From: Felipe Balbi <balbi@ti.com>
To: Jon Hunter <jon-hunter@ti.com>
Cc: balbi@ti.com, Kevin Hilman <khilman@linaro.org>,
Santosh Shilimkar <santosh.shilimkar@ti.com>,
Linus Walleij <linus.walleij@linaro.org>,
Tony Lindgren <tony@atomide.com>,
linux-omap <linux-omap@vger.kernel.org>,
linux-arm <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH 1/2] gpio/omap: convert gpio irq domain to linear mapping
Date: Mon, 4 Mar 2013 20:47:56 +0200 [thread overview]
Message-ID: <20130304184756.GA15203@arwen.pp.htv.fi> (raw)
In-Reply-To: <5134E0BF.7050306@ti.com>
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Hi,
On Mon, Mar 04, 2013 at 11:58:23AM -0600, Jon Hunter wrote:
> >>> while (isr) {
> >>> unsigned long bit = __ffs(isr);
> >>>
> >>> /* clear this bit */
> >>> isr &= ~bit;
> >>>
> >>> generic_handle_irq(irq_find_mapping(bank->domain, bit);
> >>> }
> >>>
> >>> this way you will only iterate the amount of bits enabled in the isr
> >>> register.
> >>
> >> Definitely cleaner but I am wondering which approach would be more
> >> efficient from an instruction standpoint. This could definitely be much
> >> more efficient if there is only a couple bits set.
> >
> > __ffs() is done with CLZ instruction, so it's pretty fast.
>
> Ok, yes I see that now for ARMv5 onwards. Grant has pushed the patch,
> but may be we can update this as an optimisation separately.
sure, that was my suggestion from the beginning :-) It's clearly subject
to a separate patch.
--
balbi
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next prev parent reply other threads:[~2013-03-04 18:48 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-03-01 17:22 [PATCH 0/2] gpio/omap: updates for v3.10 Jon Hunter
2013-03-01 17:22 ` [PATCH 1/2] gpio/omap: convert gpio irq domain to linear mapping Jon Hunter
2013-03-02 5:24 ` Santosh Shilimkar
2013-03-02 11:48 ` Felipe Balbi
2013-03-04 17:06 ` Jon Hunter
2013-03-04 17:11 ` Felipe Balbi
2013-03-04 17:58 ` Jon Hunter
2013-03-04 18:47 ` Felipe Balbi [this message]
2013-03-02 19:39 ` Grant Likely
2013-03-01 17:22 ` [PATCH 2/2] gpio/omap: warn if bank is not enabled on setting irq type Jon Hunter
2013-03-02 5:27 ` Santosh Shilimkar
2013-03-02 11:49 ` Felipe Balbi
2013-03-02 19:40 ` Grant Likely
2013-03-01 17:39 ` [PATCH 0/2] gpio/omap: updates for v3.10 Kevin Hilman
2013-03-01 22:52 ` Javier Martinez Canillas
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