linux-spi.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
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

  reply	other threads:[~2011-02-13 22:07 UTC|newest]

Thread overview: 29+ 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
     [not found] ` <1264651770-sup-5197@ben-laptop>
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
     [not found]     ` <1b68c6791001272033q60dd31dbif4de285cd9bac83d-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2010-01-29  0:32       ` 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
     [not found]     ` <1292954195-20204-2-git-send-email-bgamari.foss@gmail.com>
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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=87bp2fwptx.fsf@gmail.com \
    --to=bgamari.foss@gmail.com \
    --cc=beagleboard@googlegroups.com \
    --cc=dbrownell@users.sourceforge.net \
    --cc=eric.miao@canonical.com \
    --cc=grant.likely@secretlab.ca \
    --cc=linux-omap@vger.kernel.org \
    --cc=michael.hennerich@analog.com \
    --cc=spi-devel-general@lists.sourceforge.net \
    --subject='Re: [PATCH] mcspi: Add support for GPIO chip select lines' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).