Re: [PATCH v2] irqchip: vt8500: Switch to a simple write clear for Interrupt Status Register
2014-04-28 18:08 GMT+08:00 Thomas Gleixner : > On Mon, 28 Apr 2014, Axel Lin wrote: > >> 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. > > Again, what's the point of this? > > There is still nothing which masks the interrupt at the controller > level which is the purpose of the irq_mask() callback. > Ah, stupid me. Let me try again to fix this. Thanks, Axel -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH v2] irqchip: vt8500: Switch to a simple write clear for Interrupt Status Register
On Mon, 28 Apr 2014, Axel Lin wrote:
> 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.
Again, what's the point of this?
There is still nothing which masks the interrupt at the controller
level which is the purpose of the irq_mask() callback.
Thanks,
tglx
> Signed-off-by: Axel Lin
> ---
> 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 majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH v2] irqchip: vt8500: Switch to a simple write clear for Interrupt Status Register
On Mon, 28 Apr 2014, Axel Lin wrote:
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.
Again, what's the point of this?
There is still nothing which masks the interrupt at the controller
level which is the purpose of the irq_mask() callback.
Thanks,
tglx
Signed-off-by: Axel Lin axel@ingics.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 majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH v2] irqchip: vt8500: Switch to a simple write clear for Interrupt Status Register
2014-04-28 18:08 GMT+08:00 Thomas Gleixner t...@linutronix.de: On Mon, 28 Apr 2014, Axel Lin wrote: 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. Again, what's the point of this? There is still nothing which masks the interrupt at the controller level which is the purpose of the irq_mask() callback. Ah, stupid me. Let me try again to fix this. Thanks, Axel -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
