Commits
Pang Raymond committed 0516900adfa
AHCI: Clear GHC.IS to prevent unexpectly asserting INTx Due to PCI subsystem behaviour, unloading AHCI driver will disable MSI and enable INTx. When HBA supports MSIx or Multiple MSI, Driver's irq handler doesn't clear GHC.IS register. It works well when reading or writing data and GHC.IS is always non-zero. But when unloading driver (or any other operation which causes disable MSIx and enable INTx), PCI subsystem uses config write(Rx04.bit10) to enable INTx. Because GHC.IS is non-zero, HBA will falsely assume some port needs interrupt service. Then it asserts INTx. To make things worse, when AHCI controller shares the same interrupt pin with other PCI device, that PCI device's ISR will be called and nobody de-asserts previous INTx. This patch clears GHC.IS in ahci_port_stop() even when using MSIx or MMSI to prevent this case. It ensures GHC.IS is zero before PCI subsystem enables INTx. tj: Minor updates to the comment. Signed-off-by: Raymond Pang <raymond_rule@hotmail.com> Signed-off-by: Tejun Heo <tj@kernel.org>