1 files changed, 26 insertions, 30 deletions

diff --git a/drivers/media/video/gspca/sq905.c b/drivers/media/video/gspca/sq905.c
index 715a68f0156e..547d1fd5191d 100644
--- a/drivers/media/video/gspca/sq905.c
+++ b/drivers/media/video/gspca/sq905.c
@@ -168,18 +168,22 @@ static int sq905_ack_frame(struct gspca_dev *gspca_dev)
  *  request and read a block of data - see warning on sq905_command.
  */
 static int
-sq905_read_data(struct gspca_dev *gspca_dev, u8 *data, int size)
+sq905_read_data(struct gspca_dev *gspca_dev, u8 *data, int size, int need_lock)
 {
         int ret;
         int act_len;
 
         gspca_dev->usb_buf[0] = '\0';
+        if (need_lock)
+                mutex_lock(&gspca_dev->usb_lock);
         ret = usb_control_msg(gspca_dev->dev,
                               usb_sndctrlpipe(gspca_dev->dev, 0),
                               USB_REQ_SYNCH_FRAME,                /* request */
                               USB_DIR_OUT | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
                               SQ905_BULK_READ, size, gspca_dev->usb_buf,
                               1, SQ905_CMD_TIMEOUT);
+        if (need_lock)
+                mutex_unlock(&gspca_dev->usb_lock);
         if (ret < 0) {
                 PDEBUG(D_ERR, "%s: usb_control_msg failed (%d)", __func__, ret);
                 return ret;
@@ -214,7 +218,6 @@ static void sq905_dostream(struct work_struct *work)
         int bytes_left; /* bytes remaining in current frame. */
         int data_len;   /* size to use for the next read. */
         int header_read; /* true if we have already read the frame header. */
-        int discarding; /* true if we failed to get space for frame. */
         int packet_type;
         int frame_sz;
         int ret;
@@ -222,7 +225,6 @@ static void sq905_dostream(struct work_struct *work)
         u8 *buffer;
 
         buffer = kmalloc(SQ905_MAX_TRANSFER, GFP_KERNEL | GFP_DMA);
-        mutex_lock(&gspca_dev->usb_lock);
         if (!buffer) {
                 PDEBUG(D_ERR, "Couldn't allocate USB buffer");
                 goto quit_stream;
@@ -232,28 +234,22 @@ static void sq905_dostream(struct work_struct *work)
                         + FRAME_HEADER_LEN;
 
         while (gspca_dev->present && gspca_dev->streaming) {
-                /* Need a short delay to ensure streaming flag was set by
-                 * gspca and to make sure gspca can grab the mutex. */
-                mutex_unlock(&gspca_dev->usb_lock);
-                msleep(1);
-
                 /* request some data and then read it until we have
                  * a complete frame. */
                 bytes_left = frame_sz;
                 header_read = 0;
-                discarding = 0;
 
-                while (bytes_left > 0) {
+                /* Note we do not check for gspca_dev->streaming here, as
+                   we must finish reading an entire frame, otherwise the
+                   next time we stream we start reading in the middle of a
+                   frame. */
+                while (bytes_left > 0 && gspca_dev->present) {
                         data_len = bytes_left > SQ905_MAX_TRANSFER ?
                                 SQ905_MAX_TRANSFER : bytes_left;
-                        mutex_lock(&gspca_dev->usb_lock);
-                        if (!gspca_dev->present)
-                                goto quit_stream;
-                        ret = sq905_read_data(gspca_dev, buffer, data_len);
+                        ret = sq905_read_data(gspca_dev, buffer, data_len, 1);
                         if (ret < 0)
                                 goto quit_stream;
-                        mutex_unlock(&gspca_dev->usb_lock);
-                        PDEBUG(D_STREAM,
+                        PDEBUG(D_PACK,
                                 "Got %d bytes out of %d for frame",
                                 data_len, bytes_left);
                         bytes_left -= data_len;
@@ -271,7 +267,7 @@ static void sq905_dostream(struct work_struct *work)
                                 packet_type = INTER_PACKET;
                         }
                         frame = gspca_get_i_frame(gspca_dev);
-                        if (frame && !discarding) {
+                        if (frame) {
                                 frame = gspca_frame_add(gspca_dev, packet_type,
                                                 frame, data, data_len);
                                 /* If entire frame fits in one packet we still
@@ -281,23 +277,23 @@ static void sq905_dostream(struct work_struct *work)
                                         frame = gspca_frame_add(gspca_dev,
                                                         LAST_PACKET,
                                                         frame, data, 0);
-                        } else {
-                                discarding = 1;
                         }
                 }
-                /* acknowledge the frame */
-                mutex_lock(&gspca_dev->usb_lock);
-                if (!gspca_dev->present)
-                        goto quit_stream;
-                ret = sq905_ack_frame(gspca_dev);
-                if (ret < 0)
-                        goto quit_stream;
+                if (gspca_dev->present) {
+                        /* acknowledge the frame */
+                        mutex_lock(&gspca_dev->usb_lock);
+                        ret = sq905_ack_frame(gspca_dev);
+                        mutex_unlock(&gspca_dev->usb_lock);
+                        if (ret < 0)
+                                goto quit_stream;
+                }
         }
 quit_stream:
-        /* the usb_lock is already acquired */
-        if (gspca_dev->present)
+        if (gspca_dev->present) {
+                mutex_lock(&gspca_dev->usb_lock);
                 sq905_command(gspca_dev, SQ905_CLEAR);
-        mutex_unlock(&gspca_dev->usb_lock);
+                mutex_unlock(&gspca_dev->usb_lock);
+        }
         kfree(buffer);
 }
 
@@ -346,7 +342,7 @@ static int sd_init(struct gspca_dev *gspca_dev)
         ret = sq905_command(gspca_dev, SQ905_ID);
         if (ret < 0)
                 return ret;
-        ret = sq905_read_data(gspca_dev, gspca_dev->usb_buf, 4);
+        ret = sq905_read_data(gspca_dev, gspca_dev->usb_buf, 4, 0);
         if (ret < 0)
                 return ret;
         /* usb_buf is allocated with kmalloc so is aligned.