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[Qemu-devel] [PULL 2/7] ohci: Clear the interrupt counter for erroneous
From: |
Gerd Hoffmann |
Subject: |
[Qemu-devel] [PULL 2/7] ohci: Clear the interrupt counter for erroneous transfers |
Date: |
Tue, 21 Aug 2018 11:11:43 +0200 |
From: Sebastian Bauer <address@hidden>
This is mandated by the ohci specification. It tells at 6.4.4 on page 104
that for transfer descriptors that are retired with an error the done
queue interrupt counter is cleared as if the interrupt delay field of the
descriptions were zero.
Before this change, error conditions were handled similarly to the
successful condition which is especially troublesome for control transfers.
Some drivers (e.g., the AmigaOS-one) as well as the example code in the
spec, set the setup stage with an interrupt delay of seven (which means no
interrupt). This is fine under normal conditions, because one usually
doesn't want to be notified about the completion of this stage. However, if
an error occurs in this stage, these drivers will not get notified with the
current implementation. The fix addresses this by following the spec more
closely. Also, otherwise, the ability to set interrupt delay to seven would
be useless.
Note that Linux drivers that I looked at don't seem to be affected as they
set six as the interrupt delay presumably for the reason that they won't
get notified otherwise.
Signed-off-by: Sebastian Bauer <address@hidden>
Message-id: address@hidden
Signed-off-by: Gerd Hoffmann <address@hidden>
---
hw/usb/hcd-ohci.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/hw/usb/hcd-ohci.c b/hw/usb/hcd-ohci.c
index d4c0293db5..98da5f0f04 100644
--- a/hw/usb/hcd-ohci.c
+++ b/hw/usb/hcd-ohci.c
@@ -1156,6 +1156,9 @@ static int ohci_service_td(OHCIState *ohci, struct
ohci_ed *ed)
OHCI_SET_BM(td.flags, TD_EC, 3);
break;
}
+ /* An error occured so we have to clear the interrupt counter. See
+ * spec at 6.4.4 on page 104 */
+ ohci->done_count = 0;
}
ed->head |= OHCI_ED_H;
}
--
2.9.3
- [Qemu-devel] [PULL 0/7] Usb 20180821 patches, Gerd Hoffmann, 2018/08/21
- [Qemu-devel] [PULL 1/7] docs/usb2.txt: ehci has six ports, Gerd Hoffmann, 2018/08/21
- [Qemu-devel] [PULL 2/7] ohci: Clear the interrupt counter for erroneous transfers,
Gerd Hoffmann <=
- [Qemu-devel] [PULL 3/7] dev-mtp: add support for canceling transaction, Gerd Hoffmann, 2018/08/21
- [Qemu-devel] [PULL 7/7] dev-mtp: rename x-root to rootdir, Gerd Hoffmann, 2018/08/21
- [Qemu-devel] [PULL 4/7] dev-mtp: fix buffer allocation for writing file contents, Gerd Hoffmann, 2018/08/21
- [Qemu-devel] [PULL 6/7] dev-mtp: Add support for > 4GB file transfers, Gerd Hoffmann, 2018/08/21
- [Qemu-devel] [PULL 5/7] dev-mtp: retry write for incomplete transfers, Gerd Hoffmann, 2018/08/21
- Re: [Qemu-devel] [PULL 0/7] Usb 20180821 patches, Peter Maydell, 2018/08/23