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Message-ID: <c355258d-f207-aa5e-a170-e52438102a37@gmail.com>
Date: Wed, 31 May 2017 12:06:56 +0300
From: Oleksandr Andrushchenko <andr2000@...il.com>
To: Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc: xen-devel@...ts.xenproject.org, linux-kernel@...r.kernel.org,
linux-input@...r.kernel.org, joculator@...il.com, al1img@...il.com,
vlad.babchuk@...il.com, andrii.anisov@...il.com,
olekstysh@...il.com, boris.ostrovsky@...cle.com, jgross@...e.com,
Oleksandr Andrushchenko <oleksandr_andrushchenko@...m.com>
Subject: Re: [PATCH 2/2] xen/input: add multi-touch support
Hi, Dmitry!
On 05/30/2017 07:37 PM, Dmitry Torokhov wrote:
> On Tue, May 30, 2017 at 03:50:20PM +0300, Oleksandr Andrushchenko wrote:
>> Hi, Dmitry!
>>
>> On 05/30/2017 08:51 AM, Dmitry Torokhov wrote:
>>> On Fri, Apr 21, 2017 at 09:40:36AM +0300, Oleksandr Andrushchenko wrote:
>>>> Hi, Dmitry!
>>>>
>>>> On 04/21/2017 05:10 AM, Dmitry Torokhov wrote:
>>>>> Hi Oleksandr,
>>>>>
>>>>> On Thu, Apr 13, 2017 at 02:38:04PM +0300, Oleksandr Andrushchenko wrote:
>>>>>> From: Oleksandr Andrushchenko <oleksandr_andrushchenko@...m.com>
>>>>>>
>>>>>> Extend xen_kbdfront to provide multi-touch support
>>>>>> to unprivileged domains.
>>>>>>
>>>>>> Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@...m.com>
>>>>>> ---
>>>>>> drivers/input/misc/xen-kbdfront.c | 142 +++++++++++++++++++++++++++++++++++++-
>>>>>> 1 file changed, 140 insertions(+), 2 deletions(-)
>>>>>>
>>>>>> diff --git a/drivers/input/misc/xen-kbdfront.c b/drivers/input/misc/xen-kbdfront.c
>>>>>> index 01c27b4c3288..e5d064aaa237 100644
>>>>>> --- a/drivers/input/misc/xen-kbdfront.c
>>>>>> +++ b/drivers/input/misc/xen-kbdfront.c
>>>>>> @@ -17,6 +17,7 @@
>>>>>> #include <linux/errno.h>
>>>>>> #include <linux/module.h>
>>>>>> #include <linux/input.h>
>>>>>> +#include <linux/input/mt.h>
>>>>>> #include <linux/slab.h>
>>>>>> #include <asm/xen/hypervisor.h>
>>>>>> @@ -34,11 +35,14 @@
>>>>>> struct xenkbd_info {
>>>>>> struct input_dev *kbd;
>>>>>> struct input_dev *ptr;
>>>>>> + struct input_dev *mtouch;
>>>>>> struct xenkbd_page *page;
>>>>>> int gref;
>>>>>> int irq;
>>>>>> struct xenbus_device *xbdev;
>>>>>> char phys[32];
>>>>>> + /* current MT slot/contact ID we are injecting events in */
>>>>>> + int mtouch_cur_contact_id;
>>>>>> };
>>>>>> enum { KPARAM_X, KPARAM_Y, KPARAM_CNT };
>>>>>> @@ -47,6 +51,12 @@ module_param_array(ptr_size, int, NULL, 0444);
>>>>>> MODULE_PARM_DESC(ptr_size,
>>>>>> "Pointing device width, height in pixels (default 800,600)");
>>>>>> +enum { KPARAM_MT_X, KPARAM_MT_Y, KPARAM_MT_CNT };
>>>>>> +static int mtouch_size[KPARAM_MT_CNT] = { XENFB_WIDTH, XENFB_HEIGHT };
>>>>>> +module_param_array(mtouch_size, int, NULL, 0444);
>>>>>> +MODULE_PARM_DESC(ptr_size,
>>>>>> + "Multi-touch device width, height in pixels (default 800,600)");
>>>>>> +
>>>>> Why do you need separate module parameters for multi-touch device?
>>>> please see below
>>>>>> static int xenkbd_remove(struct xenbus_device *);
>>>>>> static int xenkbd_connect_backend(struct xenbus_device *, struct xenkbd_info *);
>>>>>> static void xenkbd_disconnect_backend(struct xenkbd_info *);
>>>>>> @@ -100,6 +110,60 @@ static irqreturn_t input_handler(int rq, void *dev_id)
>>>>>> input_report_rel(dev, REL_WHEEL,
>>>>>> -event->pos.rel_z);
>>>>>> break;
>>>>>> + case XENKBD_TYPE_MTOUCH:
>>>>>> + dev = info->mtouch;
>>>>>> + if (unlikely(!dev))
>>>>>> + break;
>>>>>> + if (unlikely(event->mtouch.contact_id !=
>>>>>> + info->mtouch_cur_contact_id)) {
>>>>> Why is this unlikely? Does contact ID changes once in 1000 packets or
>>>>> even less?
>>>> Mu assumption was that regardless of the fact that we are multi-touch
>>>> device still single touches will come in more frequently
>>>> But I can remove *unlikely* if my assumption is not correct
>>> I think the normal expectation is that "unlikely" is supposed for
>>> something that happens once in a blue moon, so I'd rather remove it.
>>>
>> agree, removed "unlikely"
>>>>>> + info->mtouch_cur_contact_id =
>>>>>> + event->mtouch.contact_id;
>>>>>> + input_mt_slot(dev, event->mtouch.contact_id);
>>>>>> + }
>>>>>> + switch (event->mtouch.event_type) {
>>>>>> + case XENKBD_MT_EV_DOWN:
>>>>>> + input_mt_report_slot_state(dev, MT_TOOL_FINGER,
>>>>>> + true);
>>> Should we establish tool event? We have MT_TOOL_PEN, etc.
>> I think that for multi-touch MT_TOOL_FINGER is enough
>> any reason we would also want MT_TOOL_PEN here?
> Why would not you? Let's say you have a drawing application running in
> guest that can make use of tool types. Why would not you want to tell it
> that the tool user is currently using is in fact a pen and not finger?
But it is a finger :) we are multi-touch, not multi pen
Besides, that, if I am about to implement pen support
(which I still not convinced we really need), how will I
do that?
My understanding is that I need 2 different slots to report
the same coordinates for finger and pen. This is because
input_mt_report_slot_state has a check that if tool has
changed for the current slot then a new tracking ID is set.
Do I also need to allocate twice more slots, so I can
report 2 * num_contacts events simultaneously (one for finger
and another for pen)?
That said, I believe we can start with multi-touch support
and if need be then add pen support as a separate change,
does that make sense for you?
>
>> (I guess MT_TOOL_PALM is not appropriate anyways)
> Depends on if you do straight pass-through from the host side or not. If
> you stack does palm rejection before passing the data through then you
> would not see MT_TOOL_PALM in guest.
the protocol used between guest and host is a generic one,
not using Linux types/constants/events.
So, no PALM/TOOL support is in place
>>>>>> + input_event(dev, EV_ABS, ABS_MT_POSITION_X,
>>>>>> + event->mtouch.u.pos.abs_x);
>>>>>> + input_event(dev, EV_ABS, ABS_MT_POSITION_Y,
>>>>>> + event->mtouch.u.pos.abs_y);
>>>>>> + input_event(dev, EV_ABS, ABS_X,
>>>>>> + event->mtouch.u.pos.abs_x);
>>>>>> + input_event(dev, EV_ABS, ABS_Y,
>>>>>> + event->mtouch.u.pos.abs_y);
>>>>>> + break;
>>>>>> + case XENKBD_MT_EV_UP:
>>>>>> + input_mt_report_slot_state(dev, MT_TOOL_FINGER,
>>>>>> + false);
>>>>>> + break;
>>>>>> + case XENKBD_MT_EV_MOTION:
>>>>>> + input_event(dev, EV_ABS, ABS_MT_POSITION_X,
>>>>>> + event->mtouch.u.pos.abs_x);
>>>>>> + input_event(dev, EV_ABS, ABS_MT_POSITION_Y,
>>>>>> + event->mtouch.u.pos.abs_y);
>>>>>> + input_event(dev, EV_ABS, ABS_X,
>>>>>> + event->mtouch.u.pos.abs_x);
>>>>>> + input_event(dev, EV_ABS, ABS_Y,
>>>>>> + event->mtouch.u.pos.abs_y);
>>>>>> + break;
>>>>>> + case XENKBD_MT_EV_SYN:
>>>>>> + input_mt_sync_frame(dev);
>>>>>> + break;
>>>>>> + case XENKBD_MT_EV_SHAPE:
>>>>>> + input_event(dev, EV_ABS, ABS_MT_TOUCH_MAJOR,
>>>>>> + event->mtouch.u.shape.major);
>>>>>> + input_event(dev, EV_ABS, ABS_MT_TOUCH_MINOR,
>>>>>> + event->mtouch.u.shape.minor);
>>>>>> + break;
>>>>>> + case XENKBD_MT_EV_ORIENT:
>>>>>> + input_event(dev, EV_ABS, ABS_MT_ORIENTATION,
>>>>>> + event->mtouch.u.orientation);
>>>>>> + break;
>>>>>> + }
>>>>>> + /* only report syn when requested */
>>>>>> + if (event->mtouch.event_type != XENKBD_MT_EV_SYN)
>>>>>> + dev = NULL;
>>>>>> }
>>>>>> if (dev)
>>>>>> input_sync(dev);
>>>>>> @@ -115,9 +179,9 @@ static int xenkbd_probe(struct xenbus_device *dev,
>>>>>> const struct xenbus_device_id *id)
>>>>>> {
>>>>>> int ret, i;
>>>>>> - unsigned int abs;
>>>>>> + unsigned int abs, touch;
>>>>>> struct xenkbd_info *info;
>>>>>> - struct input_dev *kbd, *ptr;
>>>>>> + struct input_dev *kbd, *ptr, *mtouch;
>>>>>> info = kzalloc(sizeof(*info), GFP_KERNEL);
>>>>>> if (!info) {
>>>>>> @@ -152,6 +216,17 @@ static int xenkbd_probe(struct xenbus_device *dev,
>>>>>> }
>>>>>> }
>>>>>> + touch = xenbus_read_unsigned(dev->nodename,
>>>>>> + XENKBD_FIELD_FEAT_MTOUCH, 0);
>>>>>> + if (touch) {
>>>>>> + ret = xenbus_write(XBT_NIL, dev->nodename,
>>>>>> + XENKBD_FIELD_REQ_MTOUCH, "1");
>>>>>> + if (ret) {
>>>>>> + pr_warning("xenkbd: can't request multi-touch");
>>>>>> + touch = 0;
>>>>>> + }
>>>>>> + }
>>>>>> +
>>>>>> /* keyboard */
>>>>>> kbd = input_allocate_device();
>>>>>> if (!kbd)
>>>>>> @@ -208,6 +283,67 @@ static int xenkbd_probe(struct xenbus_device *dev,
>>>>>> }
>>>>>> info->ptr = ptr;
>>>>>> + /* multi-touch device */
>>>>>> + if (touch) {
>>>>>> + int num_cont, width, height;
>>>>>> +
>>>>>> + mtouch = input_allocate_device();
>>>>>> + if (!mtouch)
>>>>>> + goto error_nomem;
>>>>>> +
>>>>>> + num_cont = xenbus_read_unsigned(info->xbdev->nodename,
>>>>>> + XENKBD_FIELD_MT_NUM_CONTACTS,
>>>>>> + 1);
>>> Should we refuse MT devices with number of contacts less than 2?
>> we can, but I see no harm in 1. what is more, this may
>> allow guests to emulate more pointing devices
>> but, if you insist, then I will add appropriate code to
>> reject if number of contacts is less then 2
>>>>>> + width = xenbus_read_unsigned(info->xbdev->nodename,
>>>>>> + XENKBD_FIELD_MT_WIDTH,
>>>>>> + XENFB_WIDTH);
>>>>>> + height = xenbus_read_unsigned(info->xbdev->nodename,
>>>>>> + XENKBD_FIELD_MT_HEIGHT,
>>>>>> + XENFB_HEIGHT);
>>>>> Curious why you need separate parameters here too...
>>>> This is because mt parameters are different from ptr
>>>> in a way that they are configurable per front driver's
>>>> instance rather than per backend, e.g. in XenStore:
>>>>
>>>> /local/domain/0/backend/vkbd/1/0/width = "1920"
>>>> /local/domain/0/backend/vkbd/1/0/height = "1080"
>>>>
>>>> /local/domain/1/device/vkbd/0/multi-touch-width = "1920"
>>>> /local/domain/1/device/vkbd/0/multi-touch-height = "1080"
>>>> /local/domain/1/device/vkbd/0/multi-touch-num-contacts = "10"
>>>>
>>>> /local/domain/1/device/vkbd/1/multi-touch-width = "800"
>>>> /local/domain/1/device/vkbd/1/multi-touch-height = "600"
>>>> /local/domain/1/device/vkbd/1/multi-touch-num-contacts = "3"
>>>>
>>>> The main reason for such configuration is that you can
>>>> configure multiple mt input devices even for the same guest
>>>> with different resolutions which may not match those
>>>> configured for ptr.
>>>> (In my use-case I use new displif protocol [1] in conjunction
>>>> with mt input devices and the corresponding backend is not
>>>> QEMU's xenfb)
>>> I see.
>>>
>>>> As to module parameters, I added those to be consistent with
>>>> ptr device. Do you think we can live without them and
>>>> do you want me to remove them?
>>> Yes, I think we better. I am also confused by the way you are handling
>>> the module parameters. It looks to me you update them with data passed
>> >from the backend, but never use the data...
>> I have removed module parameters (the only use of those
>> was to be able to see configured width and height on
>> guest side, but this is minor)
> evtest would show it to you. Or you can query input device yourself
> (EVIOCGABS iotcl).
yes, if embedded system (which is my target) has evtest
but it definitely does have ioctl though
>>>>>> +
>>>>>> + mtouch->name = "Xen Virtual Multi-touch";
>>>>>> + mtouch->phys = info->phys;
>>>>>> + mtouch->id.bustype = BUS_PCI;
>>>>>> + mtouch->id.vendor = 0x5853;
>>>>>> + mtouch->id.product = 0xfffd;
>>>>>> +
>>>>>> + __set_bit(EV_ABS, mtouch->evbit);
>>>>>> + __set_bit(EV_KEY, mtouch->evbit);
>>>>>> + __set_bit(BTN_TOUCH, mtouch->keybit);
> Please make it
> input_set_capability(mtouch, EV_KEY, BTN_TOUCH);
>
> and drop all __set_bit()s.
done, thank you
>>>>>> +
>>>>>> + input_set_abs_params(mtouch, ABS_X,
>>>>>> + 0, width, 0, 0);
>>>>>> + input_set_abs_params(mtouch, ABS_Y,
>>>>>> + 0, height, 0, 0);
>>>>>> + input_set_abs_params(mtouch, ABS_PRESSURE,
>>>>>> + 0, 255, 0, 0);
>>>>>> +
>>>>>> + input_set_abs_params(mtouch, ABS_MT_TOUCH_MAJOR,
>>>>>> + 0, 255, 0, 0);
>>>>>> + input_set_abs_params(mtouch, ABS_MT_POSITION_X,
>>>>>> + 0, width, 0, 0);
>>>>>> + input_set_abs_params(mtouch, ABS_MT_POSITION_Y,
>>>>>> + 0, height, 0, 0);
>>>>>> + input_set_abs_params(mtouch, ABS_MT_PRESSURE,
>>>>>> + 0, 255, 0, 0);
>>>>>> +
>>>>>> + input_mt_init_slots(mtouch, num_cont, 0);
>>> We need error handling here.
>> done
>>> Also, it would be nice if we set INPUT_MT_*
>>> flags here, so that userspace had better chance of figuring how to
>>> handle the device.
>> done, I will use INPUT_MT_DIRECT | INPUT_MT_DROP_UNUSED
> Does that mean that your backend does not reliably report release of
> contacts?
there is a ring buffer between host and guest,
so there is always a possibility (rather small I believe)
that the buffer overruns. Do you think I need INPUT_MT_DROP_UNUSED or
we can live without it?
>
> Thanks.
>
>>>>>> +
>>>>>> + mtouch_size[KPARAM_MT_X] = width;
>>>>>> + mtouch_size[KPARAM_MT_Y] = height;
>>>>>> + info->mtouch_cur_contact_id = -1;
>>>>>> +
>>>>>> + ret = input_register_device(mtouch);
>>>>>> + if (ret) {
>>>>>> + input_free_device(mtouch);
>>>>>> + xenbus_dev_fatal(info->xbdev, ret,
>>>>>> + "input_register_device(mtouch)");
>>>>>> + goto error;
>>>>>> + }
>>>>>> + info->mtouch_cur_contact_id = -1;
>>>>>> + info->mtouch = mtouch;
>>>>>> + }
>>>>>> +
>>>>>> ret = xenkbd_connect_backend(dev, info);
>>>>>> if (ret < 0)
>>>>>> goto error;
>>>>>> @@ -240,6 +376,8 @@ static int xenkbd_remove(struct xenbus_device *dev)
>>>>>> input_unregister_device(info->kbd);
>>>>>> if (info->ptr)
>>>>>> input_unregister_device(info->ptr);
>>>>>> + if (info->mtouch)
>>>>>> + input_unregister_device(info->mtouch);
>>>>>> free_page((unsigned long)info->page);
>>>>>> kfree(info);
>>>>>> return 0;
>>>>>> --
>>>>>> 2.7.4
>>>>>>
>>> Thanks.
>>>
>> For your convenience I am attaching the changes I am about
>> to put into v1 of the series:
>> - remove unlikely
>> - remove module parameters
>> - error handling for input_mt_init_slots
>> - let userspace better chance of figuring how to handle the device
>>
>> Thank you,
>> Oleksandr
>> From e76506c55846e2bb4ccbafa430642e368643e51d Mon Sep 17 00:00:00 2001
>> From: Oleksandr Andrushchenko <oleksandr_andrushchenko@...m.com>
>> Date: Tue, 30 May 2017 14:49:58 +0300
>> Subject: [PATCH] Fix: remove unlikely Fix: remove module paramters Fix: error
>> handling for input_mt_init_slots Fix: let userspace better chance of figuring
>> how to handle the device
>>
>> Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@...m.com>
>> ---
>> drivers/input/misc/xen-kbdfront.c | 21 ++++++++++-----------
>> 1 file changed, 10 insertions(+), 11 deletions(-)
>>
>> diff --git a/drivers/input/misc/xen-kbdfront.c b/drivers/input/misc/xen-kbdfront.c
>> index 8266ef948a06..273d786a19cd 100644
>> --- a/drivers/input/misc/xen-kbdfront.c
>> +++ b/drivers/input/misc/xen-kbdfront.c
>> @@ -51,12 +51,6 @@ module_param_array(ptr_size, int, NULL, 0444);
>> MODULE_PARM_DESC(ptr_size,
>> "Pointing device width, height in pixels (default 800,600)");
>>
>> -enum { KPARAM_MT_X, KPARAM_MT_Y, KPARAM_MT_CNT };
>> -static int mtouch_size[KPARAM_MT_CNT] = { XENFB_WIDTH, XENFB_HEIGHT };
>> -module_param_array(mtouch_size, int, NULL, 0444);
>> -MODULE_PARM_DESC(ptr_size,
>> - "Multi-touch device width, height in pixels (default 800,600)");
>> -
>> static int xenkbd_remove(struct xenbus_device *);
>> static int xenkbd_connect_backend(struct xenbus_device *, struct xenkbd_info *);
>> static void xenkbd_disconnect_backend(struct xenkbd_info *);
>> @@ -114,8 +108,8 @@ static irqreturn_t input_handler(int rq, void *dev_id)
>> dev = info->mtouch;
>> if (unlikely(!dev))
>> break;
>> - if (unlikely(event->mtouch.contact_id !=
>> - info->mtouch_cur_contact_id)) {
>> + if (event->mtouch.contact_id !=
>> + info->mtouch_cur_contact_id) {
>> info->mtouch_cur_contact_id =
>> event->mtouch.contact_id;
>> input_mt_slot(dev, event->mtouch.contact_id);
>> @@ -327,10 +321,15 @@ static int xenkbd_probe(struct xenbus_device *dev,
>> input_set_abs_params(mtouch, ABS_MT_PRESSURE,
>> 0, 255, 0, 0);
>>
>> - input_mt_init_slots(mtouch, num_cont, 0);
>> + ret = input_mt_init_slots(mtouch, num_cont,
>> + INPUT_MT_DIRECT | INPUT_MT_DROP_UNUSED);
>> + if (ret) {
>> + input_free_device(mtouch);
>> + xenbus_dev_fatal(info->xbdev, ret,
>> + "input_mt_init_slots");
>> + goto error;
>> + }
>>
>> - mtouch_size[KPARAM_MT_X] = width;
>> - mtouch_size[KPARAM_MT_Y] = height;
>> info->mtouch_cur_contact_id = -1;
>>
>> ret = input_register_device(mtouch);
>> --
>> 2.7.4
>>
>
Thank you,
Oleksandr
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