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Re: [Xen-devel] [PATCH 2/2] xen/kbdif: add multi-touch support


On 01/07/2017 12:37 AM, Stefano Stabellini wrote:

On Fri, 6 Jan 2017, Oleksandr Andrushchenko wrote:

From: Oleksandr Andrushchenko <Oleksandr_Andrushchenko@xxxxxxxx>

Signed-off-by: Oleksandr Andrushchenko <Oleksandr_Andrushchenko@xxxxxxxx>
---
  xen/include/public/io/kbdif.h | 228 ++++++++++++++++++++++++++++++++++++++++++
  1 file changed, 228 insertions(+)

diff --git a/xen/include/public/io/kbdif.h b/xen/include/public/io/kbdif.h
index 0e19a40..1b446f9 100644
--- a/xen/include/public/io/kbdif.h
+++ b/xen/include/public/io/kbdif.h
@@ -57,6 +57,12 @@
   *      Backends, which support reporting of absolute coordinates for pointer
   *      device should set this to 1.
   *
+ * feature-multi-touch
+ *      Values:         <uint>
+ *
+ *      Backends, which support reporting of multi-touch events
+ *      should set this to 1.
+ *
   *------------------------- Pointer Device Parameters ------------------------
   *
   * width
@@ -87,6 +93,11 @@
   *      Request from backend to report absolute pointer coordinates
   *      (XENKBD_TYPE_POS) instead of relative ones (XENKBD_TYPE_MOTION).
   *
+ * request-multi-touch
+ *      Values:         <uint>
+ *
+ *      Request from backend to report multi-touch events.

I think in English should be "request backend to report multi-touch
events". Same above.

Done



+ *
   *----------------------- Request Transport Parameters -----------------------
   *
   * event-channel
@@ -107,6 +118,43 @@
   *      OBSOLETE, not recommended for use.
   *      A unique (within the guest domain given) value identifying event
   *      channel and page reference pair.
+ *
+ *----------------------- Multi-touch Device Parameters -----------------------
+ *
+ * Every multi-touch input device uses a dedicated event ring and is

For clarity I would say "Every multi-touch input device uses a dedicated
frontend/backend connection". That includes a ring, an event channel,
and xenstore entries.


Done

+ * configured via XenStore properties under XENKBD_PATH_MTOUCH folder.

I don't understand why we need a new xenstore folder. Why do we need
XENKBD_PATH_MTOUCH?

This is just another (IMO, cleaner) approach to define
properties in XenStore for multiple instances.
Let's see what vif does on my PC:
/local/domain/11/device/vif/0/queue-0/tx-ring-ref = "2304"
...
/local/domain/11/device/vif/0/queue-1/tx-ring-ref = "2306"
...
/local/domain/11/device/vif/0/queue-2/tx-ring-ref = "2308"
...
/local/domain/11/device/vif/0/queue-3/tx-ring-ref = "2310"
...
/local/domain/11/device/vif/0/request-rx-copy = "1"

We have folders "queue-%d" per queue which in my case are

under XENKBD_PATH_MTOUCH.

/local/domain/11/device/vkbd/0/mtouch/0/width = "3200"
/local/domain/11/device/vkbd/0/mtouch/0/height = "3200"
/local/domain/11/device/vkbd/0/mtouch/0/num-contacts = "5"
/local/domain/11/device/vkbd/0/mtouch/1/width = "6400"
/local/domain/11/device/vkbd/0/mtouch/1/height = "6400"
/local/domain/11/device/vkbd/0/mtouch/1/num-contacts = "10"

Namely, instead of "mtouch-%d" I use "mtouch/%d/.
This is just like using "/local/domain/%d" but not
"/local/domain-%d", so "mtouch/%d" seem to be more
consistent.



+ * The values below are per emulated multi-touch input device:
+ *
+ * num-contacts
+ *      Values:         <uint>
+ *
+ *      Number of simultaneous touches reported.
+ *
+ * width
+ *      Values:         <uint>
+ *
+ *      Width of the touch area to be used by the frontend
+ *      while reporting input events, pixels, [0; UINT32_MAX].
+ *
+ * height
+ *      Values:         <uint>
+ *
+ *      Height of the touch area to be used by the frontend
+ *      while reporting input events, pixels, [0; UINT32_MAX].

This is OK.



+ *----------------------- Multi-touch Transport Parameters --------------------
+ *
+ * event-channel
+ *      Values:         <uint>
+ *
+ *      The identifier of the Xen event channel used to signal activity
+ *      in the ring buffer.
+ *
+ * page-gref
+ *      Values:         <uint>
+ *
+ *      The Xen grant reference granting permission for the backend to map
+ *      a sole page in a single page sized event ring buffer.
   */

No need for this. If request-multi-touch, the usual xenkbd ring will be
used for multi touch events. We can use the event-channel and page-gref
already specified under "Request Transport Parameters".

Ok, will remove
/* 
@@ -117,6 +165,16 @@
  #define XENKBD_TYPE_RESERVED           2
  #define XENKBD_TYPE_KEY                3
  #define XENKBD_TYPE_POS                4
+#define XENKBD_TYPE_MTOUCH             5
+
+/* Multi-touch event sub-codes */
+
+#define XENKBD_MT_EV_DOWN              0
+#define XENKBD_MT_EV_UP                1
+#define XENKBD_MT_EV_MOTION            2
+#define XENKBD_MT_EV_SYN               3
+#define XENKBD_MT_EV_SHAPE             4
+#define XENKBD_MT_EV_ORIENT            5
/* 
   * CONSTANTS, XENSTORE FIELD AND PATH NAME STRINGS, HELPERS.
@@ -125,11 +183,17 @@
  #define XENKBD_DRIVER_NAME             "vkbd"
#define XENKBD_FIELD_FEAT_ABS_POINTER "feature-abs-pointer" 
+#define XENKBD_FIELD_FEAT_MTOUCH       "feature-multi-touch"
  #define XENKBD_FIELD_REQ_ABS_POINTER   "request-abs-pointer"
+#define XENKBD_FIELD_REQ_MTOUCH        "request-multi-touch"
  #define XENKBD_FIELD_RING_GREF         "page-gref"
  #define XENKBD_FIELD_EVT_CHANNEL       "event-channel"
  #define XENKBD_FIELD_WIDTH             "width"
  #define XENKBD_FIELD_HEIGHT            "height"
+#define XENKBD_FIELD_NUM_CONTACTS      "num-contacts"
+
+/* Path entries */
+#define XENKBD_PATH_MTOUCH             "mtouch"
/* OBSOLETE, not recommended for use */ 
  #define XENKBD_FIELD_RING_REF          "page-ref"
@@ -249,6 +313,170 @@ struct xenkbd_position
      int32_t rel_z;
  };
+/* 
+ * Multi-touch event and its sub-types
+ *
+ * All multi-touch event packets have common header:
+ *
+ *          0                 1                  2                3        
octet
+ * +-----------------+-----------------+-----------------+-----------------+
+ * |  _TYPE_MTOUCH   |    event_type   |    contact_id   |     reserved    |
+ * +-----------------+-----------------+-----------------+-----------------+
+ * |                               reserved                                |
+ * +-----------------+-----------------+-----------------+-----------------+

Given that the structs are all of the same size, shouldn't there be more
reserved bytes here?

why? The common part is:
struct xenkbd_mtouch {
    uint8_t type;             /* XENKBD_TYPE_MTOUCH */
    uint8_t event_type;       /* XENKBD_MT_EV_??? */
    uint8_t contact_id;
    uint8_t reserved[5];      /* reserved for the future use */
    union {



+ * event_type - unt8_t, multi-touch event sub-type, XENKBD_MT_EV_???
+ * contact_id - unt8_t, ID of the contact
+ *
+ * Touch interactions can consist of one or more contacts.
+ * For each contact, a series of events is generated, starting
+ * with a down event, followed by zero or more motion events,
+ * and ending with an up event. Events relating to the same
+ * contact point can be identified by the ID of the sequence: contact ID.
+ * Contact ID may be reused after XENKBD_MT_EV_UP event and
+ * is in the [0; XENKBD_FIELD_NUM_CONTACTS - 1] range.
+ *
+ * For further information please refer to documentation on Wayland [1],
+ * Linux [2] and Windows [3] multi-touch support.
+ *
+ * [1] https://cgit.freedesktop.org/wayland/wayland/tree/protocol/wayland.xml
+ * [2] https://www.kernel.org/doc/Documentation/input/multi-touch-protocol.txt
+ * [3] https://msdn.microsoft.com/en-us/library/jj151564(v=vs.85).aspx
+ *
+ *
+ * Multi-touch down event - sent when a new touch is made: touch is assigned
+ * a unique contact ID, sent with this and consequent events related
+ * to this touch.
+ *          0                 1                  2                3        
octet
+ * +-----------------+-----------------+-----------------+-----------------+
+ * |  _TYPE_MTOUCH   |   _MT_EV_DOWN   |    contact_id   |     reserved    |
+ * +-----------------+-----------------+-----------------+-----------------+
+ * |                               reserved                                |
+ * +-----------------+-----------------+-----------------+-----------------+
+ * |                                 abs_x                                 |
+ * +-----------------+-----------------+-----------------+-----------------+
+ * |                                 abs_y                                 |
+ * +-----------------+-----------------+-----------------+-----------------+
+ * |                               reserved                                |
+ * +-----------------+-----------------+-----------------+-----------------+
+ * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
+ * +-----------------+-----------------+-----------------+-----------------+

Please write the byte count to specify how many bytes have been skipped.


As I already commented in [PATCH 1/2] I would keep it as as.
1. "All event packets have the same length (40 octets)"
2.
union xenkbd_in_event
{
    uint8_t type;
...
    char pad[XENKBD_IN_EVENT_SIZE];
};

+ * |                               reserved                                |
+ * +-----------------+-----------------+-----------------+-----------------+
+ *
+ * abs_x - int32_t, absolute X position, in pixels
+ * abs_y - int32_t, absolute Y position, in pixels
+ *
+ * Multi-touch contact release event
+ *          0                 1                  2                3        
octet
+ * +-----------------+-----------------+-----------------+-----------------+
+ * |  _TYPE_MTOUCH   |   _MT_EV_UP     |    contact_id   |     reserved    |
+ * +-----------------+-----------------+-----------------+-----------------+
+ * |                               reserved                                |
+ * +-----------------+-----------------+-----------------+-----------------+
+ * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
+ * +-----------------+-----------------+-----------------+-----------------+

Please write the byte count to specify how many bytes have been skipped.



+ * |                               reserved                                |
+ * +-----------------+-----------------+-----------------+-----------------+
+ *
+ * Multi-touch motion event
+ *          0                 1                  2                3        
octet
+ * +-----------------+-----------------+-----------------+-----------------+
+ * |  _TYPE_MTOUCH   |  _MT_EV_MOTION  |    contact_id   |     reserved    |
+ * +-----------------+-----------------+-----------------+-----------------+
+ * |                               reserved                                |
+ * +-----------------+-----------------+-----------------+-----------------+
+ * |                                 abs_x                                 |
+ * +-----------------+-----------------+-----------------+-----------------+
+ * |                                 abs_y                                 |
+ * +-----------------+-----------------+-----------------+-----------------+
+ * |                               reserved                                |
+ * +-----------------+-----------------+-----------------+-----------------+
+ * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
+ * +-----------------+-----------------+-----------------+-----------------+

Please write the byte count to specify how many bytes have been skipped.



+ * |                               reserved                                |
+ * +-----------------+-----------------+-----------------+-----------------+
+ *
+ * abs_x - int32_t, absolute X position, in pixels,
+ * abs_y - int32_t, absolute Y position, in pixels,
+ *
+ * Multi-touch input synchronization event - shows end of a set of events
+ * which logically belong together.
+ *          0                 1                  2                3        
octet
+ * +-----------------+-----------------+-----------------+-----------------+
+ * |  _TYPE_MTOUCH   |   _MT_EV_SYN    |    contact_id   |     reserved    |
+ * +-----------------+-----------------+-----------------+-----------------+
+ * |                               reserved                                |
+ * +-----------------+-----------------+-----------------+-----------------+
+ * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
+ * +-----------------+-----------------+-----------------+-----------------+

Please write the byte count to specify how many bytes have been skipped.



+ * |                               reserved                                |
+ * +-----------------+-----------------+-----------------+-----------------+
+ *
+ * Multi-touch shape event - touch point's shape has changed its shape.
+ * Shape is approximated by an ellipse through the major and minor axis
+ * lengths: major is the longer diameter of the ellipse and minor is the
+ * shorter one. Center of the ellipse is reported via
+ * XENKBD_MT_EV_DOWN/XENKBD_MT_EV_MOTION events.
+ *          0                 1                  2                3        
octet
+ * +-----------------+-----------------+-----------------+-----------------+
+ * |  _TYPE_MTOUCH   |  _MT_EV_SHAPE   |    contact_id   |     reserved    |
+ * +-----------------+-----------------+-----------------+-----------------+
+ * |                               reserved                                |
+ * +-----------------+-----------------+-----------------+-----------------+
+ * |                                 major                                 |
+ * +-----------------+-----------------+-----------------+-----------------+
+ * |                                 minor                                 |
+ * +-----------------+-----------------+-----------------+-----------------+
+ * |                               reserved                                |
+ * +-----------------+-----------------+-----------------+-----------------+
+ * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
+ * +-----------------+-----------------+-----------------+-----------------+

Please write the byte count to specify how many bytes have been skipped.



+ * |                               reserved                                |
+ * +-----------------+-----------------+-----------------+-----------------+
+ *
+ * major - unt32_t, length of the major axis, pixels
+ * minor - unt32_t, length of the minor axis, pixels
+ *
+ * Multi-touch orientation event - touch point's shape has changed
+ * its orientation: calculated as a clockwise angle between the major axis
+ * of the ellipse and positive Y axis in degrees, [-180; +180].
+ *          0                 1                  2                3        
octet
+ * +-----------------+-----------------+-----------------+-----------------+
+ * |  _TYPE_MTOUCH   |  _MT_EV_ORIENT  |    contact_id   |     reserved    |
+ * +-----------------+-----------------+-----------------+-----------------+
+ * |                               reserved                                |
+ * +-----------------+-----------------+-----------------+-----------------+
+ * |            orientation            |             reserved              |
+ * +-----------------+-----------------+-----------------+-----------------+
+ * |                               reserved                                |
+ * +-----------------+-----------------+-----------------+-----------------+
+ * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
+ * +-----------------+-----------------+-----------------+-----------------+

Please write the byte count to specify how many bytes have been skipped.



+ * |                               reserved                                |
+ * +-----------------+-----------------+-----------------+-----------------+
+ *
+ * orientation - int16_t, clockwise angle of the major axis
+ */
+
+struct xenkbd_mtouch {
+    uint8_t type;             /* XENKBD_TYPE_MTOUCH */
+    uint8_t event_type;       /* XENKBD_MT_EV_??? */
+    uint8_t contact_id;
+    uint8_t reserved[5];      /* reserved for the future use */
+    union {
+        struct {
+            int32_t abs_x;    /* absolute X position, pixels */
+            int32_t abs_y;    /* absolute Y position, pixels */
+        } pos;
+        struct {
+            uint32_t major;   /* length of the major axis, pixels */
+            uint32_t minor;   /* length of the minor axis, pixels */
+        } shape;
+        int16_t orientation;  /* clockwise angle of the major axis */
+    } u;
+};
+
  #define XENKBD_IN_EVENT_SIZE 40
union xenkbd_in_event 
--
2.7.4




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