Message-ID: <20150317224911.GD8927@mail.corp.redhat.com>
Date:	Tue, 17 Mar 2015 18:49:11 -0400
From:	Benjamin Tissoires <benjamin.tissoires@...hat.com>
To:	Jason Gerecke <killertofu@...il.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 Mar 16 2015 or thereabouts, Jason Gerecke wrote:
> 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).
> 

Then, we could also simply add the affected devices to
usbhid/hid-quirks.c or add a quirks field in the
wacom_features struct.

On the other hand, if this only happens when there are tool left on the
tablet while no one listen, I guess we can considerate it as a corner
case and leave with it :)

Cheers,
Benjamin
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