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authorDave Olson <dave.olson@qlogic.com>2007-08-10 02:18:48 +0400
committerRoland Dreier <rolandd@cisco.com>2007-10-10 07:44:20 +0400
commit9ef8617af77136e743e5dd4b081a61797888a977 (patch)
tree93999550ddf98ff3c743fd27a7bd942d8cbfdf09 /drivers/infiniband
parent1793b4771d258c93ed86a6356c95cac418781fdd (diff)
downloadlinux-9ef8617af77136e743e5dd4b081a61797888a977.tar.xz
IB/ipath: Correctly describe workaround for TID write chip bug
This is a comment change, only, correcting the comment to match the implemented workaround, rather than the original workaround, and clarifying why it's needed. Signed-off-by: Dave Olson <dave.olson@qlogic.com> Signed-off-by: Roland Dreier <rolandd@cisco.com>
Diffstat (limited to 'drivers/infiniband')
-rw-r--r--drivers/infiniband/hw/ipath/ipath_iba6120.c13
1 files changed, 8 insertions, 5 deletions
diff --git a/drivers/infiniband/hw/ipath/ipath_iba6120.c b/drivers/infiniband/hw/ipath/ipath_iba6120.c
index a324c6f7aeba..d43f0b3a43fe 100644
--- a/drivers/infiniband/hw/ipath/ipath_iba6120.c
+++ b/drivers/infiniband/hw/ipath/ipath_iba6120.c
@@ -1143,11 +1143,14 @@ static void ipath_pe_put_tid(struct ipath_devdata *dd, u64 __iomem *tidptr,
pa |= 2 << 29;
}
- /* workaround chip bug 9437 by writing each TID twice
- * and holding a spinlock around the writes, so they don't
- * intermix with other TID (eager or expected) writes
- * Unfortunately, this call can be done from interrupt level
- * for the port 0 eager TIDs, so we have to use irqsave
+ /*
+ * Workaround chip bug 9437 by writing the scratch register
+ * before and after the TID, and with an io write barrier.
+ * We use a spinlock around the writes, so they can't intermix
+ * with other TID (eager or expected) writes (the chip bug
+ * is triggered by back to back TID writes). Unfortunately, this
+ * call can be done from interrupt level for the port 0 eager TIDs,
+ * so we have to use irqsave locks.
*/
spin_lock_irqsave(&dd->ipath_tid_lock, flags);
ipath_write_kreg(dd, dd->ipath_kregs->kr_scratch, 0xfeeddeaf);