[media] gspca: Update / fix various comments wrt workqueue usb_lock usage

[~andy/linux] / drivers / media / usb / gspca / finepix.c

diff --git a/drivers/media/usb/gspca/finepix.c b/drivers/media/usb/gspca/finepix.c
index c8f2201cc35ad96403230150b999363a7f362a93..52bdb569760b4139bb20dfca693746b5a267ddf6 100644 (file)
--- a/drivers/media/usb/gspca/finepix.c
+++ b/drivers/media/usb/gspca/finepix.c
@@ -77,7 +77,14 @@ static int command(struct gspca_dev *gspca_dev,
                        12, FPIX_TIMEOUT);
 }
 
-/* workqueue */
+/*
+ * This function is called as a workqueue function and runs whenever the camera
+ * is streaming data. Because it is a workqueue function it is allowed to sleep
+ * so we can use synchronous USB calls. To avoid possible collisions with other
+ * threads attempting to use gspca_dev->usb_buf we take the usb_lock when
+ * performing USB operations using it. In practice we don't really need this
+ * as the camera doesn't provide any controls.
+ */
 static void dostream(struct work_struct *work)
 {
        struct usb_fpix *dev = container_of(work, struct usb_fpix, work_struct);
@@ -87,14 +94,11 @@ static void dostream(struct work_struct *work)
        int ret = 0;
        int len;
 
-       /* synchronize with the main driver */
-       mutex_lock(&gspca_dev->usb_lock);
-       mutex_unlock(&gspca_dev->usb_lock);
        PDEBUG(D_STREAM, "dostream started");
 
        /* loop reading a frame */
 again:
-       while (gspca_dev->dev && gspca_dev->streaming) {
+       while (gspca_dev->present && gspca_dev->streaming) {
 #ifdef CONFIG_PM
                if (gspca_dev->frozen)
                        break;
@@ -110,7 +114,7 @@ again:
                if (gspca_dev->frozen)
                        break;
 #endif
-               if (!gspca_dev->dev || !gspca_dev->streaming)
+               if (!gspca_dev->present || !gspca_dev->streaming)
                        break;
 
                /* the frame comes in parts */
@@ -129,7 +133,7 @@ again:
                        if (gspca_dev->frozen)
                                goto out;
 #endif
-                       if (!gspca_dev->dev || !gspca_dev->streaming)
+                       if (!gspca_dev->present || !gspca_dev->streaming)
                                goto out;
                        if (len < FPIX_MAX_TRANSFER ||
                                (data[len - 2] == 0xff &&