From: Ben Gamari <bgamari.foss@gmail.com>
To: Grant Likely <grant.likely@secretlab.ca>
Cc: beagleboard <beagleboard@googlegroups.com>,
linux-omap <linux-omap@vger.kernel.org>,
David Brownell <dbrownell@users.sourceforge.net>,
Michael Hennerich <michael.hennerich@analog.com>,
spi-devel-general <spi-devel-general@lists.sourceforge.net>,
Eric Miao <eric.miao@canonical.com>
Subject: Re: [PATCH] mcspi: Add support for GPIO chip select lines
Date: Sun, 13 Feb 2011 17:07:54 -0500 [thread overview]
Message-ID: <87bp2fwptx.fsf@gmail.com> (raw)
In-Reply-To: <20110212083324.GA17755@angua.secretlab.ca>
On Sat, 12 Feb 2011 01:33:24 -0700, Grant Likely <grant.likely@secretlab.ca> wrote:
> (Sorry for the really laggy reply)
>
No worries, I was just starting to think about this again myself.
> I don't see it being that big a deal. gpio drivers are pretty
> lightweight and it is fine to have domain-specific limitations on how
> gpios for a particular "gpio controller" behave. In your example, if
> the hardware doesn't support enabling 2 CS pins at once, then you make
> a choice, either setting one when the other is already set simply does
> not work; or it could reset the other state. Either choice would be
> fine. The SPI driver must do the right thing regardless and deselect
> the previous CS line before enabling a new one.
>
Having now finally having had a chance to implement a gpio_chip driver,
I agree. It's quite simple and seems to fill the need pretty well
> The other alternative would be to implement a new SPI chipselect
> common infrastructure, but IMO, that would just end up looking like a
> duplication of the gpio infrastructure.
>
I think you are probably right. GPIO seems to be a good fit.
Patch coming shortly. I use spi_board_info.controller_data to pass the
gpio number to the controller which doesn't seem like the best way
forward, but I wasn't sure how else to proceed. Also, since the gpio
numbers are dynamically determined spi_board_info.controller_data must
be filled in at runtime, which is also a bit of a bummer (although not
easily solved as far as I can tell). Let me know what you think.
- Ben
next prev parent reply other threads:[~2011-02-13 22:08 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-01-20 19:47 (no subject) Ben Gamari
2010-01-21 0:04 ` Ben Dooks
2010-01-21 0:04 ` (no subject) Ben Dooks
2010-01-21 0:04 ` Ben Dooks
2010-01-22 15:53 ` Re: Ben Gamari
2010-01-28 4:10 ` McSPI questions pertaining to GPIO chip select support Ben Gamari
2010-01-28 4:10 ` Ben Gamari
2010-01-28 4:15 ` Bill Gatliff
2010-01-28 4:25 ` Ben Gamari
2010-01-28 4:27 ` Bill Gatliff
2010-01-28 4:33 ` jassi brar
2010-12-21 17:56 ` [RFC PATCH] GPIO chip select support for McSPI Ben Gamari
[not found] ` <1b68c6791001272033q60dd31dbif4de285cd9bac83d-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2010-01-29 0:32 ` McSPI questions pertaining to GPIO chip select support Ben Gamari
2010-01-29 1:09 ` jassi brar
[not found] ` <1b68c6791001281709l7d11da30lee486632e85b99cb-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2010-01-29 1:58 ` Ben Gamari
2010-12-21 17:56 ` [RFC PATCH] GPIO chip select support for McSPI Ben Gamari
2010-12-21 17:56 ` [PATCH] mcspi: Add support for GPIO chip select lines Ben Gamari
2010-12-21 17:56 ` Ben Gamari
2010-12-23 19:59 ` Tony Lindgren
2010-12-23 21:38 ` Grant Likely
2010-12-23 23:09 ` Ben Gamari
2010-12-24 0:37 ` Grant Likely
2010-12-24 2:27 ` Ben Gamari
2010-12-24 3:28 ` Grant Likely
2010-12-24 6:05 ` Ben Gamari
2011-02-12 8:33 ` Grant Likely
2011-02-13 22:07 ` Ben Gamari [this message]
2011-08-30 10:14 ` McSPI questions pertaining to GPIO chip select support Raju Sana
2011-08-30 13:50 ` Ben Gamari
2011-08-30 13:50 ` [PATCH] mcspi: Add support for GPIO chip select lines Ben Gamari
2011-08-30 13:52 ` [PATCH] beagledaq: Hack in cs_gpios Ben Gamari
[not found] ` <1314712343-27367-1-git-send-email-bgamari.foss-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2011-09-05 12:42 ` Raju Sana
-- strict thread matches above, loose matches on Subject: below --
2011-03-13 19:04 GPIO chip select support in McSPI Ben Gamari
2011-03-13 19:05 ` [PATCH] mcspi: Add support for GPIO chip select lines Ben Gamari
2011-03-14 19:27 ` Grant Likely
2011-03-15 2:06 ` Ben Gamari
2011-03-15 2:10 ` Grant Likely
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