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linux/drivers/media/test-drivers/vivid/vivid-kthread-out.c
Hans Verkuil 6e8c09bb8d media: vivid: fix (partially) timing issues 
The vivid driver is a bit flaky w.r.t. the kthread timing, esp. when
running inside a virtual machine.

This is caused by calling schedule_timeout_uninterruptible(1) which can
actually take more than one jiffie. A while loop with schedule() turns out
to be a lot more precise. Also, if mutex_trylock() fails, then just call
schedule() instead of schedule_timeout_uninterruptible(1). There is no need
to wait until the next jiffer, just schedule(), then try to get the lock
again.

This is still not precise enough, it is still relatively easy to get missed
frames. This really should be converted to use a proper timer, but for now
this solves the worst problems.

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
2020-11-16 10:31:08 +01:00

356 lines
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// SPDX-License-Identifier: GPL-2.0-only
/*
* vivid-kthread-out.h - video/vbi output thread support functions.
*
* Copyright 2014 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
*/
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/font.h>
#include <linux/mutex.h>
#include <linux/videodev2.h>
#include <linux/kthread.h>
#include <linux/freezer.h>
#include <linux/random.h>
#include <linux/v4l2-dv-timings.h>
#include <asm/div64.h>
#include <media/videobuf2-vmalloc.h>
#include <media/v4l2-dv-timings.h>
#include <media/v4l2-ioctl.h>
#include <media/v4l2-fh.h>
#include <media/v4l2-event.h>
#include "vivid-core.h"
#include "vivid-vid-common.h"
#include "vivid-vid-cap.h"
#include "vivid-vid-out.h"
#include "vivid-radio-common.h"
#include "vivid-radio-rx.h"
#include "vivid-radio-tx.h"
#include "vivid-sdr-cap.h"
#include "vivid-vbi-cap.h"
#include "vivid-vbi-out.h"
#include "vivid-osd.h"
#include "vivid-ctrls.h"
#include "vivid-kthread-out.h"
#include "vivid-meta-out.h"
static void vivid_thread_vid_out_tick(struct vivid_dev *dev)
{
struct vivid_buffer *vid_out_buf = NULL;
struct vivid_buffer *vbi_out_buf = NULL;
struct vivid_buffer *meta_out_buf = NULL;
dprintk(dev, 1, "Video Output Thread Tick\n");
/* Drop a certain percentage of buffers. */
if (dev->perc_dropped_buffers &&
prandom_u32_max(100) < dev->perc_dropped_buffers)
return;
spin_lock(&dev->slock);
/*
* Only dequeue buffer if there is at least one more pending.
* This makes video loopback possible.
*/
if (!list_empty(&dev->vid_out_active) &&
!list_is_singular(&dev->vid_out_active)) {
vid_out_buf = list_entry(dev->vid_out_active.next,
struct vivid_buffer, list);
list_del(&vid_out_buf->list);
}
if (!list_empty(&dev->vbi_out_active) &&
(dev->field_out != V4L2_FIELD_ALTERNATE ||
(dev->vbi_out_seq_count & 1))) {
vbi_out_buf = list_entry(dev->vbi_out_active.next,
struct vivid_buffer, list);
list_del(&vbi_out_buf->list);
}
if (!list_empty(&dev->meta_out_active)) {
meta_out_buf = list_entry(dev->meta_out_active.next,
struct vivid_buffer, list);
list_del(&meta_out_buf->list);
}
spin_unlock(&dev->slock);
if (!vid_out_buf && !vbi_out_buf && !meta_out_buf)
return;
if (vid_out_buf) {
v4l2_ctrl_request_setup(vid_out_buf->vb.vb2_buf.req_obj.req,
&dev->ctrl_hdl_vid_out);
v4l2_ctrl_request_complete(vid_out_buf->vb.vb2_buf.req_obj.req,
&dev->ctrl_hdl_vid_out);
vid_out_buf->vb.sequence = dev->vid_out_seq_count;
if (dev->field_out == V4L2_FIELD_ALTERNATE) {
/*
* The sequence counter counts frames, not fields.
* So divide by two.
*/
vid_out_buf->vb.sequence /= 2;
}
vid_out_buf->vb.vb2_buf.timestamp =
ktime_get_ns() + dev->time_wrap_offset;
vb2_buffer_done(&vid_out_buf->vb.vb2_buf, dev->dqbuf_error ?
VB2_BUF_STATE_ERROR : VB2_BUF_STATE_DONE);
dprintk(dev, 2, "vid_out buffer %d done\n",
vid_out_buf->vb.vb2_buf.index);
}
if (vbi_out_buf) {
v4l2_ctrl_request_setup(vbi_out_buf->vb.vb2_buf.req_obj.req,
&dev->ctrl_hdl_vbi_out);
v4l2_ctrl_request_complete(vbi_out_buf->vb.vb2_buf.req_obj.req,
&dev->ctrl_hdl_vbi_out);
if (dev->stream_sliced_vbi_out)
vivid_sliced_vbi_out_process(dev, vbi_out_buf);
vbi_out_buf->vb.sequence = dev->vbi_out_seq_count;
vbi_out_buf->vb.vb2_buf.timestamp =
ktime_get_ns() + dev->time_wrap_offset;
vb2_buffer_done(&vbi_out_buf->vb.vb2_buf, dev->dqbuf_error ?
VB2_BUF_STATE_ERROR : VB2_BUF_STATE_DONE);
dprintk(dev, 2, "vbi_out buffer %d done\n",
vbi_out_buf->vb.vb2_buf.index);
}
if (meta_out_buf) {
v4l2_ctrl_request_setup(meta_out_buf->vb.vb2_buf.req_obj.req,
&dev->ctrl_hdl_meta_out);
v4l2_ctrl_request_complete(meta_out_buf->vb.vb2_buf.req_obj.req,
&dev->ctrl_hdl_meta_out);
vivid_meta_out_process(dev, meta_out_buf);
meta_out_buf->vb.sequence = dev->meta_out_seq_count;
meta_out_buf->vb.vb2_buf.timestamp =
ktime_get_ns() + dev->time_wrap_offset;
vb2_buffer_done(&meta_out_buf->vb.vb2_buf, dev->dqbuf_error ?
VB2_BUF_STATE_ERROR : VB2_BUF_STATE_DONE);
dprintk(dev, 2, "meta_out buffer %d done\n",
meta_out_buf->vb.vb2_buf.index);
}
dev->dqbuf_error = false;
}
static int vivid_thread_vid_out(void *data)
{
struct vivid_dev *dev = data;
u64 numerators_since_start;
u64 buffers_since_start;
u64 next_jiffies_since_start;
unsigned long jiffies_since_start;
unsigned long cur_jiffies;
unsigned wait_jiffies;
unsigned numerator;
unsigned denominator;
dprintk(dev, 1, "Video Output Thread Start\n");
set_freezable();
/* Resets frame counters */
dev->out_seq_offset = 0;
if (dev->seq_wrap)
dev->out_seq_count = 0xffffff80U;
dev->jiffies_vid_out = jiffies;
dev->vid_out_seq_start = dev->vbi_out_seq_start = 0;
dev->meta_out_seq_start = 0;
dev->out_seq_resync = false;
for (;;) {
try_to_freeze();
if (kthread_should_stop())
break;
if (!mutex_trylock(&dev->mutex)) {
schedule();
continue;
}
cur_jiffies = jiffies;
if (dev->out_seq_resync) {
dev->jiffies_vid_out = cur_jiffies;
dev->out_seq_offset = dev->out_seq_count + 1;
dev->out_seq_count = 0;
dev->out_seq_resync = false;
}
numerator = dev->timeperframe_vid_out.numerator;
denominator = dev->timeperframe_vid_out.denominator;
if (dev->field_out == V4L2_FIELD_ALTERNATE)
denominator *= 2;
/* Calculate the number of jiffies since we started streaming */
jiffies_since_start = cur_jiffies - dev->jiffies_vid_out;
/* Get the number of buffers streamed since the start */
buffers_since_start = (u64)jiffies_since_start * denominator +
(HZ * numerator) / 2;
do_div(buffers_since_start, HZ * numerator);
/*
* After more than 0xf0000000 (rounded down to a multiple of
* 'jiffies-per-day' to ease jiffies_to_msecs calculation)
* jiffies have passed since we started streaming reset the
* counters and keep track of the sequence offset.
*/
if (jiffies_since_start > JIFFIES_RESYNC) {
dev->jiffies_vid_out = cur_jiffies;
dev->out_seq_offset = buffers_since_start;
buffers_since_start = 0;
}
dev->out_seq_count = buffers_since_start + dev->out_seq_offset;
dev->vid_out_seq_count = dev->out_seq_count - dev->vid_out_seq_start;
dev->vbi_out_seq_count = dev->out_seq_count - dev->vbi_out_seq_start;
dev->meta_out_seq_count = dev->out_seq_count - dev->meta_out_seq_start;
vivid_thread_vid_out_tick(dev);
mutex_unlock(&dev->mutex);
/*
* Calculate the number of 'numerators' streamed since we started,
* not including the current buffer.
*/
numerators_since_start = buffers_since_start * numerator;
/* And the number of jiffies since we started */
jiffies_since_start = jiffies - dev->jiffies_vid_out;
/* Increase by the 'numerator' of one buffer */
numerators_since_start += numerator;
/*
* Calculate when that next buffer is supposed to start
* in jiffies since we started streaming.
*/
next_jiffies_since_start = numerators_since_start * HZ +
denominator / 2;
do_div(next_jiffies_since_start, denominator);
/* If it is in the past, then just schedule asap */
if (next_jiffies_since_start < jiffies_since_start)
next_jiffies_since_start = jiffies_since_start;
wait_jiffies = next_jiffies_since_start - jiffies_since_start;
while (jiffies - cur_jiffies < wait_jiffies &&
!kthread_should_stop())
schedule();
}
dprintk(dev, 1, "Video Output Thread End\n");
return 0;
}
static void vivid_grab_controls(struct vivid_dev *dev, bool grab)
{
v4l2_ctrl_grab(dev->ctrl_has_crop_out, grab);
v4l2_ctrl_grab(dev->ctrl_has_compose_out, grab);
v4l2_ctrl_grab(dev->ctrl_has_scaler_out, grab);
v4l2_ctrl_grab(dev->ctrl_tx_mode, grab);
v4l2_ctrl_grab(dev->ctrl_tx_rgb_range, grab);
}
int vivid_start_generating_vid_out(struct vivid_dev *dev, bool *pstreaming)
{
dprintk(dev, 1, "%s\n", __func__);
if (dev->kthread_vid_out) {
u32 seq_count = dev->out_seq_count + dev->seq_wrap * 128;
if (pstreaming == &dev->vid_out_streaming)
dev->vid_out_seq_start = seq_count;
else if (pstreaming == &dev->vbi_out_streaming)
dev->vbi_out_seq_start = seq_count;
else
dev->meta_out_seq_start = seq_count;
*pstreaming = true;
return 0;
}
/* Resets frame counters */
dev->jiffies_vid_out = jiffies;
dev->vid_out_seq_start = dev->seq_wrap * 128;
dev->vbi_out_seq_start = dev->seq_wrap * 128;
dev->meta_out_seq_start = dev->seq_wrap * 128;
dev->kthread_vid_out = kthread_run(vivid_thread_vid_out, dev,
"%s-vid-out", dev->v4l2_dev.name);
if (IS_ERR(dev->kthread_vid_out)) {
int err = PTR_ERR(dev->kthread_vid_out);
dev->kthread_vid_out = NULL;
v4l2_err(&dev->v4l2_dev, "kernel_thread() failed\n");
return err;
}
*pstreaming = true;
vivid_grab_controls(dev, true);
dprintk(dev, 1, "returning from %s\n", __func__);
return 0;
}
void vivid_stop_generating_vid_out(struct vivid_dev *dev, bool *pstreaming)
{
dprintk(dev, 1, "%s\n", __func__);
if (dev->kthread_vid_out == NULL)
return;
*pstreaming = false;
if (pstreaming == &dev->vid_out_streaming) {
/* Release all active buffers */
while (!list_empty(&dev->vid_out_active)) {
struct vivid_buffer *buf;
buf = list_entry(dev->vid_out_active.next,
struct vivid_buffer, list);
list_del(&buf->list);
v4l2_ctrl_request_complete(buf->vb.vb2_buf.req_obj.req,
&dev->ctrl_hdl_vid_out);
vb2_buffer_done(&buf->vb.vb2_buf, VB2_BUF_STATE_ERROR);
dprintk(dev, 2, "vid_out buffer %d done\n",
buf->vb.vb2_buf.index);
}
}
if (pstreaming == &dev->vbi_out_streaming) {
while (!list_empty(&dev->vbi_out_active)) {
struct vivid_buffer *buf;
buf = list_entry(dev->vbi_out_active.next,
struct vivid_buffer, list);
list_del(&buf->list);
v4l2_ctrl_request_complete(buf->vb.vb2_buf.req_obj.req,
&dev->ctrl_hdl_vbi_out);
vb2_buffer_done(&buf->vb.vb2_buf, VB2_BUF_STATE_ERROR);
dprintk(dev, 2, "vbi_out buffer %d done\n",
buf->vb.vb2_buf.index);
}
}
if (pstreaming == &dev->meta_out_streaming) {
while (!list_empty(&dev->meta_out_active)) {
struct vivid_buffer *buf;
buf = list_entry(dev->meta_out_active.next,
struct vivid_buffer, list);
list_del(&buf->list);
v4l2_ctrl_request_complete(buf->vb.vb2_buf.req_obj.req,
&dev->ctrl_hdl_meta_out);
vb2_buffer_done(&buf->vb.vb2_buf, VB2_BUF_STATE_ERROR);
dprintk(dev, 2, "meta_out buffer %d done\n",
buf->vb.vb2_buf.index);
}
}
if (dev->vid_out_streaming || dev->vbi_out_streaming ||
dev->meta_out_streaming)
return;
/* shutdown control thread */
vivid_grab_controls(dev, false);
kthread_stop(dev->kthread_vid_out);
dev->kthread_vid_out = NULL;
}
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