Date: Wed, 19 Nov 2014 17:05:47 +0100
From: Wolfram Sang <wsa@the-dreams.de>
To: Lan Tianyu <tianyu.lan@intel.com>
Cc: rjw@rjwysocki.net, lenb@kernel.org, robert.moore@intel.com,
        lv.zheng@intel.com, shigorin@gmail.com, adamw@happyassassin.net,
        jan.brummer@tabos.org, linux-acpi@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-i2c@vger.kernel.org,
        devel@acpica.org
Subject: Re: [PATCH] ACPI: Add _DEP(Operation Region Dependencies) support to
 fix battery issue on the Asus T100TA
Message-ID: <20141119160547.GA8557@katana>
References: <1416410441-14425-1-git-send-email-tianyu.lan@intel.com>
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On Wed, Nov 19, 2014 at 11:20:41PM +0800, Lan Tianyu wrote:
> ACPI 5.0 introduces _DEP to designate device objects that OSPM should
> assign a higher priority in start ordering due to future operation region
> accesses.
>=20
> On Asus T100TA, ACPI battery info are read from a I2C slave device via
> I2C operation region. Before I2C operation region handler is installed,
> battery _STA always returns 0. There is a _DEP method of designating
> start order under battery device node.
>=20
> This patch is to implement _DEP feature to fix battery issue on the Asus =
T100TA.
> Introducing acpi_dep_list and adding dep_unmet count in the struct
> acpi_device. During ACPI namespace scan, create struct acpi_dep_data for a
> valid pair of master (device pointed to by _DEP)/slave(device with _DEP),=
 record
> master's and slave's ACPI handle in it and put it into acpi_dep_list. The=
 dep_unmet
> count will increase by one if there is a device under its _DEP. Driver's =
probe() should
> return EPROBE_DEFER when find dep_unmet larger than 0. When I2C operation
> region handler is installed, remove all struct acpi_dep_data on the acpi_=
dep_list
> whose master is pointed to I2C host controller and decrease slave's dep_u=
nmet.
> When dep_unmet decreases to 0, all _DEP conditions are met and then do ac=
pi_bus_attach()
> for the device in order to resolve battery _STA issue on the Asus T100TA.
>=20
> Reference: https://bugzilla.kernel.org/show_bug.cgi?id=3D69011=20
> Tested-by: Jan-Michael Brummer <jan.brummer@tabos.org>
> Tested-by: Adam Williamson <adamw@happyassassin.net>
> Tested-by: Michael Shigorin <shigorin@gmail.com>
> Signed-off-by: Lan Tianyu <tianyu.lan@intel.com>

As long as the I2C related changes are that minimal:

Acked-by: Wolfram Sang <wsa@the-dreams.de> for the I2C part


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