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
Signed-off-by: Frank Schäfer <fschaefer.oss@xxxxxxxxxxxxxx>
---
drivers/media/usb/em28xx/em28xx-core.c | 23 +++++++++++++++--------
1 Datei geändert, 15 Zeilen hinzugefügt(+), 8 Zeilen entfernt(-)
diff --git a/drivers/media/usb/em28xx/em28xx-core.c b/drivers/media/usb/em28xx/em28xx-core.c
index 6b588e2..06d5734 100644
--- a/drivers/media/usb/em28xx/em28xx-core.c
+++ b/drivers/media/usb/em28xx/em28xx-core.c
@@ -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);
--
1.7.10.4
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