linux-kernel - [PATCH v2] irqchip: vt8500: Switch to a simple write clear for Interrupt Status Register

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <1398656117.19333.1.camel@phoenix>
Date:	Mon, 28 Apr 2014 11:35:17 +0800
From:	Axel Lin <axel.lin@...ics.com>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	Tony Prisk <linux@...sktech.co.nz>, linux-kernel@...r.kernel.org
Subject: [PATCH v2] irqchip: vt8500: Switch to a simple write clear for
 Interrupt Status Register

According to the datasheet, the attribute of Interrupt Status Register is RW0S,
which means:
	Software can read the register.
	Software can also "write 1 to clear". "write 0" has no effect.

So the read/modify/write cycle is no necessary, switch to a simple write clear
instead.

Signed-off-by: Axel Lin <axel.lin@...ics.com>
---
v2: Update commit log, this is a code simplification rather than bug fix.
 drivers/irqchip/irq-vt8500.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/drivers/irqchip/irq-vt8500.c b/drivers/irqchip/irq-vt8500.c
index eb6e91e..a0085bc 100644
--- a/drivers/irqchip/irq-vt8500.c
+++ b/drivers/irqchip/irq-vt8500.c
@@ -87,14 +87,10 @@ static void vt8500_irq_mask(struct irq_data *d)
 	void __iomem *base = priv->base;
 	void __iomem *stat_reg = base + VT8500_ICIS + (d->hwirq < 32 ? 0 : 4);
 	u8 edge, dctr;
-	u32 status;
 
 	edge = readb(base + VT8500_ICDC + d->hwirq) & VT8500_EDGE;
 	if (edge) {
-		status = readl(stat_reg);
-
-		status |= (1 << (d->hwirq & 0x1f));
-		writel(status, stat_reg);
+		writel(BIT(d->hwirq & 0x1f), stat_reg);
 	} else {
 		dctr = readb(base + VT8500_ICDC + d->hwirq);
 		dctr &= ~VT8500_INT_ENABLE;
-- 
1.8.3.2



--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/