Jens Axboe wrote:
On Fri, May 26 2006, zhao, forrest wrote:
For ata_piix resume operation, it first waits for BUSY bit clear,
then calls ata_device_resume().
This has the problem that it introduces scsi specific knowledge into
ata_piix, something that is both a violation and a problem because we
are moving libata away from scsi. I think the best way to currently do
this is to introduce a ata_port_ops hook (pre_resume()?) that waits for
busy clear and gets called in ata_device_resume is probably the way to
go.
ata_device_resume() is fine as-is. Modifying it to resurrect the bus is
a gross layering violation. Resume must be done in this order:
controller -> bus -> device
Thus, the bus must be resurrected and brought to a known HSM state (bus
idle), and then ata_device_resume() will work just fine.
The proper solution is to modify the pci_driver::resume code path, to
resurrect not only the HBA but also the ATA bus. Currently we have
ata_pci_device_{suspend,resume}, whose contents is wholly generic to any
random PCI device.
I would suggest creating pata_pci_device_resume(), which calls
ata_pci_device_resume(), and then waits for BSY to clear.
Similarly, create sata_pci_device_resume(), which calls
ata_pci_device_resume() then calls sata_phy_resume(). Additionally, for
select SATA controllers (sata_mv, others?), it may be wise to wait for
BSY to clear after the SATA phy has been awakened.
You are quite right that ata_piix is an inappropriate place to do all this.
Jeff
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