRQSTATUS_MPU_OFFSET))
- cpu_relax();
+ } while (prm_read_mod_reg(OCP_MOD, OMAP3_PRM_IRQSTATUS_MPU_OFFSET));
return IRQ_HANDLED;
}
--
1.6.0.4
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