PCI: MSI: Restore read_msi_msg_desc(); add get_cached_msi_msg_desc()
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>
diff --git a/include/linux/msi.h b/include/linux/msi.h
index 6991ab5..91b05c1 100644
--- a/include/linux/msi.h
+++ b/include/linux/msi.h
@@ -14,8 +14,10 @@
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 {