There are 2 problems on mask states in suspend/resume.
[1]:
It is better to restore the mask states of MSI/MSI-X to initial states
(MSI is unmasked, MSI-X is masked) when we release the device.
The pci_msi_shutdown() does the restoration of mask states for MSI,
while the msi_free_irqs() does it for MSI-X. In other words, in the
"disable" path both of MSI and MSI-X are handled, but in the "shutdown"
path only MSI is handled.
MSI:
pci_disable_msi()
=> pci_msi_shutdown()
[ mask states for MSI restored ]
=> msi_set_enable(dev, pos, 0);
=> msi_free_irqs()
MSI-X:
pci_disable_msix()
=> pci_msix_shutdown()
=> msix_set_enable(dev, 0);
=> msix_free_all_irqs
=> msi_free_irqs()
[ mask states for MSI-X restored ]
This patch moves the masking for MSI-X from msi_free_irqs() to
pci_msix_shutdown().
This change has some positive side effects:
- It prevents OS from touching mask states before reading preserved
bits in the register, which can be happen if msi_free_irqs() is
called from error path in msix_capability_init().
- It also prevents touching the register after turning off MSI-X in
"disable" path, which can be a problem on some devices.
[2]:
We have cache of the mask state in msi_desc, which is automatically
updated when msi/msix_mask_irq() is called. This cached states are
used for the resume.
But since what need to be restored in the resume is the states before
the shutdown on the suspend, calling msi/msix_mask_irq() from
pci_msi/msix_shutdown() is not appropriate.
This patch introduces __msi/msix_mask_irq() that do mask as same
as msi/msix_mask_irq() but does not update cached state, for use
in pci_msi/msix_shutdown().
[updated: get rid of msi/msix_mask_irq_nocache() (proposed by Matthew Wilcox)]
Reviewed-by: Matthew Wilcox <willy@linux.intel.com>
Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
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