From: Hans Verkuil <hans.verkuil@xxxxxxxxx>
Due to latency concerns the VIDIOC_QBUF, DQBUF and QUERYBUF do not use the
core lock, instead they rely only on queue_lock.
Signed-off-by: Hans Verkuil <hans.verkuil@xxxxxxxxx>
---
drivers/media/video/gspca/gspca.c | 203 ++++++++-----------------------------
1 file changed, 41 insertions(+), 162 deletions(-)
diff --git a/drivers/media/video/gspca/gspca.c b/drivers/media/video/gspca/gspca.c
index f840bed..edca4f3 100644
--- a/drivers/media/video/gspca/gspca.c
+++ b/drivers/media/video/gspca/gspca.c
@@ -850,14 +850,6 @@ static int gspca_init_transfer(struct gspca_dev *gspca_dev)
struct ep_tb_s ep_tb[MAX_ALT];
int n, ret, xfer, alt, alt_idx;
- if (mutex_lock_interruptible(&gspca_dev->usb_lock))
- return -ERESTARTSYS;
-
- if (!gspca_dev->present) {
- ret = -ENODEV;
- goto unlock;
- }
-
/* reset the streaming variables */
gspca_dev->image = NULL;
gspca_dev->image_len = 0;
@@ -872,7 +864,7 @@ static int gspca_init_transfer(struct gspca_dev *gspca_dev)
if (gspca_dev->sd_desc->isoc_init) {
ret = gspca_dev->sd_desc->isoc_init(gspca_dev);
if (ret < 0)
- goto unlock;
+ return ret;
}
xfer = gspca_dev->cam.bulk ? USB_ENDPOINT_XFER_BULK
: USB_ENDPOINT_XFER_ISOC;
@@ -883,8 +875,7 @@ static int gspca_init_transfer(struct gspca_dev *gspca_dev)
ep = alt_xfer(&intf->altsetting[gspca_dev->alt], xfer);
if (ep == NULL) {
pr_err("bad altsetting %d\n", gspca_dev->alt);
- ret = -EIO;
- goto out;
+ return -EIO;
}
ep_tb[0].alt = gspca_dev->alt;
alt_idx = 1;
@@ -895,8 +886,7 @@ static int gspca_init_transfer(struct gspca_dev *gspca_dev)
alt_idx = build_isoc_ep_tb(gspca_dev, intf, ep_tb);
if (alt_idx <= 0) {
pr_err("no transfer endpoint found\n");
- ret = -EIO;
- goto unlock;
+ return -EIO;
}
}
@@ -991,8 +981,6 @@ retry:
}
out:
gspca_input_create_urb(gspca_dev);
-unlock:
- mutex_unlock(&gspca_dev->usb_lock);
return ret;
}
@@ -1062,7 +1050,6 @@ static int gspca_get_mode(struct gspca_dev *gspca_dev,
static int vidioc_g_register(struct file *file, void *priv,
struct v4l2_dbg_register *reg)
{
- int ret;
struct gspca_dev *gspca_dev = video_drvdata(file);
if (!gspca_dev->sd_desc->get_chip_ident)
@@ -1071,22 +1058,13 @@ static int vidioc_g_register(struct file *file, void *priv,
if (!gspca_dev->sd_desc->get_register)
return -ENOTTY;
- if (mutex_lock_interruptible(&gspca_dev->usb_lock))
- return -ERESTARTSYS;
gspca_dev->usb_err = 0;
- if (gspca_dev->present)
- ret = gspca_dev->sd_desc->get_register(gspca_dev, reg);
- else
- ret = -ENODEV;
- mutex_unlock(&gspca_dev->usb_lock);
-
- return ret;
+ return gspca_dev->sd_desc->get_register(gspca_dev, reg);
}
static int vidioc_s_register(struct file *file, void *priv,
struct v4l2_dbg_register *reg)
{
- int ret;
struct gspca_dev *gspca_dev = video_drvdata(file);
if (!gspca_dev->sd_desc->get_chip_ident)
@@ -1095,38 +1073,21 @@ static int vidioc_s_register(struct file *file, void *priv,
if (!gspca_dev->sd_desc->set_register)
return -ENOTTY;
- if (mutex_lock_interruptible(&gspca_dev->usb_lock))
- return -ERESTARTSYS;
gspca_dev->usb_err = 0;
- if (gspca_dev->present)
- ret = gspca_dev->sd_desc->set_register(gspca_dev, reg);
- else
- ret = -ENODEV;
- mutex_unlock(&gspca_dev->usb_lock);
-
- return ret;
+ return gspca_dev->sd_desc->set_register(gspca_dev, reg);
}
#endif
static int vidioc_g_chip_ident(struct file *file, void *priv,
struct v4l2_dbg_chip_ident *chip)
{
- int ret;
struct gspca_dev *gspca_dev = video_drvdata(file);
if (!gspca_dev->sd_desc->get_chip_ident)
return -ENOTTY;
- if (mutex_lock_interruptible(&gspca_dev->usb_lock))
- return -ERESTARTSYS;
gspca_dev->usb_err = 0;
- if (gspca_dev->present)
- ret = gspca_dev->sd_desc->get_chip_ident(gspca_dev, chip);
- else
- ret = -ENODEV;
- mutex_unlock(&gspca_dev->usb_lock);
-
- return ret;
+ return gspca_dev->sd_desc->get_chip_ident(gspca_dev, chip);
}
static int vidioc_enum_fmt_vid_cap(struct file *file, void *priv,
@@ -1339,8 +1300,6 @@ static int dev_open(struct file *file)
struct gspca_dev *gspca_dev = video_drvdata(file);
PDEBUG(D_STREAM, "[%s] open", current->comm);
- if (!gspca_dev->present)
- return -ENODEV;
/* protect the subdriver against rmmod */
if (!try_module_get(gspca_dev->module))
@@ -1369,10 +1328,8 @@ static int dev_close(struct file *file)
/* if the file did the capture, free the streaming resources */
if (gspca_dev->capt_file == file) {
if (gspca_dev->streaming) {
- mutex_lock(&gspca_dev->usb_lock);
gspca_dev->usb_err = 0;
gspca_stream_off(gspca_dev);
- mutex_unlock(&gspca_dev->usb_lock);
}
frame_free(gspca_dev);
}
@@ -1388,15 +1345,7 @@ static int vidioc_querycap(struct file *file, void *priv,
struct v4l2_capability *cap)
{
struct gspca_dev *gspca_dev = video_drvdata(file);
- int ret;
- /* protect the access to the usb device */
- if (mutex_lock_interruptible(&gspca_dev->usb_lock))
- return -ERESTARTSYS;
- if (!gspca_dev->present) {
- ret = -ENODEV;
- goto out;
- }
strlcpy((char *) cap->driver, gspca_dev->sd_desc->name,
sizeof cap->driver);
if (gspca_dev->dev->product != NULL) {
@@ -1414,10 +1363,7 @@ static int vidioc_querycap(struct file *file, void *priv,
| V4L2_CAP_STREAMING
| V4L2_CAP_READWRITE;
cap->capabilities = cap->device_caps | V4L2_CAP_DEVICE_CAPS;
- ret = 0;
-out:
- mutex_unlock(&gspca_dev->usb_lock);
- return ret;
+ return 0;
}
static int get_ctrl(struct gspca_dev *gspca_dev,
@@ -1486,7 +1432,7 @@ static int vidioc_s_ctrl(struct file *file, void *priv,
struct gspca_dev *gspca_dev = video_drvdata(file);
const struct ctrl *ctrls;
struct gspca_ctrl *gspca_ctrl;
- int idx, ret;
+ int idx;
idx = get_ctrl(gspca_dev, ctrl->id);
if (idx < 0)
@@ -1506,27 +1452,16 @@ static int vidioc_s_ctrl(struct file *file, void *priv,
return -ERANGE;
}
PDEBUG(D_CONF, "set ctrl [%08x] = %d", ctrl->id, ctrl->value);
- if (mutex_lock_interruptible(&gspca_dev->usb_lock))
- return -ERESTARTSYS;
- if (!gspca_dev->present) {
- ret = -ENODEV;
- goto out;
- }
gspca_dev->usb_err = 0;
- if (ctrls->set != NULL) {
- ret = ctrls->set(gspca_dev, ctrl->value);
- goto out;
- }
+ if (ctrls->set != NULL)
+ return ctrls->set(gspca_dev, ctrl->value);
if (gspca_ctrl != NULL) {
gspca_ctrl->val = ctrl->value;
if (ctrls->set_control != NULL
&& gspca_dev->streaming)
ctrls->set_control(gspca_dev);
}
- ret = gspca_dev->usb_err;
-out:
- mutex_unlock(&gspca_dev->usb_lock);
- return ret;
+ return gspca_dev->usb_err;
}
static int vidioc_g_ctrl(struct file *file, void *priv,
@@ -1534,30 +1469,19 @@ static int vidioc_g_ctrl(struct file *file, void *priv,
{
struct gspca_dev *gspca_dev = video_drvdata(file);
const struct ctrl *ctrls;
- int idx, ret;
+ int idx;
idx = get_ctrl(gspca_dev, ctrl->id);
if (idx < 0)
return -EINVAL;
ctrls = &gspca_dev->sd_desc->ctrls[idx];
- if (mutex_lock_interruptible(&gspca_dev->usb_lock))
- return -ERESTARTSYS;
- if (!gspca_dev->present) {
- ret = -ENODEV;
- goto out;
- }
gspca_dev->usb_err = 0;
- if (ctrls->get != NULL) {
- ret = ctrls->get(gspca_dev, &ctrl->value);
- goto out;
- }
+ if (ctrls->get != NULL)
+ return ctrls->get(gspca_dev, &ctrl->value);
if (gspca_dev->cam.ctrls != NULL)
ctrl->value = gspca_dev->cam.ctrls[idx].val;
- ret = 0;
-out:
- mutex_unlock(&gspca_dev->usb_lock);
- return ret;
+ return 0;
}
static int vidioc_querymenu(struct file *file, void *priv,
@@ -1640,10 +1564,8 @@ static int vidioc_reqbufs(struct file *file, void *priv,
/* stop streaming */
streaming = gspca_dev->streaming;
if (streaming) {
- mutex_lock(&gspca_dev->usb_lock);
gspca_dev->usb_err = 0;
gspca_stream_off(gspca_dev);
- mutex_unlock(&gspca_dev->usb_lock);
/* Don't restart the stream when switching from read
* to mmap mode */
@@ -1736,10 +1658,8 @@ static int vidioc_streamoff(struct file *file, void *priv,
if (mutex_lock_interruptible(&gspca_dev->queue_lock))
return -ERESTARTSYS;
- if (!gspca_dev->streaming) {
- ret = 0;
- goto out;
- }
+ if (!gspca_dev->streaming)
+ return 0;
/* check the capture file */
if (gspca_dev->capt_file != file) {
@@ -1748,13 +1668,8 @@ static int vidioc_streamoff(struct file *file, void *priv,
}
/* stop streaming */
- if (mutex_lock_interruptible(&gspca_dev->usb_lock)) {
- ret = -ERESTARTSYS;
- goto out;
- }
gspca_dev->usb_err = 0;
gspca_stream_off(gspca_dev);
- mutex_unlock(&gspca_dev->usb_lock);
/* In case another thread is waiting in dqbuf */
wake_up_interruptible(&gspca_dev->wq);
@@ -1772,63 +1687,36 @@ static int vidioc_g_jpegcomp(struct file *file, void *priv,
struct v4l2_jpegcompression *jpegcomp)
{
struct gspca_dev *gspca_dev = video_drvdata(file);
- int ret;
if (!gspca_dev->sd_desc->get_jcomp)
return -ENOTTY;
- if (mutex_lock_interruptible(&gspca_dev->usb_lock))
- return -ERESTARTSYS;
gspca_dev->usb_err = 0;
- if (gspca_dev->present)
- ret = gspca_dev->sd_desc->get_jcomp(gspca_dev, jpegcomp);
- else
- ret = -ENODEV;
- mutex_unlock(&gspca_dev->usb_lock);
- return ret;
+ return gspca_dev->sd_desc->get_jcomp(gspca_dev, jpegcomp);
}
static int vidioc_s_jpegcomp(struct file *file, void *priv,
struct v4l2_jpegcompression *jpegcomp)
{
struct gspca_dev *gspca_dev = video_drvdata(file);
- int ret;
if (!gspca_dev->sd_desc->set_jcomp)
return -ENOTTY;
- if (mutex_lock_interruptible(&gspca_dev->usb_lock))
- return -ERESTARTSYS;
gspca_dev->usb_err = 0;
- if (gspca_dev->present)
- ret = gspca_dev->sd_desc->set_jcomp(gspca_dev, jpegcomp);
- else
- ret = -ENODEV;
- mutex_unlock(&gspca_dev->usb_lock);
- return ret;
+ return gspca_dev->sd_desc->set_jcomp(gspca_dev, jpegcomp);
}
static int vidioc_g_parm(struct file *filp, void *priv,
struct v4l2_streamparm *parm)
{
- struct gspca_dev *gspca_dev = video_drvdata(file);
+ struct gspca_dev *gspca_dev = video_drvdata(filp);
parm->parm.capture.readbuffers = gspca_dev->nbufread;
if (gspca_dev->sd_desc->get_streamparm) {
- int ret;
-
- if (mutex_lock_interruptible(&gspca_dev->usb_lock))
- return -ERESTARTSYS;
- if (gspca_dev->present) {
- gspca_dev->usb_err = 0;
- gspca_dev->sd_desc->get_streamparm(gspca_dev, parm);
- ret = gspca_dev->usb_err;
- } else {
- ret = -ENODEV;
- }
- mutex_unlock(&gspca_dev->usb_lock);
- return ret;
+ gspca_dev->usb_err = 0;
+ gspca_dev->sd_desc->get_streamparm(gspca_dev, parm);
+ return gspca_dev->usb_err;
}
-
return 0;
}
@@ -1845,19 +1733,9 @@ static int vidioc_s_parm(struct file *filp, void *priv,
gspca_dev->nbufread = n;
if (gspca_dev->sd_desc->set_streamparm) {
- int ret;
-
- if (mutex_lock_interruptible(&gspca_dev->usb_lock))
- return -ERESTARTSYS;
- if (gspca_dev->present) {
- gspca_dev->usb_err = 0;
- gspca_dev->sd_desc->set_streamparm(gspca_dev, parm);
- ret = gspca_dev->usb_err;
- } else {
- ret = -ENODEV;
- }
- mutex_unlock(&gspca_dev->usb_lock);
- return ret;
+ gspca_dev->usb_err = 0;
+ gspca_dev->sd_desc->set_streamparm(gspca_dev, parm);
+ return gspca_dev->usb_err;
}
return 0;
@@ -1877,10 +1755,6 @@ static int dev_mmap(struct file *file, struct vm_area_struct *vma)
if (mutex_lock_interruptible(&gspca_dev->queue_lock))
return -ERESTARTSYS;
- if (!gspca_dev->present) {
- ret = -ENODEV;
- goto out;
- }
if (gspca_dev->capt_file != file) {
ret = -EINVAL;
goto out;
@@ -2009,11 +1883,9 @@ static int vidioc_dqbuf(struct file *file, void *priv,
gspca_dev->fr_o = (i + 1) % GSPCA_MAX_FRAMES;
if (gspca_dev->sd_desc->dq_callback) {
- mutex_lock(&gspca_dev->usb_lock);
gspca_dev->usb_err = 0;
if (gspca_dev->present)
gspca_dev->sd_desc->dq_callback(gspca_dev);
- mutex_unlock(&gspca_dev->usb_lock);
}
frame->v4l2_buf.flags &= ~V4L2_BUF_FLAG_DONE;
@@ -2366,6 +2238,7 @@ int gspca_dev_probe2(struct usb_interface *intf,
gspca_dev->present = 1;
mutex_init(&gspca_dev->usb_lock);
+ gspca_dev->vdev.lock = &gspca_dev->usb_lock;
mutex_init(&gspca_dev->queue_lock);
init_waitqueue_head(&gspca_dev->wq);
@@ -2388,6 +2261,14 @@ int gspca_dev_probe2(struct usb_interface *intf,
if (ret)
goto out;
+ /* These ioctls use just queue_lock and not usb_lock.
+ This improves latency if the usb lock is taken for a
+ long time, e.g. when changing a control value, and a
+ new frame is ready to be dequeued. */
+ v4l2_dont_use_lock(&gspca_dev->vdev, VIDIOC_DQBUF);
+ v4l2_dont_use_lock(&gspca_dev->vdev, VIDIOC_QBUF);
+ v4l2_dont_use_lock(&gspca_dev->vdev, VIDIOC_QUERYBUF);
+
/* init video stuff */
ret = video_register_device(&gspca_dev->vdev,
VFL_TYPE_GRABBER,
@@ -2493,17 +2374,16 @@ int gspca_suspend(struct usb_interface *intf, pm_message_t message)
if (!gspca_dev->streaming)
return 0;
+ mutex_lock(&gspca_dev->usb_lock);
gspca_dev->frozen = 1; /* avoid urb error messages */
if (gspca_dev->sd_desc->stopN)
gspca_dev->sd_desc->stopN(gspca_dev);
destroy_urbs(gspca_dev);
gspca_input_destroy_urb(gspca_dev);
gspca_set_alt0(gspca_dev);
- if (gspca_dev->sd_desc->stop0) {
- mutex_lock(&gspca_dev->usb_lock);
+ if (gspca_dev->sd_desc->stop0)
gspca_dev->sd_desc->stop0(gspca_dev);
- mutex_unlock(&gspca_dev->usb_lock);
- }
+ mutex_unlock(&gspca_dev->usb_lock);
return 0;
}
EXPORT_SYMBOL(gspca_suspend);
@@ -2513,15 +2393,14 @@ int gspca_resume(struct usb_interface *intf)
struct gspca_dev *gspca_dev = usb_get_intfdata(intf);
int ret = 0;
+ mutex_lock(&gspca_dev->usb_lock);
gspca_dev->frozen = 0;
gspca_dev->sd_desc->init(gspca_dev);
gspca_set_default_mode(gspca_dev);
gspca_input_create_urb(gspca_dev);
- if (gspca_dev->streaming) {
- mutex_lock(&gspca_dev->queue_lock);
+ if (gspca_dev->streaming)
ret = gspca_init_transfer(gspca_dev);
- mutex_unlock(&gspca_dev->queue_lock);
- }
+ mutex_unlock(&gspca_dev->usb_lock);
return ret;
}
EXPORT_SYMBOL(gspca_resume);
--
1.7.10
--
To unsubscribe from this list: send the line "unsubscribe linux-media" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
