Date:	Mon, 16 Mar 2015 15:36:29 -0700
From:	Jason Gerecke <killertofu@...il.com>
To:	Benjamin Tissoires <benjamin.tissoires@...hat.com>
CC:	Jiri Kosina <jkosina@...e.cz>, Ping Cheng <pinglinux@...il.com>,
	Linux Input <linux-input@...r.kernel.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] HID: wacom: ask for a in-prox report when it was missed

On 3/16/2015 2:04 PM, Benjamin Tissoires wrote:
> On Mar 16 2015 or thereabouts, Jason Gerecke wrote:
>> On 3/16/2015 12:27 PM, Benjamin Tissoires wrote:
>>> On Mar 16 2015 or thereabouts, Jason Gerecke wrote:
>>>> On 3/16/2015 7:50 AM, Jiri Kosina wrote:
>>>>> On Thu, 5 Mar 2015, Benjamin Tissoires wrote:
>>>>>
>>>>>> If noone listens to the input device when a tool comes in proximity,
>>>>>> the tablet does not send the in-prox event when a client becomes available.
>>>>>> That means that no events will be sent until the tool is taken out of
>>>>>> proximity.
>>>>>>
>>>>>> In this situation, ask for the report WACOM_REPORT_INTUOSREAD which will
>>>>>> read the corresponding feature and generate an in-prox event.
>>>>>> To make some generation of hardware working, we need to unset the
>>>>>> quirk NO_GET set by hid-core because the interfaces are seen as "boot
>>>>>> mouse".
>>>>>>
>>>>>> We don't schedule this read in a worker while we are in an IO interrupt.
>>>>>> We know that usbhid will do it asynchronously. If this is triggered by
>>>>>> uhid, then this is obviously a client side bug :)
>>>>>>
>>>>>> Signed-off-by: Benjamin Tissoires <benjamin.tissoires@...hat.com>
>>>>>
>>>>> Ping, Jason, I'd like to get your Ack on this before pushing this through
>>>>> if possible.
>>>>>
>>>>> Thanks.
>>>>>
>>>>
>>>> This update seems to have solved the issue I was having earlier. I do
>>>> still see some weird behavior with the Intuos3 though. For whatever
>>>> reason, if a tool is in prox and no client is connected, the device
>>>> will repeatedly connect and disconnect from the bus. For example,
>>>> while sitting at a VT after connecting the device:
>>>>
>>>> [  209.890431] usb 2-1.5.4: new full-speed USB device number 10 using ehci-pci
>>>> [  209.992189] input: Wacom Intuos3 6x8 as
>>>> /devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.5/2-1.5.4/2-1.5.4:1.0/0003:056A:00B1.0009/input/input26
>>>> [  209.992475] input: Wacom Intuos3 6x8 Pad as
>>>> /devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.5/2-1.5.4/2-1.5.4:1.0/0003:056A:00B1.0009/input/input27
>>>> [  209.992846] wacom 0003:056A:00B1.0009: hidraw4: USB HID v1.00 Mouse
>>>> [Tablet PTZ-630] on usb-0000:00:1d.0-1.5.4/input0
>>>> [  213.022545] usb 2-1.5.4: USB disconnect, device number 10
>>>> [  213.344055] usb 2-1.5.4: new full-speed USB device number 11 using ehci-pci
>>>> [  213.445779] input: Wacom Intuos3 6x8 as
>>>> /devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.5/2-1.5.4/2-1.5.4:1.0/0003:056A:00B1.000A/input/input28
>>>> [  213.446185] input: Wacom Intuos3 6x8 Pad as
>>>> /devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.5/2-1.5.4/2-1.5.4:1.0/0003:056A:00B1.000A/input/input29
>>>> [  213.446703] wacom 0003:056A:00B1.000A: hidraw4: USB HID v1.00 Mouse
>>>> [Tablet PTZ-630] on usb-0000:00:1d.0-1.5.4/input0
>>>> [  214.815925] usb 2-1.5.4: USB disconnect, device number 11
>>>> [  215.246142] usb 2-1.5.4: new full-speed USB device number 12 using ehci-pci
>>>>
>>>> [ ... and so on ...]
>>>>
>>>> It makes using the device from a VT difficult (e.g. for debugging),
>>>> but in the typical case where X is started shortly after boot and
>>>> hotplugs devices as soon as they're available it shouldn't pose a
>>>> problem. If Benjamin has any ideas I'd like to hear them, but in the
>>>> meantime I'm comfortable seeing this go upstream:
>>>
>>> HID_QUIRK_ALWAYS_POLL :)
>>>
>>> Some usb devices do not like to not be polled and keep
>>> disconnecting/reconnecting. Looks like the Intuos 3 is one of them.
>>> The only cons are that the device won't save power when no one is reading
>>> the inputs. Not sure if that is a requirement for Wacom tablets though.
>>>
>>> Note that HID_QUIRK_ALWAYS_POLL should make this patch useless in these
>>> cases, the kernel will keep track of the current device because it will
>>> receive the events.
>>>
>>>>
>>>> Acked-by: Jason Gerecke <killertofu@...il.com>
>>>
>>> Thanks!
>>>
>>> Cheers,
>>> Benjamin
>>>
>>
>> That does indeed seem to solve the Intuos3 weirdness :)
>>
>> Saving power is a big deal for ISDv4/5 sensors where it has a direct impact
>> on runtime. If setting HID_QURIK_ALWAYS_POLL e.g. disables USB selective
>> suspend then that'd be an issue. However, if it simply causes the kernel to
>> respond to events even if nobody is listening then it'd probably be similar
>> to the situation when we were under drivers/input.
>>
>> I'm inclined to say we should target that quirk at only those devices that
>> need it since I know tablet PC manufacturers go to quite some lengths to
>> minimize every mA of unnecessary current draw from the batteries.
>>
>
> Just a thought, but it looks like the problematic generation have the
> QUIRK_NO_GET set by hid-core (boot interface). If you are on it, could I
> ask you to test to set HID_QUIRK_ALWAYS_POLL and unset HID_QUIRK_NO_GET
> only if HID_QUIRK_NO_GET was set?
>
> IIRC, there was no problems on the Intuos 4+ with the USB suspend, so
> maybe that trick would be enough.
>
> Cheers,
> Benjamin
>
>

I'm not sure that'll be enough. Most of our devices use a boot mouse 
interface, even some that work fine using the default quirks (e.g. 
Cintiq 24HDT). On the tablet PC side of the world, it looks like its a 
crapshoot whether the sensor will have a boot mouse collection or 
something else (though I haven't yet checked to see how they react to 
having a pen in prox without a client).

-- 
Jason
---
Now instead of four in the eights place /
you’ve got three, ‘Cause you added one /
(That is to say, eight) to the two, /
But you can’t take seven from three, /
So you look at the sixty-fours....
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