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authorBen Hutchings <bhutchings@solarflare.com>2008-12-23 03:08:29 +0000
committerJesse Barnes <jbarnes@virtuousgeek.org>2009-01-07 11:13:23 -0800
commit6a479079c07211bf348ac8a79754f26bea258f26 (patch)
tree1587c0ed9446c7d0d6ab8a38d1524132e2faae35 /Documentation/PCI
parentb8d9cb2a2226118fd71f657c80b06b670a653022 (diff)
downloadop-kernel-dev-6a479079c07211bf348ac8a79754f26bea258f26.zip
op-kernel-dev-6a479079c07211bf348ac8a79754f26bea258f26.tar.gz
PCI: Add pci_clear_master() as opposite of pci_set_master()
During an online device reset it may be useful to disable bus-mastering. pci_disable_device() does that, and far more besides, so is not suitable for an online reset. Add pci_clear_master() which does just this. Signed-off-by: Ben Hutchings <bhutchings@solarflare.com> Reviewed-by: Matthew Wilcox <willy@linux.intel.com> Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Diffstat (limited to 'Documentation/PCI')
-rw-r--r--Documentation/PCI/pci.txt3
1 files changed, 2 insertions, 1 deletions
diff --git a/Documentation/PCI/pci.txt b/Documentation/PCI/pci.txt
index fd4907a..7f6de6e 100644
--- a/Documentation/PCI/pci.txt
+++ b/Documentation/PCI/pci.txt
@@ -294,7 +294,8 @@ NOTE: pci_enable_device() can fail! Check the return value.
pci_set_master() will enable DMA by setting the bus master bit
in the PCI_COMMAND register. It also fixes the latency timer value if
-it's set to something bogus by the BIOS.
+it's set to something bogus by the BIOS. pci_clear_master() will
+disable DMA by clearing the bus master bit.
If the PCI device can use the PCI Memory-Write-Invalidate transaction,
call pci_set_mwi(). This enables the PCI_COMMAND bit for Mem-Wr-Inval
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