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Date:   Fri, 5 May 2017 07:45:59 +0300
From:   Oleksandr Andrushchenko <andr2000@...il.com>
To:     Oleksandr Andrushchenko <andr2000@...il.com>,
        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
Subject: Re: [PATCH 2/2] xen/input: add multi-touch support

Hi, Dmitry!

On 04/21/2017 09:40 AM, 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
>>> + 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
>

As all the dependencies are now merged into the kernel and *if*
the above sounds reasonable for you can we please proceed with this patch?

Thank you,
Oleksandr

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