From mboxrd@z Thu Jan  1 00:00:00 1970
From: Stephen Warren <swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>
Subject: Re: Active low GPIOs (was [PATCH v1 1/4] i2c: mux: Add i2c-arbitrator
 'mux' driver)
Date: Thu, 14 Feb 2013 17:19:03 -0700
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To: Linus Walleij <linus.walleij-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
Cc: linux-doc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Daniel Kurtz <djkurtz-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>, Wolfram Sang <w.sang-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>, "linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" <linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, Lee Jones <lee.jones-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>, Guenter Roeck <guenter.roeck-IzeFyvvaP7pWk0Htik3J/w@public.gmane.org>, Stephen Warren <swarren-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>, Ben Dooks <ben.dooks-4yDnlxn2s6sWdaTGBSpHTA@public.gmane.org>, u.kleine-koenig-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org, Chris Ball <cjb-2X9k7bc8m7Mdnm+yROfE0A@public.gmane.org>, Grant Grundler <grundler-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>, devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org, Rob Herring <rob.herring-bsGFqQB8/DxBDgjK7y7TUQ@public.gmane.org>, Jean Delvare <khali-PUYAD+kWke1g9hUCZPvPmw@public.gmane.org>, Alexandre Courbot <acourbot-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>, "Ben Dooks (embedded platforms)" <ben-linux-elnMNo+KYs3YtjvyW6yDsg@public.gmane.org>, Girish Shivananjappa <girish.shivananjappa-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>, "bhushan.r" <bhushan.r-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>, Naveen Krishna Chatradhi <ch.naveen-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>, "sreekumar.c" <sreekumar.c-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>, Mark Brown <broonie-yzvPICuk2AATkU/dhu1WVueM+bqZidxxQQ4Iyu8u01E@public.gmane.org>, linux-kernel-u79uwXL29Tb/PtFMR13I2A@public.gmane.org
List-Id: linux-i2c@vger.kernel.org

On 02/14/2013 05:02 PM, Linus Walleij wrote:
> On Thu, Feb 14, 2013 at 6:05 PM, Doug Anderson <dianders-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org> wrote:
...
>>  One argument for keeping "cd-inverted" too is
>> for controllers that don't use a GPIO for card detect.
>>  In this case
>> you could imagine a MMC controller that has a "card detect" on
>> special-purpose pin and accessible via a status register.
> 
> This is actually the case with Integrator/CP and Versatile/AB.

In this case, I assume that the driver for the HW has custom code to
read the MMC controller's CD register bit, and hence it knows whether
the HW inverts it, and hence we don't need a property in DT to say so;
the driver will simply read the bit, invert it, and return it all
transparently? After all, the inversion isn't board-specific but IP
block specific.