This patch shortens the logic in xhci_endpoint_init() by moving common
calculations involving max_packet and max_burst outside the switch
statement, rather than repeating the same code in multiple
case-specific statements. It also replaces two usages of max_packet
which were clearly intended to be max_burst all along.
More importantly, it compensates for a common bug in high-speed bulk
endpoint descriptors. In many devices there is a bulk endpoint having
a wMaxPacketSize value smaller than 512, which is forbidden by the USB
spec. Some xHCI controllers can't handle this and refuse to accept
the endpoint. This patch changes the max_packet value to 512, which
allows the controller to use the endpoint properly.
In practice the bogus maxpacket size doesn't matter, because none of
the transfers sent via these endpoints are longer than the maxpacket
value anyway.
Signed-off-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Reported-and-tested-by: "Aurélien Leblond" <blablack@xxxxxxxxx>
CC: <stable@xxxxxxxxxxxxxxx>
---
Question: Should this be handled in usbcore instead? The code that
parses endpoint descriptors already warns about high-speed bulk
endpoints with maxpacket different from 512. It could easily override
the bogus values.
Also: This probably won't work in cases where the bogus maxpacket
value is _larger_ than 512. I vaguely recall seeing a device with a
bulk maxpacket size of 1024. But such an endpoint is unlikely to work
under an xHCI controller in any case, although it might work with
EHCI.
[as1678]
drivers/usb/host/xhci-mem.c | 17 +++++++++--------
1 file changed, 9 insertions(+), 8 deletions(-)
Index: usb-3.9/drivers/usb/host/xhci-mem.c
===================================================================
--- usb-3.9.orig/drivers/usb/host/xhci-mem.c
+++ usb-3.9/drivers/usb/host/xhci-mem.c
@@ -1423,15 +1423,17 @@ int xhci_endpoint_init(struct xhci_hcd *
ep_ctx->ep_info2 |= cpu_to_le32(xhci_get_endpoint_type(udev, ep));
/* Set the max packet size and max burst */
+ max_packet = GET_MAX_PACKET(usb_endpoint_maxp(&ep->desc));
+ max_burst = 0;
switch (udev->speed) {
case USB_SPEED_SUPER:
- max_packet = usb_endpoint_maxp(&ep->desc);
- ep_ctx->ep_info2 |= cpu_to_le32(MAX_PACKET(max_packet));
/* dig out max burst from ep companion desc */
- max_packet = ep->ss_ep_comp.bMaxBurst;
- ep_ctx->ep_info2 |= cpu_to_le32(MAX_BURST(max_packet));
+ max_burst = ep->ss_ep_comp.bMaxBurst;
break;
case USB_SPEED_HIGH:
+ /* Some devices get this wrong */
+ if (usb_endpoint_xfer_bulk(&ep->desc))
+ max_packet = 512;
/* bits 11:12 specify the number of additional transaction
* opportunities per microframe (USB 2.0, section 9.6.6)
*/
@@ -1439,17 +1441,16 @@ int xhci_endpoint_init(struct xhci_hcd *
usb_endpoint_xfer_int(&ep->desc)) {
max_burst = (usb_endpoint_maxp(&ep->desc)
& 0x1800) >> 11;
- ep_ctx->ep_info2 |= cpu_to_le32(MAX_BURST(max_burst));
}
- /* Fall through */
+ break;
case USB_SPEED_FULL:
case USB_SPEED_LOW:
- max_packet = GET_MAX_PACKET(usb_endpoint_maxp(&ep->desc));
- ep_ctx->ep_info2 |= cpu_to_le32(MAX_PACKET(max_packet));
break;
default:
BUG();
}
+ ep_ctx->ep_info2 |= cpu_to_le32(MAX_PACKET(max_packet) |
+ MAX_BURST(max_burst));
max_esit_payload = xhci_get_max_esit_payload(xhci, udev, ep);
ep_ctx->tx_info = cpu_to_le32(MAX_ESIT_PAYLOAD_FOR_EP(max_esit_payload));
--
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