[PATCH v3 4/4] thinkpad-acpi: fix handle locate for video and query of _BCL
Henrique de Moraes Holschuh
hmh at hmh.eng.br
Fri Sep 27 08:16:59 PDT 2013
On Thu, 26 Sep 2013, Aaron Lu wrote:
> I checked the git log for the commit to use tpacpi_acpi_handle_locate to
> locate video controller's ACPI handle, it's:
> commit 122f26726b5e16174bf8a707df14be1d93c49d62
> Author: Henrique de Moraes Holschuh <hmh at hmh.eng.br>
> Date: Mon Aug 9 23:48:18 2010 -0300
> So I checked out that commit and found that it shouldn't work either,
> since it has the same problem of the current code.
> The ACPI video controller device is given an id of ACPI_VIDEO_HID, but
> it's only known to Linux ACPI, not ACPICA, so the function provided by
> ACPICA acpi_get_devices will not work in this case, as that function will
> really check the control method of _HID under the handle, which does not
> exist no matter if Linux ACPI has added an id to its device structure or
> not. OTOH, the function provided by Linux ACPI acpi_device_hid will see
> the added id. In a word, the add of the HID will not affect the ASL
> namespace layout of the device node(thus, no _HID control method will
> be added to the device node).
Erk. It went broken for a long time, and the users didn't notice(!)...
> commit ff413195e830541afeae469fc866ecd0319abd7e
> Author: Alex Hung <alex.hung at canonical.com>
> Date: Tue Apr 24 16:40:52 2012 +0800
> thinkpad-acpi: fix issuing duplicated key events for brightness up/down
> The tp_features.bright_acpimode will not be set correctly for brightness
> control because ACPI_VIDEO_HID will not be located in ACPI. As a result,
> a duplicated key event will always be sent. acpi_video_backlight_support()
> is sufficient to detect standard ACPI brightness control.
> Signed-off-by: Alex Hung <alex.hung at canonical.com>
> Signed-off-by: Matthew Garrett <mjg at redhat.com>
Until that. And unfortunately I did not connect the dots at the time.
Thanks for explaining the issue properly.
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