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PCI: MSI: Restore read_msi_msg_desc(); add get_cached_msi_msg_desc()

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commit 2ca1af9aa3285c6a5f103ed31ad09f7399fc65d7 "PCI: MSI: Remove
unsafe and unnecessary hardware access" changed read_msi_msg_desc() to
return the last MSI message written instead of reading it from the
device, since it may be called while the device is in a reduced
power state.

However, the pSeries platform code really does need to read messages
from the device, since they are initially written by firmware.
Therefore:
- Restore the previous behaviour of read_msi_msg_desc()
- Add new functions get_cached_msi_msg{,_desc}() which return the
  last MSI message written
- Use the new functions where appropriate

Acked-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
This commit is contained in:
Ben Hutchings
2010-07-23 14:56:28 +01:00
committed by Jesse Barnes
parent 911e1c9b05
commit 30da552428
5 changed files with 49 additions and 10 deletions
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2
arch/x86/kernel/apic/io_apic.c
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@ -3397,7 +3397,7 @@ static int set_msi_irq_affinity(unsigned int irq, const struct cpumask *mask)
cfg = desc->chip_data;
read_msi_msg_desc(desc, &msg);
get_cached_msi_msg_desc(desc, &msg);
msg.data &= ~MSI_DATA_VECTOR_MASK;
msg.data |= MSI_DATA_VECTOR(cfg->vector);