On Mon, Apr 23, 2018, at 8:55 PM, Alex Hung wrote:
> On Mon, Apr 23, 2018 at 7:36 AM, Andy Shevchenko
> <andy.shevchenko@xxxxxxxxx> wrote:
>> On Sun, Apr 22, 2018 at 1:25 AM, Tristian Celestin
>> <tristiancelestin@xxxxxxxxxxxx> wrote:
>>
>> Thanks for the patch.
>>
>> First of all, please, include all PDx86 maintainers to the discussion as well.
>> Second, please, use `git send-email` tool to send patches, it avoids
>> attachments.
Thank you for the guidance. Will do.
>>> I am running Fedora 28 and Android-x86 on a Dell Latitude 5175 tablet. The
>>> power button functionality is driven by the intel-hid driver. I am using
>>> kernel version 4.16.
>>>
>>> Currently, the intel-hid driver does not supply a KEY_POWER up event in cases
>>> where the platform doesn't expose the 5-button array. Without this patch, the
>>> power button can't reliably respond when the platform is running Android.
>>>
>>> When running Fedora, I can use the power button to suspend and resume the
>>> tablet. I can initiate this suspend by short-pressing the power button for a
>>> second, and can resume it using another short-press.
>>>
>>> When running Android-x86, I can only short-press the power button once. After
>>> the press, the button seems to no longer respond. This is problematic when
>>> using a short-press to initiate a suspend, since a subsequent short press will
>>> not wake the tablet.
>>>
>>> I used getevent to display the KeyEvents[1] detected by Android, and a
>>> combination of 'cat /proc/kmsg' and debug statements in the intel-hid driver
>>> to display the events generated by the driver. I found the block in the intel-
>>> hid driver that generates power button events for my device. On line 253 of
>>> intel-hid.c:
>>>
>>> if (!priv->array) {
>>> if (event == 0xce) {
>>> input_report_key(priv->input_dev, KEY_POWER, 1);
>>> input_sync(priv->input_dev);
>>> return;
>>> }
>>>
>>> if (event == 0xcf)
>>> return;
>>> }
>
> Thanks for the work. This somehow sounds similar to Wacom MobileStudio
> Pro that we worked on before. A quirk was added to enable 5 button
> array, and the commit is c454a99d4ce1cebb.
>
> Could you please try to add a DMI entry in button_array_table[] and
> verify the power button again? If this works, we can use the DMI quirk
> instead.
Thank you for the guidance. I added a DMI entry to button_array_table[] for the Latitude 5175, and the
tablet now also responds to short presses while suspended.
>>>
>>> When I short-press the power button, intel-hid produces a KEY_POWER down
>>> event, but doesn't produce a KEY_POWER up event when I release the power
>>> button. Suppose intel-hid has been mapped to the input device /dev/input/
>>> event19. Then, on Android-x86, the command "getevent -lt" produces the
>>> following output:
>>>
>>> /dev/input/event19: EV_KEY KEY_POWER DOWN
>>> /dev/input/event19: EV_SYN SYN_REPORT 00000000
>>>
>>> Subsequent presses produced no output for that input device.
>>>
>>> When I added a call to input_report_key(...) and input_sync(...) on the
>>> KEY_POWER up event in the intel-hid driver, I could repeatedly short-press the
>>> power button and have Android respond appropriately, including resuming the
>>> device from suspend. My hunch as to why this is the case is that Android needs
>>> a paired KEY_POWER DOWN and UP event before it will handle the press.
>>
>> WRT, patch contents:
>> - please, do a proper commit message
>> - while it has crucial semantic mistake (missing {}) it suddenly works
>> because nothing behind the condition you had touched
>> - I would rather unify conditionals, though I would like to hear from
>> Alex and Dmitry if it's fine to do what you are trying to do in the
>> patch
>>
>> --
>> With Best Regards,
>> Andy Shevchenko
>
>
>
> --
> Cheers,
> Alex Hung
