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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
include/linux/msi.h
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@ -14,8 +14,10 @@ struct irq_desc;
extern void mask_msi_irq(unsigned int irq);
extern void unmask_msi_irq(unsigned int irq);
extern void read_msi_msg_desc(struct irq_desc *desc, struct msi_msg *msg);
extern void get_cached_msi_msg_desc(struct irq_desc *desc, struct msi_msg *msg);
extern void write_msi_msg_desc(struct irq_desc *desc, struct msi_msg *msg);
extern void read_msi_msg(unsigned int irq, struct msi_msg *msg);
extern void get_cached_msi_msg(unsigned int irq, struct msi_msg *msg);
extern void write_msi_msg(unsigned int irq, struct msi_msg *msg);
struct msi_desc {