Re: [PATCH] ACPI / PM: Traverse video_device_list for backlight restoration

[Matthias Hopf <mhopf@suse.de>]

A bit of background about this patch:


acpi_video_bus_get_devices() explicitly calls acpi_video_device_enumerate()
before acpi_video_bus_get_one_device(), which does acpi_video_device_bind().

In _enumerate(), active_list[] is created, with .bind_info explicitly set to
NULL, while the related .bind_info entry in video_device_list is set to the
acpi_video_device ptr in _bind().

The .bind_info is later used in acpi_video_resume() to re-set the backlight
- but it's only evaluated on the active_list[], on which all .bind_info are
NULL by construction.  This results in backlight not being restored, if the
BIOS doesn't do this by itself already.


The patch resolves this by replacing the active_list[] traversal by a
video_device_list traversal, but due to the nature of the issue I'm unsure
whether the original issue isn't of more principal quality.  I don't understand
why the list is (partially) transformed into an array in the first place,
especially as both the array *and* the list are used in the code...


Thanks

Matthias

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Matthias Hopf <mhopf@suse.de>      __        __   __
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