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Date:   Fri, 21 Apr 2017 09:40:36 +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 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
>> +				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);
>> +				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);
>> +		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)

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?
>> +
>> +		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);
>> +
>> +		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);
>> +
>> +		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.
Thank you,
Oleksandr
[1] 
https://git.kernel.org/pub/scm/linux/kernel/git/xen/tip.git/commit/?h=for-linus-4.12&id=e27c533dc4d0338266ccb6dab428150d4d629e6a

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