From 9e31ced888d1ca49ec5be51ef295e3ce994366c4 Mon Sep 17 00:00:00 2001 From: Mauro Carvalho Chehab Date: Sun, 11 Nov 2007 01:13:49 -0300 Subject: [PATCH] V4L/DVB (6584): Fix read() method Backport read() fixes from Markus Rechberger. Signed-off-by: Mauro Carvalho Chehab --- drivers/media/video/em28xx/em28xx-video.c | 30 ++++++++++++++++++++++-------- drivers/media/video/em28xx/em28xx.h | 2 ++ 2 files changed, 24 insertions(+), 8 deletions(-) diff --git a/drivers/media/video/em28xx/em28xx-video.c b/drivers/media/video/em28xx/em28xx-video.c index f0191779a8e2..8a4d221a4fe4 100644 --- a/drivers/media/video/em28xx/em28xx-video.c +++ b/drivers/media/video/em28xx/em28xx-video.c @@ -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); diff --git a/drivers/media/video/em28xx/em28xx.h b/drivers/media/video/em28xx/em28xx.h index 3efc05d2df67..672880383de8 100644 --- a/drivers/media/video/em28xx/em28xx.h +++ b/drivers/media/video/em28xx/em28xx.h @@ -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; -- 2.11.0