linux-kernel - Re: Why isn't IRQ shared for i2c-ocore

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

Message-ID: <20150508065747.GG16220@x1>
Date:	Fri, 8 May 2015 07:57:47 +0100
From:	Lee Jones <lee.jones@...aro.org>
To:	Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:	York Sun <yorksun@...escale.com>,
	Julia Lawall <Julia.Lawall@...6.fr>,
	Linux I2C <linux-i2c@...r.kernel.org>, wolfram@...-dreams.de,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: Why isn't IRQ shared for i2c-ocore

On Fri, 08 May 2015, Geert Uytterhoeven wrote:

> On Thu, May 7, 2015 at 9:01 AM, Lee Jones <lee.jones@...aro.org> wrote:
> >> I have a follow up question regarding interrupt. I see many I2C bus drivers
> >> request interrupt with flag = 0. Why not using IRQF_SHARED?
> >
> > Probably because that particular IRQ is only used by the I2C
> > Controller.  I'm not exactly sure that you're getting at?  Why do you
> > think it should be shared?  You should only flag it as shared if it
> > is.
> 
> However, that's something the driver can't know.
> Sharing interrupts is an integration property. The same IP core may share its
> interrupt on one SoC, and not on another.

I guess that would depend on the IP.  If this is part of an MFD, you'd
know if you only hand a single interrupt line coming into the chip or
not.  If the IP can be moved around (copy & pasted) into different
chips, then yes, that might change.

How does one share an interrupt with other drivers if all them don't
know the IRQ is shared thought?

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog
--
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/