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V4L/DVB (6584): Fix read() method

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Backport read() fixes from Markus Rechberger.

Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
This commit is contained in:
Mauro Carvalho Chehab 2007-11-11 01:13:49 -03:00
parent a225452ef8
commit 9e31ced888
2 changed files with 24 additions and 8 deletions
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30
drivers/media/video/em28xx/em28xx-video.c
View File

@ -416,6 +416,9 @@ em28xx_v4l2_read(struct file *filp, char __user * buf, size_t count,
struct em28xx_fh *fh = filp->private_data;
struct em28xx *dev = fh->dev;
/* FIXME: read() is not prepared to allow changing the video
resolution while streaming. Seems a bug at em28xx_set_fmt
*/
if (unlikely(res_get(fh) < 0))
return -EBUSY;
@ -498,25 +501,36 @@ em28xx_v4l2_read(struct file *filp, char __user * buf, size_t count,
mutex_unlock(&dev->lock);
return -ENODEV;
}
dev->video_bytesread = 0;
}
f = list_entry(dev->outqueue.prev, struct em28xx_frame_t, frame);
spin_lock_irqsave(&dev->queue_lock, lock_flags);
list_for_each_entry(i, &dev->outqueue, frame)
i->state = F_UNUSED;
INIT_LIST_HEAD(&dev->outqueue);
spin_unlock_irqrestore(&dev->queue_lock, lock_flags);
em28xx_queue_unusedframes(dev);
if (count > f->buf.length)
count = f->buf.length;
if (copy_to_user(buf, f->bufmem, count)) {
mutex_unlock(&dev->lock);
if ((dev->video_bytesread + count) > dev->frame_size)
count = dev->frame_size - dev->video_bytesread;
if (copy_to_user(buf, f->bufmem+dev->video_bytesread, count)) {
em28xx_err("Error while copying to user\n");
return -EFAULT;
}
dev->video_bytesread += count;
if (dev->video_bytesread == dev->frame_size) {
spin_lock_irqsave(&dev->queue_lock, lock_flags);
list_for_each_entry(i, &dev->outqueue, frame)
i->state = F_UNUSED;
INIT_LIST_HEAD(&dev->outqueue);
spin_unlock_irqrestore(&dev->queue_lock, lock_flags);
em28xx_queue_unusedframes(dev);
dev->video_bytesread = 0;
}
*f_pos += count;
mutex_unlock(&dev->lock);

2
drivers/media/video/em28xx/em28xx.h
View File

@ -260,6 +260,7 @@ struct em28xx {
int vscale; /* vertical scale factor (see datasheet) */
int interlaced; /* 1=interlace fileds, 0=just top fileds */
int type;
unsigned int video_bytesread; /* Number of bytes read */
unsigned long hash; /* eeprom hash - for boards with generic ID */
unsigned long i2c_hash; /* i2c devicelist hash - for boards with generic ID */
@ -268,6 +269,7 @@ struct em28xx {
enum em28xx_dev_state state;
enum em28xx_stream_state stream;
enum em28xx_io_method io;
/* locks */
struct mutex lock;
spinlock_t queue_lock;