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[media] em28xx: set USB alternate settings for analog video bulk transfers properly 

Extend function em28xx_set_alternate:
- use alternate setting 0 for bulk transfers as default
- respect module parameter 'alt'=0 for bulk transfers
- set max_packet_size to 512 bytes for bulk transfers
[mchehab@redhat.com: Fix a CodingStyle issue: don't break strings
 into separate lines]
Signed-off-by: Frank Schäfer <fschaefer.oss@googlemail.com>

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
This commit is contained in:
Frank Schaefer 2012-11-08 14:11:51 -03:00 committed by Mauro Carvalho Chehab
parent 7312f2c9fa
commit c8e9d95b41
1 changed files with 15 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

23
drivers/media/usb/em28xx/em28xx-core.c
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@ -805,21 +805,23 @@ int em28xx_resolution_set(struct em28xx *dev)
return em28xx_scaler_set(dev, dev->hscale, dev->vscale);
}
/* Set USB alternate setting for analog video */
int em28xx_set_alternate(struct em28xx *dev)
{
int errCode, prev_alt = dev->alt;
int i;
unsigned int min_pkt_size = dev->width * 2 + 4;
/*
* alt = 0 is used only for control messages, so, only values
* greater than 0 can be used for streaming.
*/
if (alt && alt < dev->num_alt) {
/* NOTE: for isoc transfers, only alt settings > 0 are allowed
for bulk transfers, use alt=0 as default value */
dev->alt = 0;
if ((alt > 0) && (alt < dev->num_alt)) {
em28xx_coredbg("alternate forced to %d\n", dev->alt);
dev->alt = alt;
goto set_alt;
}
if (dev->analog_xfer_bulk)
goto set_alt;
/* When image size is bigger than a certain value,
the frame size should be increased, otherwise, only
@ -843,9 +845,14 @@ int em28xx_set_alternate(struct em28xx *dev)
set_alt:
if (dev->alt != prev_alt) {
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];
if (dev->analog_xfer_bulk) {
dev->max_pkt_size = 512; /* USB 2.0 spec */
} 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];
}
em28xx_coredbg("setting alternate %d with wMaxPacketSize=%u\n",
dev->alt, dev->max_pkt_size);
errCode = usb_set_interface(dev->udev, 0, dev->alt);