From mboxrd@z Thu Jan 1 00:00:00 1970 From: marek.vasut@gmail.com (Marek Vasut) Date: Fri, 30 Jul 2010 07:19:09 +0200 Subject: [PATCH 11/13] [ARM] pxa/balloon3: PCF857x GPIO expander and LEDs In-Reply-To: References: <1280373389-32475-1-git-send-email-marek.vasut@gmail.com> <201007300644.04710.marek.vasut@gmail.com> Message-ID: <201007300719.09789.marek.vasut@gmail.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Dne P? 30. ?ervence 2010 07:09:00 Eric Miao napsal(a): > On Fri, Jul 30, 2010 at 12:44 PM, Marek Vasut wrote: > > Dne ?t 29. ?ervence 2010 12:00:41 Wookey napsal(a): > >> +++ Marek Vasut [2010-07-29 05:16 +0200]: > >> > Add supported for PCF8574A GPIO expander and LEDs attached to it. > >> > >> This IO board is an add-on used in some ballon configurations, not > >> part of the core board. There needs to be some way of selecting this > >> support when the loon is used in this configuration. We have the > >> balloon_has() macro which is used for dealing with the different > >> builds of the board itself. Perhaps it should be extended to deal with > >> add-on board functionality too? > >> > >> More obvious is using the CONFIG system to just enable this if > >> CUED_IO_BOARD is configured. > > > > You can just disable the PCF driver if you want to save space. In case > > you won't have the CUED board connected, the driver will just fail to > > probe so it's ok I believe. > > > > The macro could be extended, but do we want such a weird stuff in kernel? > > (especially if the driver can simply fail to probe). > > Are we able to detect this expansion board at run-time and registers > i2c/led-gpio if present. The thing I'm worried more on space is the > gpio_leds will be registered there even without the expansion board, > but what if someone tries to read/write to those LED controls? They won't register because the GPIOs won't be there. > > >> Wookey > > > > _______________________________________________ > > linux-arm-kernel mailing list > > linux-arm-kernel at lists.infradead.org > > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel