diff options
| -rw-r--r-- | drivers/media/usb/em28xx/em28xx-core.c | 43 |
1 files changed, 22 insertions, 21 deletions
diff --git a/drivers/media/usb/em28xx/em28xx-core.c b/drivers/media/usb/em28xx/em28xx-core.c index ee00f9e23420..aaedd11791f2 100644 --- a/drivers/media/usb/em28xx/em28xx-core.c +++ b/drivers/media/usb/em28xx/em28xx-core.c @@ -813,12 +813,12 @@ int em28xx_resolution_set(struct em28xx *dev) /* Set USB alternate setting for analog video */ int em28xx_set_alternate(struct em28xx *dev) { - int errCode, prev_alt = dev->alt; + int errCode; int i; unsigned int min_pkt_size = dev->width * 2 + 4; /* NOTE: for isoc transfers, only alt settings > 0 are allowed - for bulk transfers, use alt=0 as default value */ + bulk transfers seem to work only with alt=0 ! */ dev->alt = 0; if ((alt > 0) && (alt < dev->num_alt)) { em28xx_coredbg("alternate forced to %d\n", dev->alt); @@ -849,25 +849,26 @@ int em28xx_set_alternate(struct em28xx *dev) } set_alt: - if (dev->alt != prev_alt) { - if (dev->analog_xfer_bulk) { - dev->max_pkt_size = 512; /* USB 2.0 spec */ - dev->packet_multiplier = EM28XX_BULK_PACKET_MULTIPLIER; - } else { /* isoc */ - em28xx_coredbg("minimum isoc packet size: %u (alt=%d)\n", - min_pkt_size, dev->alt); - dev->max_pkt_size = - dev->alt_max_pkt_size_isoc[dev->alt]; - dev->packet_multiplier = EM28XX_NUM_ISOC_PACKETS; - } - em28xx_coredbg("setting alternate %d with wMaxPacketSize=%u\n", - dev->alt, dev->max_pkt_size); - errCode = usb_set_interface(dev->udev, 0, dev->alt); - if (errCode < 0) { - em28xx_errdev("cannot change alternate number to %d (error=%i)\n", - dev->alt, errCode); - return errCode; - } + /* NOTE: for bulk transfers, we need to call usb_set_interface() + * even if the previous settings were the same. Otherwise streaming + * fails with all urbs having status = -EOVERFLOW ! */ + if (dev->analog_xfer_bulk) { + dev->max_pkt_size = 512; /* USB 2.0 spec */ + dev->packet_multiplier = EM28XX_BULK_PACKET_MULTIPLIER; + } else { /* isoc */ + em28xx_coredbg("minimum isoc packet size: %u (alt=%d)\n", + min_pkt_size, dev->alt); + dev->max_pkt_size = + dev->alt_max_pkt_size_isoc[dev->alt]; + dev->packet_multiplier = EM28XX_NUM_ISOC_PACKETS; + } + em28xx_coredbg("setting alternate %d with wMaxPacketSize=%u\n", + dev->alt, dev->max_pkt_size); + errCode = usb_set_interface(dev->udev, 0, dev->alt); + if (errCode < 0) { + em28xx_errdev("cannot change alternate number to %d (error=%i)\n", + dev->alt, errCode); + return errCode; } return 0; } |