From: Hector Martin <hector@marcansoft.com>
To: Zhang Rui <rui.zhang@intel.com>
Cc: Len Brown <lenb@kernel.org>,
"linux-acpi@vger.kernel.org" <linux-acpi@vger.kernel.org>
Subject: Re: [PATCH] disable _BQC/_BCQ if it returns invalid values
Date: Thu, 09 Jul 2009 03:27:23 +0200 [thread overview]
Message-ID: <4A55477B.9080909@marcansoft.com> (raw)
In-Reply-To: <1247101051.15520.194.camel@rzhang-dt>
Zhang Rui wrote:
> _BQC returns a value larger than 100?
> is this true on your laptop?
Yes, it returns random garbage. It is completely broken. There's an if()
in the ASL that disables the entire method (including no valid return
value) when a certain EC SRAM register is 0. The backlight code also
constantly clears this register. I suppose the EC should theoretically
set it at some point, but it doesn't (at least not reliably). In any
case, _BQC isn't needed here since the hardware doesn't change the
screen brightness autonomously, and disabling the method as soon as it
misbehaves works just fine.
--
Hector Martin (hector@marcansoft.com)
Public Key: http://www.marcansoft.com/marcan.asc
prev parent reply other threads:[~2009-07-09 1:27 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-07-08 20:16 [PATCH] disable _BQC/_BCQ if it returns invalid values Hector Martin
2009-07-09 0:57 ` Zhang Rui
2009-07-09 1:27 ` Hector Martin [this message]
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