From: Sergei Shtylyov <sshtylyov@xxxxxxxxxxxxx>
Remove wrongly applied upper limit on the interrupt transfer
interval for low speed devices (not much of an error per se,
according to USB specs).
Signed-off-by: Sergei Shtylyov <sshtylyov@xxxxxxxxxxxxx>
Signed-off-by: David Brownell <dbrownell@xxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
---
drivers/usb/musb/musb_host.c | 18 ++++++++++--------
1 files changed, 10 insertions(+), 8 deletions(-)
diff --git a/drivers/usb/musb/musb_host.c b/drivers/usb/musb/musb_host.c
index 23d3890..6dbbd07 100644
--- a/drivers/usb/musb/musb_host.c
+++ b/drivers/usb/musb/musb_host.c
@@ -1863,19 +1863,21 @@ static int musb_urb_enqueue(
}
qh->type_reg = type_reg;
- /* precompute rxinterval/txinterval register */
- interval = min((u8)16, epd->bInterval); /* log encoding */
+ /* Precompute RXINTERVAL/TXINTERVAL register */
switch (qh->type) {
case USB_ENDPOINT_XFER_INT:
- /* fullspeed uses linear encoding */
- if (USB_SPEED_FULL == urb->dev->speed) {
- interval = epd->bInterval;
- if (!interval)
- interval = 1;
+ /*
+ * Full/low speeds use the linear encoding,
+ * high speed uses the logarithmic encoding.
+ */
+ if (urb->dev->speed <= USB_SPEED_FULL) {
+ interval = max_t(u8, epd->bInterval, 1);
+ break;
}
/* FALLTHROUGH */
case USB_ENDPOINT_XFER_ISOC:
- /* iso always uses log encoding */
+ /* ISO always uses logarithmic encoding */
+ interval = min_t(u8, epd->bInterval, 16);
break;
default:
/* REVISIT we actually want to use NAK limits, hinting to the
--
1.6.0.2
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