Message-ID: <20150316210417.GE4053@mail.corp.redhat.com>
Date:	Mon, 16 Mar 2015 17:04:17 -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 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


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