From: Andrey Borzenkov <arvidjaar@mail.ru>
To: "Rafael J. Wysocki" <rjw@sisk.pl>, Zhao Yakui <yakui.zhao@intel.com>
Cc: linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: rc6+ regression - backlight reset to 0 on boot after 7c0ea45be4f114d85ee35caeead8e1660699c46f
Date: Wed, 2 Apr 2008 22:53:15 +0400 [thread overview]
Message-ID: <200804022253.17862.arvidjaar@mail.ru> (raw)
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Commit 7c0ea45be4f114d85ee35caeead8e1660699c46f registers ACPI backlight
even if _BQC method (query current backlight level) is missing. The effect is:
during initialization video.c:acpi_video_device_find_cap() calls backlight_update_status(). It tries to fetch actual level via acpi_video_get_brightness() - but as _BQC is missing it just returns current value
as stored in memory - i.e. zero, because it was never set. So effectively
backlight_update_status() reset brightness to minimal value == 0.
This happens on Toshiba Portege 4000. Verified by reverting commit on top of
rc8.
On a side note, it would be nice to fit backlight device into actual ACPI
device tree instead of /devices/virtual.
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next reply other threads:[~2008-04-02 18:53 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-04-02 18:53 Andrey Borzenkov [this message]
2008-04-03 1:59 ` rc6+ regression - backlight reset to 0 on boot after 7c0ea45be4f114d85ee35caeead8e1660699c46f Zhao Yakui
2008-04-03 18:34 ` Andrey Borzenkov
2008-04-08 6:05 ` Thomas Renninger
-- strict thread matches above, loose matches on Subject: below --
2008-04-03 22:49 2.6.25-rc8-git2: Reported regressions from 2.6.24 Rafael J. Wysocki
2008-04-03 23:22 ` rc6+ regression - backlight reset to 0 on boot after 7c0ea45be4f114d85ee35caeead8e1660699c46f Rafael J. Wysocki
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