From: thomas.petazzoni@free-electrons.com (Thomas Petazzoni)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 3.9] Driver for 7-segment displays connected over GPIOs
Date: Mon, 7 Jan 2013 18:07:08 +0100 [thread overview]
Message-ID: <20130107180708.2ffc1540@skate> (raw)
In-Reply-To: <20130107164845.GA2911@kroah.com>
Dear Greg Kroah-Hartman,
On Mon, 7 Jan 2013 08:48:45 -0800, Greg Kroah-Hartman wrote:
> If you ever add/remove/modify sysfs files, you have to also do the same
> for the Documentation/ABI/ files as well, please redo that in this patch
> series.
Sure.
> But, the bigger question is, why is this a kernel driver at all? Can't
> you do this from userspace today without any new kernel code?
Indeed, it can be done from userspace since we're just controlling
GPIOs. Having a kernel driver allows to describe this device in the
Device Tree, like all other devices, and have it "magically" appear,
with a convenient user-space interface.
Not having a kernel driver means that gazillions of applications
re-invent the same piece of code over and over again, have to hardcode
the GPIO numbers for a given piece of hardware, while the kernel
abstract all of this very nicely.
Thanks,
Thomas
--
Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com
WARNING: multiple messages have this Message-ID (diff)
From: Thomas Petazzoni <thomas.petazzoni-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
To: Greg Kroah-Hartman
<gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org>
Cc: Lior Amsalem <alior-eYqpPyKDWXRBDgjK7y7TUQ@public.gmane.org>,
Andrew Lunn <andrew-g2DYL2Zd6BY@public.gmane.org>,
Jason Cooper <jason-NLaQJdtUoK4Be96aLqz0jA@public.gmane.org>,
devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org,
linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org
Subject: Re: [PATCH 3.9] Driver for 7-segment displays connected over GPIOs
Date: Mon, 7 Jan 2013 18:07:08 +0100 [thread overview]
Message-ID: <20130107180708.2ffc1540@skate> (raw)
In-Reply-To: <20130107164845.GA2911-U8xfFu+wG4EAvxtiuMwx3w@public.gmane.org>
Dear Greg Kroah-Hartman,
On Mon, 7 Jan 2013 08:48:45 -0800, Greg Kroah-Hartman wrote:
> If you ever add/remove/modify sysfs files, you have to also do the same
> for the Documentation/ABI/ files as well, please redo that in this patch
> series.
Sure.
> But, the bigger question is, why is this a kernel driver at all? Can't
> you do this from userspace today without any new kernel code?
Indeed, it can be done from userspace since we're just controlling
GPIOs. Having a kernel driver allows to describe this device in the
Device Tree, like all other devices, and have it "magically" appear,
with a convenient user-space interface.
Not having a kernel driver means that gazillions of applications
re-invent the same piece of code over and over again, have to hardcode
the GPIO numbers for a given piece of hardware, while the kernel
abstract all of this very nicely.
Thanks,
Thomas
--
Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com
next prev parent reply other threads:[~2013-01-07 17:07 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-07 16:42 [PATCH 3.9] Driver for 7-segment displays connected over GPIOs Thomas Petazzoni
2013-01-07 16:42 ` Thomas Petazzoni
2013-01-07 16:42 ` [PATCH 3.9 1/3] misc: new driver for GPIO-connected 7-segment displays Thomas Petazzoni
2013-01-07 16:42 ` Thomas Petazzoni
2013-01-07 19:43 ` Arnd Bergmann
2013-01-07 19:43 ` Arnd Bergmann
2013-01-07 19:58 ` Thomas Petazzoni
2013-01-07 19:58 ` Thomas Petazzoni
2013-01-07 21:41 ` Arnd Bergmann
2013-01-07 21:41 ` Arnd Bergmann
2013-02-08 22:38 ` Grant Likely
2013-02-08 22:38 ` Grant Likely
2013-02-08 22:35 ` Grant Likely
2013-02-08 22:35 ` Grant Likely
2013-01-07 16:42 ` [PATCH 3.9 2/3] arm: mvebu: add the 7-segment display DT informations to Armada 370 DB Thomas Petazzoni
2013-01-07 16:42 ` Thomas Petazzoni
2013-01-07 16:42 ` [PATCH 3.9 3/3] arm: mvebu: add the 7-segment display DT informations to Armada XP DB Thomas Petazzoni
2013-01-07 16:42 ` Thomas Petazzoni
2013-02-08 22:39 ` Grant Likely
2013-02-08 22:39 ` Grant Likely
2013-01-07 16:48 ` [PATCH 3.9] Driver for 7-segment displays connected over GPIOs Greg Kroah-Hartman
2013-01-07 16:48 ` Greg Kroah-Hartman
2013-01-07 17:07 ` Thomas Petazzoni [this message]
2013-01-07 17:07 ` Thomas Petazzoni
2013-01-07 17:23 ` Greg Kroah-Hartman
2013-01-07 17:23 ` Greg Kroah-Hartman
2013-01-07 17:40 ` Thomas Petazzoni
2013-01-07 17:40 ` Thomas Petazzoni
2013-01-07 17:43 ` Thomas Petazzoni
2013-01-07 17:43 ` Thomas Petazzoni
2013-01-07 17:56 ` H Hartley Sweeten
2013-01-07 17:56 ` H Hartley Sweeten
2013-01-07 18:02 ` Jason Cooper
2013-01-07 18:02 ` Jason Cooper
2013-01-07 18:06 ` Russell King - ARM Linux
2013-01-07 18:06 ` Russell King - ARM Linux
2013-01-07 17:53 ` Thomas Petazzoni
2013-01-07 17:53 ` Thomas Petazzoni
2013-01-07 18:36 ` Greg Kroah-Hartman
2013-01-07 18:36 ` Greg Kroah-Hartman
2013-01-07 18:38 ` Thomas Petazzoni
2013-01-07 18:38 ` Thomas Petazzoni
2013-01-07 23:05 ` Linus Walleij
2013-01-07 23:05 ` Linus Walleij
2013-02-09 16:28 ` Pavel Machek
2013-02-09 16:28 ` Pavel Machek
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