Hi, Recently I saw two bugs about acer system: https://bugzilla.kernel.org/show_bug.cgi?id=35622 https://bugzilla.kernel.org/show_bug.cgi?id=51051 The backlight is handled by gpu driver's backlight interface, and hotkey is handled by acpi video driver. The problem is, hotkey notification does not function on these systems now. The reason is, acer-wmi driver will unload acpi video driver when it found these systems are in its video_vendor_dmi_table, which is used to keep all the systems that are known having buggy acpi video interface implementations. So we have a problem here, though acpi video driver can't handle backlight level change, it is still required to handle hotkey notificaions, and thus unload the driver is not desired. One way to solve this problem is, to have acpi video driver deal with these broken systems that it can not handle by itself: not create backlight interface while still keeping the notification handler there. To achieve this, we need to move those systems listed in video_vendor_dmi_table to video_detect_dmi_table, and we are done. And any code to touch acpi video driver in acer-wmi driver can be removed, also no need to add SELECT ACPI_VIDEO to CONFIG_ACER_WMI. The downside is, if other platform vendor drivers all follow this rule, we will end up with a big video_detect_dmi_table. Another way is to add a new interface, something like acpi_video_unregister_backlight, to let platform drivers call. And this new interface will only unregister the backlight device acpi video driver has already created and nothing more. So the notification handler of acpi video driver will stay, solving the problem. The downside is, it's kind of odd to let another module solve a problem for acpi video module. In this case, the vendor driver's whole point is to unregister acpi video driver's backlight interface, while it does't handle backlight nor hotkey. So it doesn't seem to be required in this game. Please feel free to share your opinion, which one you prefer or some new idea perhaps. Thanks, Aaron -- 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
