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From: jason@lakedaemon.net (Jason Cooper)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2 02/10] irqchip: add irqchip driver for nuc900
Date: Fri, 15 Jul 2016 15:45:51 +0000	[thread overview]
Message-ID: <20160715154551.GF31509@io.lakedaemon.net> (raw)
In-Reply-To: <CAKT61h8EkOOkDHou65Uc7NNomJ6Nowvw8o6JnWxNyc0S_=x_JA@mail.gmail.com>

On Fri, Jul 15, 2016 at 05:44:50PM +0800, Wan ZongShun wrote:
> 2016-07-15 15:00 GMT+08:00 Arnd Bergmann <arnd@arndb.de>:
> > On Friday, July 15, 2016 1:15:58 PM CEST Wan Zongshun wrote:
> >>
> >> Actually, I have two choice to implement this function:
> >>
> >> option1:
> >>
> >> void __exception_irq_entry aic_handle_irq(struct pt_regs *regs)
> >> {
> >>         u32 hwirq;
> >>
> >>         (void)readl(aic_base + REG_AIC_IPER);
> >>         hwirq = readl(aic_base + REG_AIC_ISNR);
> >>
> >>         handle_IRQ((irq_find_mapping(aic_domain, hwirq)), regs);
> >> }
> >
> > (side note: I think you want handle_domain_irq())
> >
> >> option2:
> >>
> >> void __exception_irq_entry aic_handle_irq(struct pt_regs *regs)
> >> {
> >>         u32 hwirq;
> >>
> >>         hwirq = readl(aic_base + REG_AIC_IPER);
> >>         hwirq <<= 2;
> >>
> >>         handle_IRQ((irq_find_mapping(aic_domain, hwirq)), regs);
> >> }
> >>
> >> Though the option2 do shift for hwirq, but it seems better than do io
> >> operation by readl,so I prefer to option2, agree?
> >
> > That will only return an irq number that is a multiple of four, which
> > seems wrong since the numbers are not that. Did you mean to write
> >
> >         hwirq = ilog2(hwirq);   ?
> 
> Sorry, my fault, I mean hwirq >>= 2, bit[7:2] indicates which irq is triggering.
> so I have to do right shift 2 for IPER value.

Ok, this makes a lot more sense now. :)

> > That assumes that REG_AIC_IPER contains a 32-bit value with one single
> > bit set to indicate which IRQ was triggered.
> >
> > If the difference is only in performance, you could try measuring which
> > of the two ends up being faster.
> 
> It seems hard to measure. I think Do IO operation should be slower
> than shift 2. :)

Agreed.

thx,

Jason.

  parent reply	other threads:[~2016-07-15 15:45 UTC|newest]

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-07-10  7:27 [PATCH v2 00/10] ARM: NUC900: Add NUC970 SoC support Wan Zongshun
2016-07-10  7:27 ` [PATCH v2 01/10] ARM: NUC900: Add nuc970 machine support Wan Zongshun
2016-07-10 22:11   ` Arnd Bergmann
2016-07-11 16:04   ` Arnd Bergmann
2016-07-12  4:30     ` Wan Zongshun
2016-07-12  7:14       ` Wan Zongshun
2016-07-12  8:23         ` Arnd Bergmann
2016-07-10  7:27 ` [PATCH v2 02/10] irqchip: add irqchip driver for nuc900 Wan Zongshun
2016-07-10 21:51   ` Paul Gortmaker
2016-07-11  2:19     ` Wan Zongshun
2016-07-11 15:46   ` Arnd Bergmann
2016-07-12  7:04     ` Wan Zongshun
2016-07-12  8:26       ` Arnd Bergmann
2016-07-14  8:52         ` Wan Zongshun
2016-07-14 11:09           ` Arnd Bergmann
2016-07-13 20:09   ` Jason Cooper
2016-07-14  3:36     ` Wan Zongshun
2016-07-14 13:54       ` Jason Cooper
2016-07-15  5:15         ` Wan Zongshun
2016-07-15  7:00           ` Arnd Bergmann
2016-07-15  9:44             ` Wan ZongShun
2016-07-15 10:02               ` Arnd Bergmann
2016-07-21 18:45                 ` Jason Cooper
2016-07-15 15:45               ` Jason Cooper [this message]
2016-07-10  7:27 ` [PATCH v2 03/10] Clocksource: add nuc970 clocksource driver Wan Zongshun
2016-07-11 15:36   ` Arnd Bergmann
2016-07-12  7:32     ` Wan Zongshun
2016-07-12  8:28       ` Arnd Bergmann
2016-07-21 12:52         ` Daniel Lezcano
2016-07-21 12:54           ` Arnd Bergmann
2016-07-10  7:27 ` [PATCH v2 04/10] clk: add Clock driver for nuc970 Wan Zongshun
2016-07-11 22:14   ` Michael Turquette
2016-07-10  7:27 ` [PATCH v2 05/10] power/reset: Add reset driver support for nuc900 Wan Zongshun
2016-07-10 21:56   ` Paul Gortmaker
2016-07-11  2:30     ` Wan Zongshun
2016-07-11  2:58       ` Paul Gortmaker
2016-07-10  7:27 ` [PATCH v2 06/10] soc: Add SoC specific " Wan Zongshun
2016-07-11  8:03   ` Arnd Bergmann
2016-07-11  9:07     ` Wan Zongshun
2016-07-11 10:24       ` Arnd Bergmann
2016-07-11 10:28         ` Wan ZongShun
2016-07-11 10:36           ` Arnd Bergmann
2016-07-12  9:06     ` Wan Zongshun
2016-07-12  9:50       ` Arnd Bergmann
2016-07-10  7:27 ` [PATCH v2 07/10] ARM: dts: Add clock header file into dt-bindings Wan Zongshun

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