On Wed, Jul 20, 2016 at 12:13:46PM +0000, Pang Raymond wrote: > > 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. > > Signed-off-by: Raymond Pang <raymond_rule@xxxxxxxxxxx> Applied to libata/for-4.8 with minor updates to the comment. Thanks. -- tejun -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
