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Add comment about an uncorrectable DMA error sometimes observed on 

tlp(4) on Netra X1, and its workaround.

Also add membar_storestore, from OpenBSD.
This commit is contained in:
nakayama 2009-12-07 11:24:30 +00:00
parent af8f0b5c72
commit 5d49252b81
1 changed files with 12 additions and 3 deletions
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15
sys/arch/sparc64/dev/iommu.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: iommu.c,v 1.93 2009/12/07 11:18:38 nakayama Exp $ */
/* $NetBSD: iommu.c,v 1.94 2009/12/07 11:24:30 nakayama Exp $ */
/*
* Copyright (c) 1999, 2000 Matthew R. Green
@ -59,7 +59,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: iommu.c,v 1.93 2009/12/07 11:18:38 nakayama Exp $");
__KERNEL_RCSID(0, "$NetBSD: iommu.c,v 1.94 2009/12/07 11:24:30 nakayama Exp $");
#include "opt_ddb.h"
@ -349,8 +349,17 @@ iommu_remove(struct iommu_state *is, vaddr_t va, size_t len)
else
len -= PAGE_SIZE;
/* XXX Zero-ing the entry would not require RMW */
/*
* XXX Zero-ing the entry would not require RMW
*
* Disabling valid bit while a page is used by a device
* causes an uncorrectable DMA error.
* Workaround to avoid an uncorrectable DMA error is
* eliminating the next line, but the page is mapped
* until the next iommu_enter call.
*/
is->is_tsb[IOTSBSLOT(va,is->is_tsbsize)] &= ~IOTTE_V;
membar_storestore();
bus_space_write_8(is->is_bustag, is->is_iommu,
IOMMUREG(iommu_flush), va);
va += PAGE_SIZE;