https://bugzilla.kernel.org/show_bug.cgi?id=200983
Bug ID: 200983
Summary: Brightness hotkeys stopped working on DELL Inspiron
N4010
Product: ACPI
Version: 2.5
Kernel Version: 4.17.19
Hardware: All
OS: Linux
Tree: Mainline
Status: NEW
Severity: normal
Priority: P1
Component: Other
Assignee: [email protected]
Reporter: [email protected]
Regression: No
Brightness hotkeys worked fine with kernel version 4.17.18 on Dell Inspiron
N4010, but upgrade to version 4.17.19 broke it.
It appears that the following change fixed brightness control on some DELL
laptops while breaking it on others:
commit 587eb87b45bb6a97452b9719f63cd489e1371e77
Author: Damien Thébault <[email protected]>
Date: Wed Jul 18 12:06:01 2018 +0200
platform/x86: dell-laptop: Fix backlight detection
[ Upstream commit 2502e5a025935b7b476b69eda4959b3c4022c72b ]
Fix return code check for "max brightness" ACPI call.
The Dell laptop ACPI video brightness control is not present on dell
laptops anymore, but was present in older kernel versions.
The code that checks the return value is incorrect since the SMM
refactoring.
The old code was:
if (buffer->output[0] == 0)
Which was changed to:
ret = dell_send_request(...)
if (ret)
However, dell_send_request() will return 0 if buffer->output[0] == 0,
so we must change the check to:
if (ret == 0)
This issue was found on a Dell M4800 laptop, and the fix tested on it
as well.
Fixes: 549b4930f057 ("dell-smbios: Introduce dispatcher for SMM calls")
Signed-off-by: Damien Thébault <[email protected]>
Tested-by: Damien Thébault <[email protected]>
Reviewed-by: Pali Rohár <[email protected]>
Reviewed-by: Mario Limonciello <[email protected]>
Signed-off-by: Andy Shevchenko <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
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