On Monday, December 13, 2010, ykzhao wrote: > On Sun, 2010-12-12 at 06:39 +0800, Rafael J. Wysocki wrote: > > Hi Len, > > > > The following three patches seem to have been dropped from your 'test' branch. > > > > If that happened by accident, please reapply. Otherwise, please let me know > > what's wrong with the patches so that I can fix them. > > > > [1/3] - Make fujitsu_laptop use acpi_bus_update_power() instead of > > acpi_bus_get_power() which is unsafe. > > ïIt seems that the function of acpi_bus_update_power not only obtains > the current power state, but also set the corresponding power state. > Right? Yes, it does. > If the device reports the bogus power state, maybe we will set the > incorrect power state for the corresponding device when using the > function of acpi_bus_update_power instead of acpi_bus_get_power. Please actually look at acpi_bus_get_power() (being removed by [2/3]) and note that it _also_ modifies device->power.state (it doesn't return the state, actually), so if the returned state is really bogus, we'll have a mismatch between device->power.state and the real state of the device. This cannot be good. In the case of acpi_bus_update_power() we at least _try_ to keep the two things in sync. Note, this is _essentially_ important for power resources (if acpi_bus_get_power() is used, the refcounts are _guaranteed_ not to be in sync with device->power.state in some situations). > In such case maybe the device can't work well. > > The bogus power state is reported for some devices on some laptops. For > example: > http://bugzilla.kernel.org/show_bug.cgi?id=8049 > http://bugzilla.kernel.org/show_bug.cgi?id=11000 These bugs are about acpi_bus_set_power() doing the acpi_bus_get_power() before setting the state, which is wrong and is being removed by my previous patches (now in the Len's tree). Thanks, Rafael -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
