[PATCH] virtio-input: add multi-touch support

[Vasyl Vavrychuk <vasyl.vavrychuk@opensynergy.com>]

From: Mathias Crombez <mathias.crombez@faurecia.com>

Without multi-touch slots allocated, ABS_MT_SLOT events will be lost by
input_handle_abs_event.

Signed-off-by: Mathias Crombez <mathias.crombez@faurecia.com>
Signed-off-by: Vasyl Vavrychuk <vasyl.vavrychuk@opensynergy.com>
Tested-by: Vasyl Vavrychuk <vasyl.vavrychuk@opensynergy.com>
---
 drivers/virtio/Kconfig        | 11 +++++++++++
 drivers/virtio/virtio_input.c |  8 ++++++++
 2 files changed, 19 insertions(+)

diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig
index 7b41130d3f35..2cfd5b01d96d 100644
--- a/drivers/virtio/Kconfig
+++ b/drivers/virtio/Kconfig
@@ -111,6 +111,17 @@ config VIRTIO_INPUT

         If unsure, say M.

+config VIRTIO_INPUT_MULTITOUCH_SLOTS
+       depends on VIRTIO_INPUT
+       int "Number of multitouch slots"
+       range 0 64
+       default 10
+       help
+        Define the number of multitouch slots used. Default to 10.
+        This parameter is unused if there is no multitouch capability.
+
+        0 will disable the feature.
+
 config VIRTIO_MMIO
        tristate "Platform bus driver for memory mapped virtio devices"
        depends on HAS_IOMEM && HAS_DMA
diff --git a/drivers/virtio/virtio_input.c b/drivers/virtio/virtio_input.c
index f1f6208edcf5..13f3d90e6c30 100644
--- a/drivers/virtio/virtio_input.c
+++ b/drivers/virtio/virtio_input.c
@@ -7,6 +7,7 @@

 #include <uapi/linux/virtio_ids.h>
 #include <uapi/linux/virtio_input.h>
+#include <linux/input/mt.h>

 struct virtio_input {
        struct virtio_device       *vdev;
@@ -205,6 +206,7 @@ static int virtinput_probe(struct virtio_device *vdev)
        unsigned long flags;
        size_t size;
        int abs, err;
+       bool is_mt = false;

        if (!virtio_has_feature(vdev, VIRTIO_F_VERSION_1))
                return -ENODEV;
@@ -287,9 +289,15 @@ static int virtinput_probe(struct virtio_device *vdev)
                for (abs = 0; abs < ABS_CNT; abs++) {
                        if (!test_bit(abs, vi->idev->absbit))
                                continue;
+                       if (input_is_mt_value(abs))
+                               is_mt = true;
                        virtinput_cfg_abs(vi, abs);
                }
        }
+       if (is_mt)
+               input_mt_init_slots(vi->idev,
+                                   CONFIG_VIRTIO_INPUT_MULTITOUCH_SLOTS,
+                                   INPUT_MT_DIRECT);

        virtio_device_ready(vdev);
        vi->ready = true;
--
2.23.0


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