[PATCH v2] media: uvcvideo: Do power management granularly

From: Ricardo Ribalda
Date: Mon Jan 24 2022 - 11:00:24 EST

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Instead of suspending/resume the USB device at open()/close(), do it
when the device is actually used.

This way we can reduce the power consumption when a service is holding
the video device and leaving it in an idle state.

Signed-off-by: Ricardo Ribalda <ribalda@xxxxxxxxxxxx>
---

v2: Kudos to Laurent!

We cannot suspend if we can read events from the video device.

drivers/media/usb/uvc/uvc_v4l2.c | 202 +++++++++++++++++++++++++------
drivers/media/usb/uvc/uvcvideo.h | 1 +
2 files changed, 169 insertions(+), 34 deletions(-)

diff --git a/drivers/media/usb/uvc/uvc_v4l2.c b/drivers/media/usb/uvc/uvc_v4l2.c
index 711556d13d03..f557ba0daa46 100644
--- a/drivers/media/usb/uvc/uvc_v4l2.c
+++ b/drivers/media/usb/uvc/uvc_v4l2.c
@@ -25,6 +25,55 @@

#include "uvcvideo.h"

+/* ------------------------------------------------------------------------
+ * UVC power management
+ */
+
+static int uvc_pm_get(struct uvc_streaming *stream)
+{
+ int ret = 0;
+
+ if (!video_is_registered(&stream->vdev))
+ return -ENODEV;
+
+ /*
+ * We cannot hold dev->lock when calling autopm_get_interface.
+ */
+ ret = usb_autopm_get_interface(stream->dev->intf);
+ if (ret)
+ return ret;
+
+ mutex_lock(&stream->dev->lock);
+ if (!stream->dev->users)
+ ret = uvc_status_start(stream->dev, GFP_KERNEL);
+ if (!ret)
+ stream->dev->users++;
+ mutex_unlock(&stream->dev->lock);
+
+ if (ret)
+ usb_autopm_put_interface(stream->dev->intf);
+
+ return ret;
+}
+
+static void uvc_pm_put(struct uvc_streaming *stream)
+{
+ if (!video_is_registered(&stream->vdev))
+ return;
+
+ mutex_lock(&stream->dev->lock);
+ if (WARN_ON(!stream->dev->users)) {
+ mutex_unlock(&stream->dev->lock);
+ return;
+ }
+ stream->dev->users--;
+ if (!stream->dev->users)
+ uvc_status_stop(stream->dev);
+ mutex_unlock(&stream->dev->lock);
+
+ usb_autopm_put_interface(stream->dev->intf);
+}
+
/* ------------------------------------------------------------------------
* UVC ioctls
*/
@@ -251,8 +300,14 @@ static int uvc_v4l2_try_format(struct uvc_streaming *stream,
stream->ctrl.dwMaxVideoFrameSize;

/* Probe the device. */
+ ret = uvc_pm_get(stream);
+ if (ret) {
+ mutex_unlock(&stream->mutex);
+ goto done;
+ }
ret = uvc_probe_video(stream, probe);
mutex_unlock(&stream->mutex);
+ uvc_pm_put(stream);
if (ret < 0)
goto done;

@@ -464,7 +519,13 @@ static int uvc_v4l2_set_streamparm(struct uvc_streaming *stream,
}

/* Probe the device with the new settings. */
+ ret = uvc_pm_get(stream);
+ if (ret) {
+ mutex_unlock(&stream->mutex);
+ return ret;
+ }
ret = uvc_probe_video(stream, &probe);
+ uvc_pm_put(stream);
if (ret < 0) {
mutex_unlock(&stream->mutex);
return ret;
@@ -555,35 +616,25 @@ static int uvc_v4l2_open(struct file *file)
{
struct uvc_streaming *stream;
struct uvc_fh *handle;
- int ret = 0;

stream = video_drvdata(file);
uvc_dbg(stream->dev, CALLS, "%s\n", __func__);

- ret = usb_autopm_get_interface(stream->dev->intf);
- if (ret < 0)
- return ret;
-
/* Create the device handle. */
handle = kzalloc(sizeof(*handle), GFP_KERNEL);
- if (handle == NULL) {
- usb_autopm_put_interface(stream->dev->intf);
+ if (!handle)
return -ENOMEM;
- }

- mutex_lock(&stream->dev->lock);
- if (stream->dev->users == 0) {
- ret = uvc_status_start(stream->dev, GFP_KERNEL);
- if (ret < 0) {
- mutex_unlock(&stream->dev->lock);
- usb_autopm_put_interface(stream->dev->intf);
- kfree(handle);
- return ret;
- }
+ /*
+ * If the uvc evdev exists we cannot suspend when the device
+ * is idle. Otherwise we will miss button actions.
+ */
+#ifdef CONFIG_USB_VIDEO_CLASS_INPUT_EVDEV
+ if (uvc_pm_get(stream)) {
+ kfree(handle);
+ return -ENODEV;
}
-
- stream->dev->users++;
- mutex_unlock(&stream->dev->lock);
+#endif

v4l2_fh_init(&handle->vfh, &stream->vdev);
v4l2_fh_add(&handle->vfh);
@@ -606,6 +657,13 @@ static int uvc_v4l2_release(struct file *file)
if (uvc_has_privileges(handle))
uvc_queue_release(&stream->queue);

+ if (handle->is_streaming)
+ uvc_pm_put(stream);
+
+#ifdef CONFIG_USB_VIDEO_CLASS_INPUT_EVDEV
+ uvc_pm_put(stream);
+#endif
+
/* Release the file handle. */
uvc_dismiss_privileges(handle);
v4l2_fh_del(&handle->vfh);
@@ -613,12 +671,6 @@ static int uvc_v4l2_release(struct file *file)
kfree(handle);
file->private_data = NULL;

- mutex_lock(&stream->dev->lock);
- if (--stream->dev->users == 0)
- uvc_status_stop(stream->dev);
- mutex_unlock(&stream->dev->lock);
-
- usb_autopm_put_interface(stream->dev->intf);
return 0;
}

@@ -842,7 +894,21 @@ static int uvc_ioctl_streamon(struct file *file, void *fh,
return -EBUSY;

mutex_lock(&stream->mutex);
+ if (!handle->is_streaming) {
+ ret = uvc_pm_get(stream);
+ if (ret)
+ goto unlock;
+ }
+
ret = uvc_queue_streamon(&stream->queue, type);
+
+ if (ret && !handle->is_streaming)
+ uvc_pm_put(stream);
+
+ if (!ret)
+ handle->is_streaming = true;
+
+unlock:
mutex_unlock(&stream->mutex);

return ret;
@@ -859,6 +925,10 @@ static int uvc_ioctl_streamoff(struct file *file, void *fh,

mutex_lock(&stream->mutex);
uvc_queue_streamoff(&stream->queue, type);
+ if (handle->is_streaming) {
+ handle->is_streaming = false;
+ uvc_pm_put(stream);
+ }
mutex_unlock(&stream->mutex);

return 0;
@@ -909,6 +979,7 @@ static int uvc_ioctl_g_input(struct file *file, void *fh, unsigned int *input)
{
struct uvc_fh *handle = fh;
struct uvc_video_chain *chain = handle->chain;
+ struct uvc_streaming *stream = handle->stream;
u8 *buf;
int ret;

@@ -922,9 +993,16 @@ static int uvc_ioctl_g_input(struct file *file, void *fh, unsigned int *input)
if (!buf)
return -ENOMEM;

+ ret = uvc_pm_get(stream);
+ if (ret) {
+ kfree(buf);
+ return ret;
+ }
+
ret = uvc_query_ctrl(chain->dev, UVC_GET_CUR, chain->selector->id,
chain->dev->intfnum, UVC_SU_INPUT_SELECT_CONTROL,
buf, 1);
+ uvc_pm_put(stream);
if (!ret)
*input = *buf - 1;

@@ -937,6 +1015,7 @@ static int uvc_ioctl_s_input(struct file *file, void *fh, unsigned int input)
{
struct uvc_fh *handle = fh;
struct uvc_video_chain *chain = handle->chain;
+ struct uvc_streaming *stream = handle->stream;
u8 *buf;
int ret;

@@ -958,10 +1037,17 @@ static int uvc_ioctl_s_input(struct file *file, void *fh, unsigned int input)
if (!buf)
return -ENOMEM;

+ ret = uvc_pm_get(stream);
+ if (ret) {
+ kfree(buf);
+ return ret;
+ }
+
*buf = input + 1;
ret = uvc_query_ctrl(chain->dev, UVC_SET_CUR, chain->selector->id,
chain->dev->intfnum, UVC_SU_INPUT_SELECT_CONTROL,
buf, 1);
+ uvc_pm_put(stream);
kfree(buf);

return ret;
@@ -972,8 +1058,15 @@ static int uvc_ioctl_queryctrl(struct file *file, void *fh,
{
struct uvc_fh *handle = fh;
struct uvc_video_chain *chain = handle->chain;
+ struct uvc_streaming *stream = handle->stream;
+ int ret;

- return uvc_query_v4l2_ctrl(chain, qc);
+ ret = uvc_pm_get(stream);
+ if (ret)
+ return ret;
+ ret = uvc_query_v4l2_ctrl(chain, qc);
+ uvc_pm_put(stream);
+ return ret;
}

static int uvc_ioctl_query_ext_ctrl(struct file *file, void *fh,
@@ -981,10 +1074,15 @@ static int uvc_ioctl_query_ext_ctrl(struct file *file, void *fh,
{
struct uvc_fh *handle = fh;
struct uvc_video_chain *chain = handle->chain;
+ struct uvc_streaming *stream = handle->stream;
struct v4l2_queryctrl qc = { qec->id };
int ret;

+ ret = uvc_pm_get(stream);
+ if (ret)
+ return ret;
ret = uvc_query_v4l2_ctrl(chain, &qc);
+ uvc_pm_put(stream);
if (ret)
return ret;

@@ -1030,6 +1128,7 @@ static int uvc_ioctl_g_ext_ctrls(struct file *file, void *fh,
{
struct uvc_fh *handle = fh;
struct uvc_video_chain *chain = handle->chain;
+ struct uvc_streaming *stream = handle->stream;
struct v4l2_ext_control *ctrl = ctrls->controls;
unsigned int i;
int ret;
@@ -1054,22 +1153,30 @@ static int uvc_ioctl_g_ext_ctrls(struct file *file, void *fh,
return 0;
}

+ ret = uvc_pm_get(stream);
+ if (ret)
+ return ret;
ret = uvc_ctrl_begin(chain);
- if (ret < 0)
+ if (ret < 0) {
+ uvc_pm_put(stream);
return ret;
+ }

for (i = 0; i < ctrls->count; ++ctrl, ++i) {
ret = uvc_ctrl_get(chain, ctrl);
if (ret < 0) {
uvc_ctrl_rollback(handle);
ctrls->error_idx = i;
+ uvc_pm_put(stream);
return ret;
}
}

ctrls->error_idx = 0;

- return uvc_ctrl_rollback(handle);
+ ret = uvc_ctrl_rollback(handle);
+ uvc_pm_put(stream);
+ return ret;
}

static int uvc_ioctl_s_try_ext_ctrls(struct uvc_fh *handle,
@@ -1078,6 +1185,7 @@ static int uvc_ioctl_s_try_ext_ctrls(struct uvc_fh *handle,
{
struct v4l2_ext_control *ctrl = ctrls->controls;
struct uvc_video_chain *chain = handle->chain;
+ struct uvc_streaming *stream = handle->stream;
unsigned int i;
int ret;

@@ -1085,9 +1193,15 @@ static int uvc_ioctl_s_try_ext_ctrls(struct uvc_fh *handle,
if (ret < 0)
return ret;

+ ret = uvc_pm_get(stream);
+ if (ret)
+ return ret;
+
ret = uvc_ctrl_begin(chain);
- if (ret < 0)
+ if (ret < 0) {
+ uvc_pm_put(stream);
return ret;
+ }

for (i = 0; i < ctrls->count; ++ctrl, ++i) {
ret = uvc_ctrl_set(handle, ctrl);
@@ -1095,6 +1209,7 @@ static int uvc_ioctl_s_try_ext_ctrls(struct uvc_fh *handle,
uvc_ctrl_rollback(handle);
ctrls->error_idx = ioctl == VIDIOC_S_EXT_CTRLS ?
ctrls->count : i;
+ uvc_pm_put(stream);
return ret;
}
}
@@ -1102,9 +1217,12 @@ static int uvc_ioctl_s_try_ext_ctrls(struct uvc_fh *handle,
ctrls->error_idx = 0;

if (ioctl == VIDIOC_S_EXT_CTRLS)
- return uvc_ctrl_commit(handle, ctrls);
+ ret = uvc_ctrl_commit(handle, ctrls);
else
- return uvc_ctrl_rollback(handle);
+ ret = uvc_ctrl_rollback(handle);
+
+ uvc_pm_put(stream);
+ return ret;
}

static int uvc_ioctl_s_ext_ctrls(struct file *file, void *fh,
@@ -1119,8 +1237,16 @@ static int uvc_ioctl_try_ext_ctrls(struct file *file, void *fh,
struct v4l2_ext_controls *ctrls)
{
struct uvc_fh *handle = fh;
+ struct uvc_streaming *stream = handle->stream;
+ int ret;
+
+ ret = uvc_pm_get(stream);
+ if (ret)
+ return ret;
+ ret = uvc_ioctl_s_try_ext_ctrls(handle, ctrls, VIDIOC_TRY_EXT_CTRLS);
+ uvc_pm_put(stream);

- return uvc_ioctl_s_try_ext_ctrls(handle, ctrls, VIDIOC_TRY_EXT_CTRLS);
+ return ret;
}

static int uvc_ioctl_querymenu(struct file *file, void *fh,
@@ -1128,8 +1254,16 @@ static int uvc_ioctl_querymenu(struct file *file, void *fh,
{
struct uvc_fh *handle = fh;
struct uvc_video_chain *chain = handle->chain;
+ struct uvc_streaming *stream = handle->stream;
+ int ret;

- return uvc_query_v4l2_menu(chain, qm);
+ ret = uvc_pm_get(stream);
+ if (ret)
+ return ret;
+ ret = uvc_query_v4l2_menu(chain, qm);
+ uvc_pm_put(stream);
+
+ return ret;
}

static int uvc_ioctl_g_selection(struct file *file, void *fh,
diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
index 143230b3275b..5958b2a54dab 100644
--- a/drivers/media/usb/uvc/uvcvideo.h
+++ b/drivers/media/usb/uvc/uvcvideo.h
@@ -720,6 +720,7 @@ enum uvc_handle_state {

struct uvc_fh {
struct v4l2_fh vfh;
+ bool is_streaming;
struct uvc_video_chain *chain;
struct uvc_streaming *stream;
enum uvc_handle_state state;
--
2.35.0.rc0.227.g00780c9af4-goog

Next message: Keith Busch: "[RFC 1/7] block: support pi with extended metadata"
Previous message: Vladimir Oltean: "Re: [RFC PATCH v7 03/16] net: dsa: tag_qca: convert to FIELD macro"
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