On Sun, Jan 22, 2017 at 12:49 AM, Hans de Goede [off-list ref] wrote:

Hi,

On 21-01-17 20:13, Dmitry Torokhov wrote:

quoted

On Mon, Jan 09, 2017 at 06:57:06PM +0100, Hans de Goede wrote:

quoted

On some tablets using the soc_button_array driver the buttons do not
follow the standard home, power, volume_up, volume_down, rotation_lock
button order as published by Microsoft.

We can use the existing udev hwdb mechanism to fix this up, but then
the created devices must have a unique name, therefor this commit adds
a unique name for the 2 created gpio-keys input devices.

Why does it have to have unique name? You should be able to match on
other input device properties, for example ATTR{capabilities/ev} or
ATTR{capabilities/keys} to identify the device you want to adjust.

hwdb entries do not have access to full udev data, basically there
are 2 match formats:

# Supported hardware matches are:
#  - Generic input devices match:
#      evdev:input:bZZZZvYYYYpXXXXeWWWW-VVVV
#    This matches on the kernel modalias of the input-device, mainly:
#    ZZZZ is the bus-id (see /usr/include/linux/input.h BUS_*), YYYY, XXXX
and
#    WWW are the 4-digit hex uppercase vendor, product and version ID and
VVVV
#    is an arbitrary length input-modalias describing the device
capabilities.
#    The vendor, product and version ID for a device node "eventX" is listed
#    in /sys/class/input/eventX/device/id.
#
#  - Input driver device name and DMI data match:
#      evdev:name:<input device name>:dmi:bvn*:bvr*:bd*:svn<vendor>:pn*
#    <input device name> is the name device specified by the
#    driver, <vendor> is the firmware-provided string exported
#    by the kernel DMI modalias, see /sys/class/dmi/id/modalias


Since we want to match on DMI info we need to use the second, and
the info you are referring to is not available here.

Well, you can either teach hwdb new tricks or mangle the name in udev
rule. As far as I can see the original invocation is:

# device matching the input device name and the machine's DMI data
KERNELS=="input*", IMPORT{builtin}="hwdb
'evdev:name:$attr{name}:$attr{[dmi/id]modalias}'", \
 RUN{builtin}+="keyboard", GOTO="evdev_end"

You can add a similar rule that also looks at ATTR{whatever}, but
instead of using "name:$attr{name}" you can use whatever string you
want.

There is no need to change kernel, it already exports all necessary data.

Thanks.

-- 
Dmitry