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  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]
Date:	Mon, 20 Oct 2014 13:19:12 +0300
From:	Octavian Purdila <octavian.purdila@...el.com>
To:	Alexandre Courbot <gnurou@...il.com>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Linus Walleij <linus.walleij@...aro.org>,
	Wolfram Sang <wsa@...-dreams.de>,
	Samuel Ortiz <sameo@...ux.intel.com>,
	Lee Jones <lee.jones@...aro.org>,
	Arnd Bergmann <arnd@...db.de>, Johan Hovold <johan@...nel.org>,
	Daniel Baluta <daniel.baluta@...el.com>,
	Laurentiu Palcu <laurentiu.palcu@...el.com>,
	"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	"linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
	"linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>
Subject: Re: [PATCH v8 3/4] gpiolib: add irq_not_threaded flag to gpio_chip

On Mon, Oct 20, 2014 at 8:08 AM, Alexandre Courbot <gnurou@...il.com> wrote:
>
> On Wed, Oct 15, 2014 at 11:48 PM, Octavian Purdila
> <octavian.purdila@...el.com> wrote:
> > Some GPIO chips (e.g. the DLN2 USB adapter) have blocking get/set
> > operation but do not need a threaded irq handler.
>
> Sorry if you already explained this (I have been a little bit late
> with the GPIO reviews recently), but does this optimization bring a
> significant benefit that justifies adding another field in struct
> gpio_chip? If so it would be nice to have it in the commit message. If
> not, do we need this at all?

Hi Alexandre,

In the case DLN2 USB GPIO adapter the GPIO interrupt is generated in
the completion routine of a receive URB, which means that we are in
interrupt context. If a threaded irq is used, we would have to
schedule work instead of running to interrupt handler directly which
is unnecessary and adds latency.

BTW, AFAIC Linus W already merged this patch in his next tree, I am
keeping it in this series because it was not pulled in the mfd-next
tree.

Thanks,
Tavi
--
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/

Powered by blists - more mailing lists