> > [...] > > > >> + /* > >> + * CORE_SW_RST above may trigger power irq if previous status of > >> PWRCTL > >> + * was either BUS_ON or IO_HIGH_V. So before we enable the power > >> irq > >> + * interrupt in GIC (by registering the interrupt handler), we > >> need to > >> + * ensure that any pending power irq interrupt status is > >> acknowledged > >> + * otherwise power irq interrupt handler would be fired > >> prematurely. > >> + */ > >> + irq_status = readl_relaxed(msm_host->core_mem + > >> CORE_PWRCTL_STATUS); > >> + writel_relaxed(irq_status, (msm_host->core_mem + > >> CORE_PWRCTL_CLEAR)); > >> + irq_ctl = readl_relaxed(msm_host->core_mem + CORE_PWRCTL_CTL); > >> + if (irq_status & (CORE_PWRCTL_BUS_ON | CORE_PWRCTL_BUS_OFF)) > >> + irq_ctl |= CORE_PWRCTL_BUS_SUCCESS; > >> + if (irq_status & (CORE_PWRCTL_IO_HIGH | CORE_PWRCTL_IO_LOW)) > >> + irq_ctl |= CORE_PWRCTL_IO_SUCCESS; > >> + writel_relaxed(irq_ctl, (msm_host->core_mem + CORE_PWRCTL_CTL)); > >> + /* > >> + * Ensure that above writes are propogated before interrupt > >> enablement > >> + * in GIC. > >> + */ > >> + mb(); > > > > Does this guarantee that the device has finished responding to the write > > and deasserted the interrupt line (i.e. does the device only acknowledge > > the write once that is true)? > > > > I am not sure that i understand your concern. The write to > CORE_PWRCTL_CTL should acknowledge and deassert the interrupt.
The mb() ensures that the write has reached the device, and the device's slave interface has acknowledged the write. On some devices this acknowledgement of the write can be asynchronous with respect to the device changing state in response to the write (i.e. the interrupt might get deasserted a short time after the write completes). Typically there is a register that should be polled to see whether the state change has completed. Does the acknowledgement of the write only occur once the device has changed state? Or might it change state in the background? Thanks, Mark -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
