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-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);
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