kernel: swap irq ack between VIC and GN4124

We ack the GN4124 **before** the VIC. The other way around makes the interrupt handling timing dependent. For instance. When the VIC VIC_CTL_EMU_LEN_W is too short it may happens that the VIC asserts the interrupt **before** the GN4124 is acked; then, so do not receive interrupts anymore from the GN4124 because it misses the VIC edge. Signed-off-by: Federico Vaga <federico.vaga@cern.ch> Signed-off-by: Michel Arruat <michel.arruat@cern.ch>

kernel: swap irq ack between VIC and GN4124
We ack the GN4124 **before** the VIC. The other way around makes the interrupt handling timing dependent. For instance. When the VIC VIC_CTL_EMU_LEN_W is too short it may happens that the VIC asserts the interrupt **before** the GN4124 is acked; then, so do not receive interrupts anymore from the GN4124 because it misses the VIC edge. Signed-off-by: Federico Vaga <federico.vaga@cern.ch> Signed-off-by: Michel Arruat <michel.arruat@cern.ch>
d56cd47c · Federico Vaga · 86b5196f · d56cd47c
Commit d56cd47c authored Nov 20, 2015 by Federico Vaga
Hide whitespace changes
Inline Side-by-side

Showing with 9 additions and 1 deletion

spec-fmc.c kernel/spec-fmc.c +9 -1

No files found.
--- a/kernel/spec-fmc.c
+++ b/kernel/spec-fmc.c
@@ -150,10 +150,18 @@ static irqreturn_t spec_vic_irq_handler(int id, void *data)
 	 */
 	spin_lock(&spec->irq_lock);
 	rv = spec_vic_irq_dispatch(spec);
+
+	/*
+	 * We ack the GN4124 **before** the VIC. The other way around makes the
+	 * interrupt handling timing dependent. For instance. When the VIC
+	 * VIC_CTL_EMU_LEN_W is too short it may happens that the VIC asserts
+	 * the interrupt **before** the GN4124 is acked; then, so do not receive
+	 * interrupts anymore from the GN4124 because it misses the VIC edge.
+	 */
+	spec_shared_irq_ack(fmc);
 	spec_vic_irq_ack(spec, 0);
 	spin_unlock(&spec->irq_lock);

-	spec_shared_irq_ack(fmc);
 	return IRQ_HANDLED;
 }