maru-tablet: improve use of virtio queue

Reduce the buffer size & the scatterlist size.
The size of tablet event is not large.
In addition, the number of generated event is not much.
So only use actually written value.
And fix the incorrect use of the virtio queue.

Change-Id: I9cf1f2cad8cd9f9b6e0ef7783beec48df4c48748
Signed-off-by: Jinhyung Jo <jinhyung.jo@samsung.com>

diff --git a/drivers/maru/maru_virtio_tablet.c b/drivers/maru/maru_virtio_tablet.c
index db23b3fa8c59bd76b557ec934feea8ebfbb96d9a..225db2408998dd9de0c1c4075e2387148ad286da 100644 (file)
--- a/drivers/maru/maru_virtio_tablet.c
+++ b/drivers/maru/maru_virtio_tablet.c
@@ -4,6 +4,8 @@
  * Copyright (c) 2015 Samsung Electronics Co., Ltd. All rights reserved.
  *
  * Contact:
+ *  Jinhyung Jo <jinhyung.jo@samsung.com>
+ *  SeokYeon Hwang <syeon.hwang@samsung.com>
  *  Sungmin Ha <sungmin82.ha@samsung.com>
  *  Sangho Park <sangho.p@samsung.com>
  *
@@ -43,8 +45,7 @@ MODULE_AUTHOR("Sungmin Ha <sungmin82.ha@samsung.com>");
 MODULE_DESCRIPTION("Emulator Virtio Tablet driver");
 
 #define DEVICE_NAME "virtio-tablet"
-#define MAX_BUF_COUNT 256
-static int vqidx = 0;
+#define MAX_BUF_COUNT 25
 
 /* This structure must match the qemu definitions */
 typedef struct EmulTabletEvent {
@@ -55,13 +56,15 @@ typedef struct EmulTabletEvent {
        uint32_t btn_status;
 } EmulTabletEvent;
 
+#define MAX_EVENT_BUF_SIZE (MAX_BUF_COUNT * sizeof(EmulTabletEvent))
+
 typedef struct virtio_tablet
 {
        struct virtio_device *vdev;
        struct virtqueue *vq;
        struct input_dev *idev;
 
-       struct scatterlist sg[MAX_BUF_COUNT];
+       struct scatterlist sg[1];
        struct EmulTabletEvent vbuf[MAX_BUF_COUNT];
 
        struct mutex event_mutex;
@@ -98,59 +101,55 @@ static unsigned int index = 0;
 */
 static void vq_tablet_callback(struct virtqueue *vq)
 {
-       struct EmulTabletEvent tablet_event;
+       struct EmulTabletEvent *token = NULL;
        unsigned int len = 0;
-       void *token = NULL;
+       size_t i, num_event;
 
-       while (1) {
-               memcpy(&tablet_event, &vtb->vbuf[vqidx],
-                       sizeof(tablet_event));
-               if (tablet_event.event_type == 0) {
-                       break;
-               }
+       token = (struct EmulTabletEvent *)virtqueue_get_buf(vq, &len);
+       if (!token) {
+               printk(KERN_ERR "there is no available buffer\n");
+               return;
+       }
 
-               if (tablet_event.event_type == INPUT_BTN) {
+       num_event = (size_t)len / sizeof(struct EmulTabletEvent);
+
+       for (i = 0; i < num_event; i++) {
+               struct EmulTabletEvent event;
+
+               memcpy(&event, &token[i], sizeof(event));
+               if (event.event_type == 0)
+                       continue;
+
+               if (event.event_type == INPUT_BTN) {
                        /* TODO: Implementation for
                         * the remaining events are required. */
-                       if (tablet_event.btn == INPUT_BUTTON_LEFT) {
+                       if (event.btn == INPUT_BUTTON_LEFT) {
                                /* 0x90001 is scan code.
                                 * (logitech left click) */
                                input_event(vtb->idev, EV_MSC, MSC_SCAN,
                                                        0x90001);
                                input_event(vtb->idev, EV_KEY, BTN_LEFT,
-                                               tablet_event.btn_status);
+                                               event.btn_status);
                                input_sync(vtb->idev);
                        }
-               } else if (tablet_event.event_type == INPUT_MOVE) {
+               } else if (event.event_type == INPUT_MOVE) {
                        input_event(vtb->idev, EV_ABS, ABS_X,
-                                               tablet_event.x);
+                                               event.x);
                        input_event(vtb->idev, EV_ABS, ABS_Y,
-                                               tablet_event.y);
+                                               event.y);
                        input_sync(vtb->idev);
                } else {
                        printk(KERN_ERR "Unknown event type\n");
                        break;
                }
+       }
+       memset(vtb->vbuf, 0x00, MAX_EVENT_BUF_SIZE);
 
-               memset(&vtb->vbuf[vqidx], 0x00,
-                               sizeof(tablet_event));
-               token = virtqueue_get_buf(vtb->vq, &len);
-               if (!token) {
-                       printk(KERN_ERR "failed to virtqueue_get_buf\n");
-                       return;
-               }
-
-               err = virtqueue_add_inbuf(vtb->vq, vtb->sg,
-                               MAX_BUF_COUNT, token, GFP_ATOMIC);
-               if (err < 0) {
-                       printk(KERN_ERR "failed to add buffer to virtqueue\n");
-                       return;
-               }
-
-               vqidx++;
-               if (vqidx == MAX_BUF_COUNT) {
-                       vqidx = 0;
-               }
+       err = virtqueue_add_inbuf(vtb->vq, vtb->sg, 1,
+                               (void *)vtb->vbuf, GFP_ATOMIC);
+       if (err < 0) {
+               printk(KERN_ERR "failed to add buffer to virtqueue\n");
+               return;
        }
 
        virtqueue_kick(vtb->vq);
@@ -159,7 +158,6 @@ static void vq_tablet_callback(struct virtqueue *vq)
 static int virtio_tablet_probe(struct virtio_device *vdev)
 {
        int ret = 0;
-       vqidx = 0;
 
        printk(KERN_INFO "virtio tablet driver is probed\n");
 
@@ -183,24 +181,11 @@ static int virtio_tablet_probe(struct virtio_device *vdev)
        /* enable callback */
        virtqueue_enable_cb(vtb->vq);
 
-       sg_init_table(vtb->sg, MAX_BUF_COUNT);
-
        /* prepare the buffers */
-       for (index = 0; index < MAX_BUF_COUNT; index++) {
-               sg_set_buf(&vtb->sg[index], &vtb->vbuf[index],
-                               sizeof(EmulTabletEvent));
-
-               if (err < 0) {
-                       printk(KERN_ERR "failed to add buffer\n");
-                       kfree(vtb);
-                       vdev->priv = NULL;
-                       return ret;
-               }
-       }
+       sg_init_one(vtb->sg, vtb->vbuf, MAX_EVENT_BUF_SIZE);
 
-       err = virtqueue_add_inbuf(vtb->vq, vtb->sg,
-                       MAX_BUF_COUNT, (void *)MAX_BUF_COUNT,
-                       GFP_ATOMIC);
+       err = virtqueue_add_inbuf(vtb->vq, vtb->sg, 1,
+                       (void *)vtb->vbuf, GFP_ATOMIC);
 
        /* register for input device */
        vtb->idev = input_allocate_device();