Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933668AbZLOVHV (ORCPT ); Tue, 15 Dec 2009 16:07:21 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1760214AbZLOVHU (ORCPT ); Tue, 15 Dec 2009 16:07:20 -0500 Received: from 216-239-44-51.google.com ([216.239.44.51]:38225 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760194AbZLOVHS (ORCPT ); Tue, 15 Dec 2009 16:07:18 -0500 DomainKey-Signature: a=rsa-sha1; s=beta; d=google.com; c=nofws; q=dns; h=mime-version:in-reply-to:references:date:message-id:subject:from:to: cc:content-type:x-system-of-record; b=eEXgL42CNImggIcV+9U2FoTdhkyBIXjLpc/q55cNihPmxfcIK0yj0xew6NNnbFQe4 rs77MxR3ene8mjGgrSaLg== MIME-Version: 1.0 In-Reply-To: <20091215204803.GA26319@shareable.org> References: <4B1ECEEE.3000209@bluewatersys.com> <20091210172458.GJ19454@elf.ucw.cz> <4B2150B7.3040207@bluewatersys.com> <20091211221015.GB24456@elf.ucw.cz> <20091214064545.GK5114@elf.ucw.cz> <1260813293.13078.15.camel@c-dwalke-linux.qualcomm.com> <20091215204803.GA26319@shareable.org> Date: Tue, 15 Dec 2009 13:07:13 -0800 Message-ID: Subject: Re: GPIO support for HTC Dream From: Brian Swetland To: Jamie Lokier Cc: H Hartley Sweeten , Daniel Walker , Pavel Machek , Iliyan Malchev , "Arve Hj?nnev?g" , kernel list , Ryan Mallon , linux-arm-kernel Content-Type: text/plain; charset=UTF-8 X-System-Of-Record: true Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1023 Lines: 21 On Tue, Dec 15, 2009 at 12:48 PM, Jamie Lokier wrote: > > Perhaps the Dream's GPIOs are similar, but with opposite polarity. > If it also has the same transition driving spike, writing a 1->0 > transition would be bad for the hardware making the shadow variable > even more important. Arve will certainly step in if I'm wrong here, but I believe the issue is that the dream CPLD GPIOs (which is what we're talking about, not the MSM7K's onboard GPIOs which are more flexible) have no way to read the set output state back. So, you can't read-modify-write to change just one of the 8 bits in a given bank. The default mask values in the android msm tree's trout gpio board files are based on what he shipping HTC bootloader initializes things to. Brian -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/