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ehci: Detect going in circles when filling the queue

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For ctrl endpoints Windows (atleast Win7) creates circular td lists, so far
these were not a problem because we would stop filling the queue if altnext
was set. Since further patches in this patchset remove the altnext check this
does become a problem and we need detection for going in circles.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
This commit is contained in:
Hans de Goede 2012-10-24 18:14:03 +02:00 committed by Gerd Hoffmann
parent 44272b0f88
commit e3a36bce1d
1 changed files with 8 additions and 1 deletions
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9
hw/usb/hcd-ehci.c
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@ -2073,7 +2073,7 @@ static int ehci_fill_queue(EHCIPacket *p)
{
EHCIQueue *q = p->queue;
EHCIqtd qtd = p->qtd;
uint32_t qtdaddr;
uint32_t qtdaddr, start_addr = p->qtdaddr;
for (;;) {
if (NLPTR_TBIT(qtd.altnext) == 0) {
@ -2083,6 +2083,13 @@ static int ehci_fill_queue(EHCIPacket *p)
break;
}
qtdaddr = qtd.next;
/*
* Detect circular td lists, Windows creates these, counting on the
* active bit going low after execution to make the queue stop.
*/
if (qtdaddr == start_addr) {
break;
}
get_dwords(q->ehci, NLPTR_GET(qtdaddr),
(uint32_t *) &qtd, sizeof(EHCIqtd) >> 2);
ehci_trace_qtd(q, NLPTR_GET(qtdaddr), &qtd);