Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759542AbXF3O3p (ORCPT ); Sat, 30 Jun 2007 10:29:45 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757579AbXF3O24 (ORCPT ); Sat, 30 Jun 2007 10:28:56 -0400 Received: from smtp117.sbc.mail.sp1.yahoo.com ([69.147.64.90]:47034 "HELO smtp117.sbc.mail.sp1.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1757446AbXF3O2y (ORCPT ); Sat, 30 Jun 2007 10:28:54 -0400 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=pacbell.net; h=Received:X-YMail-OSG:From:To:Subject:Date:User-Agent:Cc:References:In-Reply-To:MIME-Version:Content-Disposition:Message-Id:Content-Type:Content-Transfer-Encoding; b=vBimGTRAJZxFP0gRspyoU6nxM74hXUvLf+Vcv/7w1Ij7CfZfn3a0fXYdIKOhIqt0JFk1VBVUIqE983iIre8w1XFk4SfBbyjv00WFZq69JN31nkZCzFNotY1lwKRCAIO7DNx2c00GuK3CMsg7ICxMClhRjjcbdfmJFan//q/u1Wo= ; X-YMail-OSG: owvHzn4VM1kcnCClysdK4uzp8NuopFsVMkJFk9a4N2sxaHBh From: David Brownell To: linux-usb-devel@lists.sourceforge.net, Andrew Morton Subject: Re: [linux-usb-devel] [PATCH] PXA27x UDC driver. Date: Sat, 30 Jun 2007 07:28:48 -0700 User-Agent: KMail/1.9.6 Cc: Rodolfo Giometti , linux-kernel@vger.kernel.org, Yang-r58472 , linux-arm-kernel@lists.arm.linux.org.uk References: <20070628103619.GW13886@enneenne.com> <20070628141205.GA13886@enneenne.com> <20070628142949.02ca9eab.akpm@linux-foundation.org> In-Reply-To: <20070628142949.02ca9eab.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Disposition: inline Message-Id: <200706300728.48411.david-b@pacbell.net> Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1153 Lines: 27 On Thursday 28 June 2007, Andrew Morton wrote: > > +#undef DISABLE_TEST_MODE > > enabling DISABLE_TEST_MODE seens to enable test mode. Confused. Blame it on Intel. ISTR that early pxa2[156]x silicon had something called "test mode". And a boatload of errata, with a common thread in workarounds: using the "test mode" helped many things work better, although it was neither necessary nor sufficient. If one were to #define DISABLE_TEST_MODE, software could experiment with other workarounds ... and maybe be able to get the documented "double buffering" feature to work. Later silicon stopped documenting "test mode" as such, effectively making certain workarounds become the standard way to use the chip. Which doesn't explain why pxa270 code has pxa2[156]x devel hooks, but explains why pxa2[156]x code wants the hardware "test mode" to be enabled ... except during developer experiments. - Dave - 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/