From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Jaya Kumar" Subject: Re: [RFC 2.6.27 1/1] gpiolib: add support for batch set of pins Date: Fri, 28 Nov 2008 07:43:31 +0800 Message-ID: <45a44e480811271543t1e564201k71e7697aa472618d@mail.gmail.com> References: <12276535632759-git-send-email-jayakumar.lkml@gmail.com> <200811252015.57870.david-b@pacbell.net> <45a44e480811252151q54580e07xfa73d69596fbfaac@mail.gmail.com> <20081127200102.GB20443@uranus.ravnborg.org> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20081127200102.GB20443@uranus.ravnborg.org> Content-Disposition: inline Sender: linux-embedded-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii" To: Sam Ravnborg Cc: David Brownell , Eric Miao , Eric Miao , Haavard Skinnemoen , Philipp Zabel , Russell King , Ben Gardner , Greg KH , linux-arm-kernel@lists.arm.linux.org.uk, linux-fbdev-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org, linux-embedded@vger.kernel.org On Fri, Nov 28, 2008 at 4:01 AM, Sam Ravnborg wrote: > On Wed, Nov 26, 2008 at 12:51:27AM -0500, Jaya Kumar wrote: >> On Tue, Nov 25, 2008 at 11:15 PM, David Brownell wrote: >> > On Tuesday 25 November 2008, Eric Miao wrote: >> >> Using a bit mask will be more generic if the GPIOs are not contiguous. >> >> Yet I still doubt this will be generic enough to be added to gpiolib. >> > >> > My expectation for this kind of mechanism was that systems who need >> > to craft another parallel bus out of GPIO pins would be doing this >> > with some system-specific utility functions. >> > >> > So my "is it generic enough" question is more at the level of "Are >> > there enough Linux systems that need this sort of thing to justify >> > generic support?". I happen not to have come across the need for >> > such ganged access from Linux (yet). Whereas I've yet to use non-x86 >> > Linux systems that don't need to manipulate individual GPIO pins... >> >> I have come across the following scenarios where a bus set of gpio is useful: >> - Broadsheet E-Ink controller (uses 16-bit data bus over GPIO) >> framebuffer device (this patch is for this) >> - Apollo/Hecuba E-Ink controller (uses 8-bit data bus over GPIO) >> framebuffer device >> - 8-bit parallel IO matrix LCD controllers, such as the Samsung KS108, >> also Hitachi, etc > > We have such a system at work. And we need fast acces to the gpio pins > when updating the LCD. > I have not written/looked to deep at the code I just recall it was > a bit messy and not something I would be proud of submitting to any ML. > > Sam > Okay. Please help me understand in case I misunderstood. Are you saying the code that I posted is too messy? To me, actually I am proud of it. :-) But if some parts look messy, I'm happy to work on improving it. I will need some advice though and please advise me on which parts look messy. Thanks, jaya