ehci: Retry to fill the queue while waiting for td completion
If the guest is using multiple transfers to try and keep the usb bus busy / used at maximum efficiency, currently we would see / do the following: 1) submit transfer 1 to the device 2) submit transfer 2 to the device 3) report transfer 1 completion to guest 4) report transfer 2 completion to guest 5) submit transfer 1 to the device 6) report transfer 1 completion to guest 7) submit transfer 2 to the device 8) report transfer 2 completion to guest etc. So after the initial submission we would effectively only have 1 transfer in flight, rather then 2. This is caused by us not checking the queue for addition of new transfers by the guest (ie the resubmission of a recently finished transfer), while waiting for a pending transfer to complete. This patch does add a check for this, changing the sequence to: 1) submit transfer 1 to the device 2) submit transfer 2 to the device 3) report transfer 1 completion to guest 4) submit transfer 1 to the device 5) report transfer 2 completion to guest 6) submit transfer 2 to the device etc. Thus keeping 2 transfers in flight (most of the time, and always 1), as intended by the guest. Signed-off-by: Hans de Goede <hdegoede@redhat.com> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
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@ -381,7 +381,7 @@ struct EHCIQueue {
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uint32_t qhaddr; /* address QH read from */
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uint32_t qtdaddr; /* address QTD read from */
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USBDevice *dev;
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QTAILQ_HEAD(, EHCIPacket) packets;
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QTAILQ_HEAD(pkts_head, EHCIPacket) packets;
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};
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typedef QTAILQ_HEAD(EHCIQueueHead, EHCIQueue) EHCIQueueHead;
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@ -488,6 +488,7 @@ static const char *ehci_mmio_names[] = {
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static int ehci_state_executing(EHCIQueue *q);
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static int ehci_state_writeback(EHCIQueue *q);
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static int ehci_fill_queue(EHCIPacket *p);
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static const char *nr2str(const char **n, size_t len, uint32_t nr)
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{
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@ -1994,7 +1995,7 @@ static int ehci_state_fetchqtd(EHCIQueue *q)
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{
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EHCIqtd qtd;
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EHCIPacket *p;
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int again = 0;
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int again = 1;
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get_dwords(q->ehci, NLPTR_GET(q->qtdaddr), (uint32_t *) &qtd,
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sizeof(EHCIqtd) >> 2);
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@ -2022,7 +2023,6 @@ static int ehci_state_fetchqtd(EHCIQueue *q)
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p = NULL;
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}
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ehci_set_state(q->ehci, q->async, EST_HORIZONTALQH);
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again = 1;
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} else if (p != NULL) {
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switch (p->async) {
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case EHCI_ASYNC_NONE:
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@ -2031,6 +2031,9 @@ static int ehci_state_fetchqtd(EHCIQueue *q)
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ehci_set_state(q->ehci, q->async, EST_EXECUTE);
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break;
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case EHCI_ASYNC_INFLIGHT:
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/* Check if the guest has added new tds to the queue */
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again = (ehci_fill_queue(QTAILQ_LAST(&q->packets, pkts_head)) ==
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USB_RET_PROCERR) ? -1 : 1;
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/* Unfinished async handled packet, go horizontal */
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ehci_set_state(q->ehci, q->async, EST_HORIZONTALQH);
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break;
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@ -2042,13 +2045,11 @@ static int ehci_state_fetchqtd(EHCIQueue *q)
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ehci_set_state(q->ehci, q->async, EST_EXECUTING);
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break;
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}
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again = 1;
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} else {
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p = ehci_alloc_packet(q);
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p->qtdaddr = q->qtdaddr;
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p->qtd = qtd;
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ehci_set_state(q->ehci, q->async, EST_EXECUTE);
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again = 1;
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}
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return again;
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