diff options
Diffstat (limited to 'drivers/usb/host')
| -rw-r--r-- | drivers/usb/host/ehci-q.c | 16 |
1 files changed, 15 insertions, 1 deletions
diff --git a/drivers/usb/host/ehci-q.c b/drivers/usb/host/ehci-q.c index 2e49de820b14..c0e752cffc68 100644 --- a/drivers/usb/host/ehci-q.c +++ b/drivers/usb/host/ehci-q.c @@ -657,6 +657,14 @@ qh_make ( type = usb_pipetype (urb->pipe); maxp = usb_maxpacket (urb->dev, urb->pipe, !is_input); + /* 1024 byte maxpacket is a hardware ceiling. High bandwidth + * acts like up to 3KB, but is built from smaller packets. + */ + if (max_packet(maxp) > 1024) { + ehci_dbg(ehci, "bogus qh maxpacket %d\n", max_packet(maxp)); + goto done; + } + /* Compute interrupt scheduling parameters just once, and save. * - allowing for high bandwidth, how many nsec/uframe are used? * - split transactions need a second CSPLIT uframe; same question @@ -757,7 +765,13 @@ qh_make ( info2 |= (EHCI_TUNE_MULT_HS << 30); } else if (type == PIPE_BULK) { info1 |= (EHCI_TUNE_RL_HS << 28); - info1 |= 512 << 16; /* usb2 fixed maxpacket */ + /* The USB spec says that high speed bulk endpoints + * always use 512 byte maxpacket. But some device + * vendors decided to ignore that, and MSFT is happy + * to help them do so. So now people expect to use + * such nonconformant devices with Linux too; sigh. + */ + info1 |= max_packet(maxp) << 16; info2 |= (EHCI_TUNE_MULT_HS << 30); } else { /* PIPE_INTERRUPT */ info1 |= max_packet (maxp) << 16; |