NAK; see details below On Thursday 27 August 2009, Anton Vorontsov wrote: > RTC core won't allow wakeup alarms to be set if RTC devices' parent > (i.e. i2c_client or spi_device) isn't wakeup capable. Quite rightly so ... being wakeup-capable is config-specific. > For I2C devices there is I2C_CLIENT_WAKE flag exists that we can pass > via board info, and if set, I2C core will initialize wakeup capability. > For SPI devices there is no such flag at all. So why not add it for SPI? If it's an issue, it's not unique to RTC devices. > I believe that it's not platform code responsibility to allow or > disallow wakeups, instead, drivers themselves should set the capability > if a device can trigger wakeups. Drivers can't generally know if that's possible though. They need to be told that it is, by platform code. Most devices can't issue wakeup events. > That's what drivers/base/power/sysfs.c says: > > * It is the responsibility of device drivers to enable (or disable) > * wakeup signaling as part of changing device power states, respecting > * the policy choices provided through the driver model. > > I2C and SPI RTC devices send wakeup events via interrupt lines, so we > should set the wakeup capability if IRQ is routed. Re-read the quoted sentence. You're saying that policy choices should be hard-wired into the driver; contrary to that quote. (In this case the choice is one that platform code must report, and which the hardware designer made: if the device can issue wakeup events.) > Ideally we should also check irq for wakeup capability before setting > device's capability, i.e. > > if (can_irq_wake(irq)) > device_set_wakeup_capable(&client->dev, 1); > > But there is no can_irq_wake() call exist, and it is not that trivial > to implement it for all interrupts controllers and complex/cascaded > setups. That is why platform code should device_init_wakeup() and drivers should check device_can_wakeup(dev) ... > drivers/base/power/sysfs.c also covers these cases: > > * Devices may not be able to generate wakeup events from all power > * states. Also, the events may be ignored in some configurations; > * for example, they might need help from other devices that aren't > * active > > So there is no guarantee that wakeup will actually work, Yes there is ... it's only **exceptional** cases where it can't work. Your patch would make it routine that those flags be unreliable; pretty nasty. _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
