linux-kernel - [PATCH] irqchip/versatile-fpga: Handle chained IRQs properly

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Message-Id: <20200318170904.1461278-1-mans0n@gorani.run>
Date:   Thu, 19 Mar 2020 02:09:04 +0900
From:   Sungbo Eo <mans0n@...ani.run>
To:     linux-oxnas@...ups.io, Linus Walleij <linus.walleij@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Jason Cooper <jason@...edaemon.net>,
        Marc Zyngier <maz@...nel.org>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc:     Sungbo Eo <mans0n@...ani.run>,
        Neil Armstrong <narmstrong@...libre.com>
Subject: [PATCH] irqchip/versatile-fpga: Handle chained IRQs properly

Enclose the chained handler with chained_irq_{enter,exit}(), so that the
muxed interrupts get properly acked.

This patch also fixes a reboot bug on OX820 SoC, where the jiffies timer
interrupt is never acked. The kernel waits a clock tick forever in
calibrate_delay_converge(), which leads to a boot hang.

Signed-off-by: Sungbo Eo <mans0n@...ani.run>
Cc: Neil Armstrong <narmstrong@...libre.com>
---
 drivers/irqchip/irq-versatile-fpga.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/irqchip/irq-versatile-fpga.c b/drivers/irqchip/irq-versatile-fpga.c
index 928858dada75..08faab2fec3e 100644
--- a/drivers/irqchip/irq-versatile-fpga.c
+++ b/drivers/irqchip/irq-versatile-fpga.c
@@ -6,6 +6,7 @@
 #include <linux/irq.h>
 #include <linux/io.h>
 #include <linux/irqchip.h>
+#include <linux/irqchip/chained_irq.h>
 #include <linux/irqchip/versatile-fpga.h>
 #include <linux/irqdomain.h>
 #include <linux/module.h>
@@ -68,12 +69,15 @@ static void fpga_irq_unmask(struct irq_data *d)
 
 static void fpga_irq_handle(struct irq_desc *desc)
 {
+	struct irq_chip *chip = irq_desc_get_chip(desc);
 	struct fpga_irq_data *f = irq_desc_get_handler_data(desc);
 	u32 status = readl(f->base + IRQ_STATUS);
 
+	chained_irq_enter(chip, desc);
+
 	if (status == 0) {
 		do_bad_IRQ(desc);
-		return;
+		goto out;
 	}
 
 	do {
@@ -82,6 +86,9 @@ static void fpga_irq_handle(struct irq_desc *desc)
 		status &= ~(1 << irq);
 		generic_handle_irq(irq_find_mapping(f->domain, irq));
 	} while (status);
+
+out:
+	chained_irq_exit(chip, desc);
 }
 
 /*
-- 
2.25.1