From 32aea2680de01f539d928112150279fdeeabca00 Mon Sep 17 00:00:00 2001 From: Suman Tripathi Date: Sat, 6 Feb 2016 11:25:24 +0530 Subject: ahci_xgene: Implement the workaround to fix the missing of the edge interrupt for the HOST_IRQ_STAT. Due to H/W errata, the HOST_IRQ_STAT register misses the edge interrupt when clearing the HOST_IRQ_STAT register and hardware reporting the PORT_IRQ_STAT register happens to be at the same clock cycle. Signed-off-by: Suman Tripathi Signed-off-by: Tejun Heo --- drivers/ata/ahci_xgene.c | 47 ++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 46 insertions(+), 1 deletion(-) (limited to 'drivers/ata/ahci_xgene.c') diff --git a/drivers/ata/ahci_xgene.c b/drivers/ata/ahci_xgene.c index 8b8ccb6434e2..8e3f7faf00d3 100644 --- a/drivers/ata/ahci_xgene.c +++ b/drivers/ata/ahci_xgene.c @@ -548,6 +548,51 @@ softreset_retry: return rc; } +/** + * xgene_ahci_handle_broken_edge_irq - Handle the broken irq. + * @ata_host: Host that recieved the irq + * @irq_masked: HOST_IRQ_STAT value + * + * For hardware with broken edge trigger latch + * the HOST_IRQ_STAT register misses the edge interrupt + * when clearing of HOST_IRQ_STAT register and hardware + * reporting the PORT_IRQ_STAT register at the + * same clock cycle. + * As such, the algorithm below outlines the workaround. + * + * 1. Read HOST_IRQ_STAT register and save the state. + * 2. Clear the HOST_IRQ_STAT register. + * 3. Read back the HOST_IRQ_STAT register. + * 4. If HOST_IRQ_STAT register equals to zero, then + * traverse the rest of port's PORT_IRQ_STAT register + * to check if an interrupt is triggered at that point else + * go to step 6. + * 5. If PORT_IRQ_STAT register of rest ports is not equal to zero + * then update the state of HOST_IRQ_STAT saved in step 1. + * 6. Handle port interrupts. + * 7. Exit + */ +static int xgene_ahci_handle_broken_edge_irq(struct ata_host *host, + u32 irq_masked) +{ + struct ahci_host_priv *hpriv = host->private_data; + void __iomem *port_mmio; + int i; + + if (!readl(hpriv->mmio + HOST_IRQ_STAT)) { + for (i = 0; i < host->n_ports; i++) { + if (irq_masked & (1 << i)) + continue; + + port_mmio = ahci_port_base(host->ports[i]); + if (readl(port_mmio + PORT_IRQ_STAT)) + irq_masked |= (1 << i); + } + } + + return ahci_handle_port_intr(host, irq_masked); +} + static irqreturn_t xgene_ahci_irq_intr(int irq, void *dev_instance) { struct ata_host *host = dev_instance; @@ -576,7 +621,7 @@ static irqreturn_t xgene_ahci_irq_intr(int irq, void *dev_instance) */ writel(irq_stat, mmio + HOST_IRQ_STAT); - rc = ahci_handle_port_intr(host, irq_masked); + rc = xgene_ahci_handle_broken_edge_irq(host, irq_masked); spin_unlock(&host->lock); -- cgit v1.2.3