On Saturday 23 May 2009, Kim Kyuwon wrote: > On Sat, May 23, 2009 at 6:25 AM, Rafael J. Wysocki <rjw@xxxxxxx> wrote: > > On Friday 22 May 2009, Kim Kyuwon wrote: > >> On Fri, May 22, 2009 at 11:53 AM, Kim Kyuwon <chammoru@xxxxxxxxx> wrote: > >> > On Wed, May 6, 2009 at 8:27 AM, Rafael J. Wysocki <rjw@xxxxxxx> wrote: > >> >> On Wednesday 06 May 2009, Kevin Hilman wrote: > >> >>> Arve Hjønnevåg <arve@xxxxxxxxxxx> writes: > >> >>> > >> >>> > On Tue, May 5, 2009 at 8:52 AM, Kevin Hilman > >> >>> > <khilman@xxxxxxxxxxxxxxxxxxx> wrote: > >> >>> >> Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> writes: > >> >>> >> > >> >>> >>> On Mon, 4 May 2009 17:27:04 -0700 Kevin Hilman <khilman@xxxxxxxxxxxxxxxxxxx> wrote: > >> >>> >>> > >> >>> >>>> Interrupts that are flagged as wakeup sources via set_irq_wake() > >> >>> >>>> should not be disabled for suspend. > >> >>> >>>> > >> >>> >>> > >> >>> >>> Why not? > >> >>> >>> > >> >>> >> > >> >>> >> If an interrupt is a wakeup source, and it is disabled at the chip > >> >>> >> level, it will no longer generate interrupts, and thus no longer wake > >> >>> >> up the system. > >> >>> >> > >> >>> >> I'd be interested in hearing why wakeup interrupts should be disabled > >> >>> >> during suspend. > >> >> > >> >> That depends on whether or not they are used for anything else than wake-up. > >> >> > >> >>> > >> >>> [...] > >> >>> > >> >>> >>> > >> >>> >>> If this fixes some bug then please provide a description of that bug? > >> >>> >> > >> >>> >> The bug is that on TI OMAP, interrupts that are used for wakeup events > >> >>> >> are disabled by this code causing the system to no longer wake up. > >> >>> > > >> >>> > What do you do if the interrupt triggers right after your driver has > >> >>> > returned from its late suspend hook? > >> >>> > >> >>> If it's a wakeup IRQ, I assume you want it to prevent suspend. > >> >>> > >> >>> But I don't see how that can happen in the current code. IIUC, by the > >> >>> time your late suspend hook is run, your device IRQ is already > >> >>> disabled, so it won't trigger an interrupt that will be caught by > >> >>> check_wakeup_irqs() anyways. > >> >> > >> >> My understanding of __disable_irq() was that it didn't actually disable the > >> >> IRQ at the hardware level, allowing the CPU to actually receive the interrupt > >> >> and acknowledge it, but preventing the device driver for receiving it. Does > >> >> it work differently on the affected systems? > >> > > >> > Hi, Rafael. > >> > Sorry for bring the old issue but please let me ask you about > >> > suspend_device_irqs() function. > >> > > >> > __disable_irq() disables the IRQ at the hardware level in the > >> > following irq_chips > >> > > >> > i8259A_chip > >> > i8259_pic > >> > i8259A_chip > >> > bfin_internal_irqchip > >> > crisv10_irq_type > >> > crisv32_irq_type > >> > h8300irq_chip > >> > m_irq_chip > >> > mn10300_cpu_pic_level > >> > xtensa_irq_chip > >> > iop13xx_msi_chip > >> > msi_irq > >> > > >> > Because these irq_chips mask interrupts in 'disable' hook. > >> > > >> > Thus, your suspend_device_irqs() function disables all IRQs at the > >> > hardware level on all architectures which use irq_chips listed above > >> > in suspend state. > >> > Is this really what you wanted? > >> > > >> > If interrupt can wake up the system from suspend in some architectures > >> > and if disable_irq_wake is not supported in these architectures, I > >> > wonder if suspend_device_irqs() don't allow waking up by interrupt. > >> > > >> > Regards, > >> > Kyuwon > >> > > >> > >> I saw resume_device_irqs() is invoked after arch_suspend_enable_irqs() > >> in your resume code. > >> So in this gap between resume_device_irqs() and > >> arch_suspend_enable_irqs(), a few interrupts would be discarded. > >> i.e, a few data would be lost. > >> > >> If keypad wake up the system, first key pressed information would be lost. > >> If I2C, USB, SPI, UART wake up the system, first a few data would be lost. > >> > >> Did you also consider this issue? > > > > I think it would happen anyway with the old code, wouldn't it? > > That's not quite right. > > For example, let's assume a keypad device is alive in suspend/resume > state to wake up the system. Before arch_suspend_enable_irqs(), none > of keypad irqs is dropped. It is just pending. > > But in your code, a few irqs are discarded due to your resume_device_irqs(). You can't say for sure they are discarded, but there's a small window in which they can be discarded. The question is whether it does cause problems in practice. Anyway, IMO the device that caused a wake-up event should be deactivated before arch_suspend_enable_irqs() and remain inactive until its driver is actually ready to handle interrupts generated by it. Thanks, Rafael _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
