From: Dave Olson Date: Thu, 9 Aug 2007 22:18:48 +0000 (-0700) Subject: IB/ipath: Correctly describe workaround for TID write chip bug X-Git-Tag: v2.6.24-rc1~1453^2~20 X-Git-Url: http://pilppa.com/gitweb/?a=commitdiff_plain;h=9ef8617af77136e743e5dd4b081a61797888a977;p=linux-2.6-omap-h63xx.git 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 Signed-off-by: Roland Dreier --- diff --git a/drivers/infiniband/hw/ipath/ipath_iba6120.c b/drivers/infiniband/hw/ipath/ipath_iba6120.c index a324c6f7aeb..d43f0b3a43f 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);