118 lines
4.7 KiB
Diff
118 lines
4.7 KiB
Diff
From 35f2ecb66299e63a76e51e6758c517cf1394c8f9 Mon Sep 17 00:00:00 2001
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From: Hans de Goede <hdegoede@redhat.com>
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Date: Thu, 1 Mar 2012 23:55:11 +0100
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Subject: [PATCH] usb-ehci: Fix and simplify nakcnt handling
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The nakcnt code in ehci_execute_complete() marked transactions as finished
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when a packet completed with a result of USB_RET_NAK, but USB_RET_NAK
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means that the device cannot receive / send data at that time and that
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the transaction should be retried later, which is also what the usb-uhci
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and usb-ohci code does.
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Note that there already was some special code in place to handle this
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for interrupt endpoints in the form of doing a return from
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ehci_execute_complete() when reload == 0, but that for bulk transactions
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this was not handled correctly (where as for example the usb-ccid device does
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return USB_RET_NAK for bulk packets).
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Besides that the code in ehci_execute_complete() decrement nakcnt by 1
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on a packet result of USB_RET_NAK, but
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-since the transaction got marked as finished,
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nakcnt would never be decremented again
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-there is no code checking for nakcnt becoming 0
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-there is no use in re-trying the transaction within the same usb frame /
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usb-ehci frame-timer call, since the status of emulated devices won't change
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as long as the usb-ehci frame-timer is running
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So we should simply set the nakcnt to 0 when we get a USB_RET_NAK, thus
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claiming that we've tried reload times (or as many times as possible if
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reload is 0).
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Besides the code in ehci_execute_complete() handling USB_RET_NAK there
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was also code handling it in ehci_state_executing(), which calls
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ehci_execute_complete(), and then does its own handling on top of the handling
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in ehci_execute_complete(), this code would decrement nakcnt *again* (if not
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already 0), or restore the reload value (which was never changed) on success.
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Since the double decrement was wrong to begin with, and is no longer needed
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now that we set nakcnt directly to 0 on USB_RET_NAK, and the restore of reload
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is not needed either, this patch simply removes all nakcnt handling from
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ehci_state_executing().
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Signed-off-by: Hans de Goede <hdegoede@redhat.com>
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---
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hw/usb-ehci.c | 32 ++++----------------------------
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1 file changed, 4 insertions(+), 28 deletions(-)
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diff --git a/hw/usb-ehci.c b/hw/usb-ehci.c
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index 92cdf2a..aa6fae5 100644
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--- a/hw/usb-ehci.c
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+++ b/hw/usb-ehci.c
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@@ -1269,8 +1269,6 @@ static void ehci_async_complete_packet(USBPort *port, USBPacket *packet)
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static void ehci_execute_complete(EHCIQueue *q)
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{
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- int reload;
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-
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assert(q->async != EHCI_ASYNC_INFLIGHT);
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q->async = EHCI_ASYNC_NONE;
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@@ -1289,16 +1287,8 @@ static void ehci_execute_complete(EHCIQueue *q)
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ehci_record_interrupt(q->ehci, USBSTS_ERRINT);
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break;
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case USB_RET_NAK:
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- /* 4.10.3 */
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- reload = get_field(q->qh.epchar, QH_EPCHAR_RL);
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- if ((q->pid == USB_TOKEN_IN) && reload) {
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- int nakcnt = get_field(q->qh.altnext_qtd, QH_ALTNEXT_NAKCNT);
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- nakcnt--;
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- set_field(&q->qh.altnext_qtd, nakcnt, QH_ALTNEXT_NAKCNT);
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- } else if (!reload) {
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- return;
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- }
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- break;
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+ set_field(&q->qh.altnext_qtd, 0, QH_ALTNEXT_NAKCNT);
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+ return; /* We're not done yet with this transaction */
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case USB_RET_BABBLE:
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q->qh.token |= (QTD_TOKEN_HALT | QTD_TOKEN_BABBLE);
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ehci_record_interrupt(q->ehci, USBSTS_ERRINT);
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@@ -1331,7 +1321,7 @@ static void ehci_execute_complete(EHCIQueue *q)
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q->qh.token ^= QTD_TOKEN_DTOGGLE;
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q->qh.token &= ~QTD_TOKEN_ACTIVE;
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- if ((q->usb_status != USB_RET_NAK) && (q->qh.token & QTD_TOKEN_IOC)) {
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+ if (q->qh.token & QTD_TOKEN_IOC) {
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ehci_record_interrupt(q->ehci, USBSTS_INT);
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}
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}
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@@ -1905,7 +1895,6 @@ out:
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static int ehci_state_executing(EHCIQueue *q, int async)
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{
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int again = 0;
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- int reload, nakcnt;
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ehci_execute_complete(q);
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if (q->usb_status == USB_RET_ASYNC) {
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@@ -1925,21 +1914,8 @@ static int ehci_state_executing(EHCIQueue *q, int async)
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// counter decrements to 0
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}
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- reload = get_field(q->qh.epchar, QH_EPCHAR_RL);
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- if (reload) {
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- nakcnt = get_field(q->qh.altnext_qtd, QH_ALTNEXT_NAKCNT);
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- if (q->usb_status == USB_RET_NAK) {
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- if (nakcnt) {
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- nakcnt--;
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- }
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- } else {
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- nakcnt = reload;
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- }
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- set_field(&q->qh.altnext_qtd, nakcnt, QH_ALTNEXT_NAKCNT);
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- }
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-
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/* 4.10.5 */
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- if ((q->usb_status == USB_RET_NAK) || (q->qh.token & QTD_TOKEN_ACTIVE)) {
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+ if (q->usb_status == USB_RET_NAK) {
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ehci_set_state(q->ehci, async, EST_HORIZONTALQH);
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} else {
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ehci_set_state(q->ehci, async, EST_WRITEBACK);
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