From 0516900adfa1955f91f1c310f9a2fa857949de1c Mon Sep 17 00:00:00 2001 From: Pang Raymond Date: Wed, 20 Jul 2016 12:13:46 +0000 Subject: [PATCH] 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 Signed-off-by: Tejun Heo --- drivers/ata/libahci.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/drivers/ata/libahci.c b/drivers/ata/libahci.c index 3e69c20e9d03..7461a587b39b 100644 --- a/drivers/ata/libahci.c +++ b/drivers/ata/libahci.c @@ -2392,12 +2392,20 @@ static int ahci_port_start(struct ata_port *ap) static void ahci_port_stop(struct ata_port *ap) { const char *emsg = NULL; + struct ahci_host_priv *hpriv = ap->host->private_data; + void __iomem *host_mmio = hpriv->mmio; int rc; /* de-initialize port */ rc = ahci_deinit_port(ap, &emsg); if (rc) ata_port_warn(ap, "%s (%d)\n", emsg, rc); + + /* + * Clear GHC.IS to prevent stuck INTx after disabling MSI and + * re-enabling INTx. + */ + writel(1 << ap->port_no, host_mmio + HOST_IRQ_STAT); } void ahci_print_info(struct ata_host *host, const char *scc_s) -- 2.20.1