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This commit corrects problems with the previous wake implementation by implementing suspend and resume power management operations and the driver shutdown operation. Wake masks are used to keep track of which GPIO should wake the device. On suspend the GPIO state is saved and the possible wakeup sources are explicitly unmasked in the hardware. Non-wakeup sources are explicitly masked so IRQCHIP_MASK_ON_SUSPEND is no longer necessary. The saved state of the GPIO is restored upon resume. It is important not to write to the GPIO status register since this has the effect of clearing bits. The status register is explicitly removed from the register save and restore to ensure this. The shutdown operation allows the hardware to be put into the same quiesced state as the suspend operation and removes the need for the reboot notifier. Unfortunately, there appears to be some confusion about whether a pending disabled wake interrupt should wake the system. If a wake capable interrupt is disabled using the default "lazy disable" behavior and it is triggered before the suspend_device_irq call the interrupt hardware will be acknowledged by mask_ack_irq and the IRQS_PENDING flag is added to its state. However, the IRQS_PENDING flag of wake interrupts is not checked to prevent the transition to suspend and the hardware has been acked which prevents its wakeup. If the lazy disabled interrupt is triggered after the call to suspend_device_irqs then the wakeup logic will abort the suspend. The irq_disable method is defined by this GPIO driver to prevent lazy disable so that the pending hardware state remains asserted allowing the hardware to wake and providing a consistent behavior. In addition, the IRQ_DISABLE_UNLAZY flag is set for the non-wake parent interrupt as a convenience to prevent the need to add code to the brcmstb_gpio_irq_handler to support "lazy disable" of the non-wake parent interrupt when it is disabled during suspend and resume. Chained interrupt parents are not normally disabled, but these GPIO devices have different parent interrupts for wake and non-wake handling. It is convenient to mask the non-wake parent when suspending to preserve the hardware state for proper wakeup accounting when the driver is resumed. Signed-off-by: Doug Berger <opendmb@gmail.com> Acked-by: Gregory Fong <gregory.0xf0@gmail.com> Reviewed-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: Linus Walleij <linus.walleij@linaro.org> |
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Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.