On Mon, Oct 30, 2017 at 2:14 PM, Hans de Goede <hdegoede@xxxxxxxxxx> wrote: > Hi, > > > On 16-10-17 13:44, Hans de Goede wrote: >> >> Hi, >> >> On 16-10-17 01:47, Rafael J. Wysocki wrote: >>> >>> On Sun, Oct 15, 2017 at 9:24 PM, Hans de Goede <hdegoede@xxxxxxxxxx> >>> wrote: >>>> >>>> Most Bay and Cherry Trail devices use a generic DSDT with all possible >>>> peripheral devices present in the DSDT, with their _STA returning 0x00 >>>> or >>>> 0x0f based on AML variables which describe what is actually present on >>>> the board. >>>> >>>> Since ACPI device objects with a 0x00 status (not present) still get an >>>> entry under /sys/bus/acpi/devices, and those entry had an acpi:PNPID >>>> modalias, userspace would end up loading modules for non present >>>> hardware. >>>> >>>> This commit fixes this by leaving the modalias empty for non present >>>> devices. This results in 10 modules less being loaded with a generic >>>> distro kernel config on my Cherry Trail test-device (a GPD pocket). >>> >>> >>> Well, what about hotplug? >>> >>> On some systems _STA may change from 0 to nonzero for some devices, so >>> what's going to happen to the modalias then? >> >> >> A good question. I would expect a change uevent to be generated in >> this case and when the device has become present in this new uvent the >> modalias will no longer be empty and the module will get loaded, so >> the module will not get loaded until the actual hotplug. >> >> The actual generation of this uevent should be done by the various >> subsystems based on ACPI_RECONFIG_DEVICE_ADD messages, at which point >> adev->status is already updated and then when the subsys calls >> acpi_device_uevent_modalias() for the new uevent it will return a >> non-empty modalias. > > > Rafael, how do you want to move forward with this patch ? Not sure yet, sorry. -- 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
