77da2d910a
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@ti.com> Reviewed-by: Paul Walmsley <paul@pwsan.com> Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com> |
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