From: Stefan Richter <stefanr@s5r6.in-berlin.de>
To: linux1394-devel@lists.sourceforge.net
Cc: linux-kernel@vger.kernel.org, Clemens Ladisch <clemens@ladisch.de>
Subject: [PATCH] firewire: ohci: work around VIA and NEC PHY packet reception bug
Date: Sat, 28 Aug 2010 14:21:26 +0200 (CEST) [thread overview]
Message-ID: <tkrat.8705132a95f3f284@s5r6.in-berlin.de> (raw)
In-Reply-To: <4C6909DD.3070002@ladisch.de>
VIA VT6306, VIA VT6308, and NEC OrangeLink controllers do not write
packet event codes for received PHY packets (or perhaps write
evt_no_status, hard to tell). Work around it by overwriting the
packet's ACK by ack_complete, so that upper layers that listen to PHY
packet reception get to see these packets.
(Also tested: TI TSB82AA2, TI TSB43AB22/A, TI XIO2213A, Agere FW643,
JMicron JMB381 --- these do not exhibit this bug.)
Clemens proposed a quirks flag for that, IOW whitelist known misbehaving
controllers for this workaround. Though to me it seems harmless enough
to enable for all controllers.
The log_ar_at_event() debug log will continue to show the original
status from the DMA unit.
Reported-by: Clemens Ladisch <clemens@ladisch.de> (VT6308)
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
---
drivers/firewire/ohci.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
Index: b/drivers/firewire/ohci.c
===================================================================
--- a/drivers/firewire/ohci.c
+++ b/drivers/firewire/ohci.c
@@ -694,7 +694,15 @@ static __le32 *handle_ar_packet(struct a
log_ar_at_event('R', p.speed, p.header, evt);
/*
- * The OHCI bus reset handler synthesizes a phy packet with
+ * Several controllers, notably from NEC and VIA, forget to
+ * write ack_complete status at PHY packet reception.
+ */
+ if (evt == OHCI1394_evt_no_status &&
+ (p.header[0] & 0xff) == (OHCI1394_phy_tcode << 4))
+ p.ack = ACK_COMPLETE;
+
+ /*
+ * The OHCI bus reset handler synthesizes a PHY packet with
* the new generation number when a bus reset happens (see
* section 8.4.2.3). This helps us determine when a request
* was received and make sure we send the response in the same
--
Stefan Richter
-=====-==-=- =--- ===--
http://arcgraph.de/sr/
next parent reply other threads:[~2010-08-28 12:21 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <4C6909DD.3070002@ladisch.de>
2010-08-28 12:21 ` Stefan Richter [this message]
2010-08-28 12:22 ` [PATCH] firewire: ohci: add some "unlikely" hints Stefan Richter
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