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author | Ben Hutchings <bhutchings@solarflare.com> | 2010-06-17 20:16:36 +0100 |
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committer | Jesse Barnes <jbarnes@virtuousgeek.org> | 2010-07-30 09:29:34 -0700 |
commit | fcd097f31a6ee207cc0c3da9cccd2a86d4334785 (patch) | |
tree | 3bd2658926e691d0eab23651e45832c2714d85f6 /drivers/pci/probe.c | |
parent | ea5f9fc5899660dd26c1ccf3fab183bd041140ee (diff) | |
download | op-kernel-dev-fcd097f31a6ee207cc0c3da9cccd2a86d4334785.zip op-kernel-dev-fcd097f31a6ee207cc0c3da9cccd2a86d4334785.tar.gz |
PCI: MSI: Remove unsafe and unnecessary hardware access
During suspend on an SMP system, {read,write}_msi_msg_desc() may be
called to mask and unmask interrupts on a device that is already in a
reduced power state. At this point memory-mapped registers including
MSI-X tables are not accessible, and config space may not be fully
functional either.
While a device is in a reduced power state its interrupts are
effectively masked and its MSI(-X) state will be restored when it is
brought back to D0. Therefore these functions can simply read and
write msi_desc::msg for devices not in D0.
Further, read_msi_msg_desc() should only ever be used to update a
previously written message, so it can always read msi_desc::msg
and never needs to touch the hardware.
Tested-by: "Michael Chan" <mchan@broadcom.com>
Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Diffstat (limited to 'drivers/pci/probe.c')
0 files changed, 0 insertions, 0 deletions