From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753968Ab2DWH2p (ORCPT ); Mon, 23 Apr 2012 03:28:45 -0400 Received: from metis.ext.pengutronix.de ([92.198.50.35]:48346 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753684Ab2DWH2o (ORCPT ); Mon, 23 Apr 2012 03:28:44 -0400 Date: Mon, 23 Apr 2012 09:28:39 +0200 From: Wolfram Sang To: Andrew Morton Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Arnd Bergmann , Shawn Guo , Huang Shijie Subject: Re: [PATCH V2 1/3] lib: add support for stmp-style devices Message-ID: <20120423072839.GC4568@pengutronix.de> References: <1332368519-22660-1-git-send-email-w.sang@pengutronix.de> <1332368519-22660-2-git-send-email-w.sang@pengutronix.de> <20120422235506.d3377f0e.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="w7PDEPdKQumQfZlR" Content-Disposition: inline In-Reply-To: <20120422235506.d3377f0e.akpm@linux-foundation.org> User-Agent: Mutt/1.5.21 (2010-09-15) X-SA-Exim-Connect-IP: 2001:6f8:1178:2:21e:67ff:fe11:9c5c X-SA-Exim-Mail-From: wsa@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-kernel@vger.kernel.org Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --w7PDEPdKQumQfZlR Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Sun, Apr 22, 2012 at 11:55:06PM -0700, Andrew Morton wrote: > On Wed, 21 Mar 2012 23:21:57 +0100 Wolfram Sang w= rote: >=20 > > MX23/28 use IP cores which follow a register layout I have first seen on > > STMP3xxx SoCs. In this layout, every register actually has four u32: > >=20 > > 1.) to store a value directly > > 2.) a SET register where every 1-bit sets the corresponding bit, > > others are unaffected > > 3.) same with a CLR register > > 4.) same with a TOG (toggle) register > >=20 > > Also, the 2 MSBs in register 0 are always the same and can be used to r= eset > > the IP core. > >=20 > > All this is strictly speaking not mach-specific (but IP core specific) = and, > > thus, doesn't need to be in mach-mxs/include. At least, mx6 and mx50 al= so > > utilize IP cores following this stmp-style. So: > >=20 > > Introduce a stmp-style device, put the code and defines for that in a p= ublic > > place (lib/), and let drivers for stmp-style devices select that code. > > To avoid regressions and ease reviewing, the actual code is simply copi= ed from > > mach-mxs. It definately wants updates, but those need a seperate patch = series. > >=20 > > Voila, mach dependency gone, reusable code introduced. Note that I didn= 't > > remove the duplicated code from mach-mxs yet, first the drivers have to= be > > converted. > >=20 > > ... > > > > include/linux/stmp_device.h | 20 +++++++++++ > > lib/Kconfig | 3 ++ > > lib/Makefile | 2 + > > lib/stmp_device.c | 80 +++++++++++++++++++++++++++++++++++= ++++++++ >=20 > It's good that this is being presented as library code, rather than > being buried in some device-specific directory then copied and pasted > ten times. >=20 > But ./lib/ does seem rather a strange place for it. Perhaps we need a > drivers/lib/ or something. We can use ./lib/ for now - it can always > be moved later on. The first version had it in drivers/base/ but that also felt strange. I like drivers/lib/. Arnd, do you agree? Shall I resend? >=20 > > --- /dev/null > > +++ b/lib/stmp_device.c >=20 > The functions in this file look terribly racy on SMP, or even with > preemption or interrupts. What happens if two CPUs or threads run > stmp_reset_block() against the same device at the same time? >=20 > Perhaps the caller is supposed to prevent that, and the documentation > which isn't there forgot to mention it ;) The code needs even more cleanups, timeouts are terrible as well. But as mentioned above, this series only moves existing code to a central place. Improvements would be the next, seperate step. Regards, Wolfram --=20 Pengutronix e.K. | Wolfram Sang | Industrial Linux Solutions | http://www.pengutronix.de/ | --w7PDEPdKQumQfZlR Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iEYEARECAAYFAk+VBKcACgkQD27XaX1/VRvmQQCeOi616QJuSWw78koSOmgN3yUx xvQAoJsWagvjQ1lsq9DhBlKlPUjdveDv =S7Xl -----END PGP SIGNATURE----- --w7PDEPdKQumQfZlR-- From mboxrd@z Thu Jan 1 00:00:00 1970 From: w.sang@pengutronix.de (Wolfram Sang) Date: Mon, 23 Apr 2012 09:28:39 +0200 Subject: [PATCH V2 1/3] lib: add support for stmp-style devices In-Reply-To: <20120422235506.d3377f0e.akpm@linux-foundation.org> References: <1332368519-22660-1-git-send-email-w.sang@pengutronix.de> <1332368519-22660-2-git-send-email-w.sang@pengutronix.de> <20120422235506.d3377f0e.akpm@linux-foundation.org> Message-ID: <20120423072839.GC4568@pengutronix.de> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Sun, Apr 22, 2012 at 11:55:06PM -0700, Andrew Morton wrote: > On Wed, 21 Mar 2012 23:21:57 +0100 Wolfram Sang wrote: > > > MX23/28 use IP cores which follow a register layout I have first seen on > > STMP3xxx SoCs. In this layout, every register actually has four u32: > > > > 1.) to store a value directly > > 2.) a SET register where every 1-bit sets the corresponding bit, > > others are unaffected > > 3.) same with a CLR register > > 4.) same with a TOG (toggle) register > > > > Also, the 2 MSBs in register 0 are always the same and can be used to reset > > the IP core. > > > > All this is strictly speaking not mach-specific (but IP core specific) and, > > thus, doesn't need to be in mach-mxs/include. At least, mx6 and mx50 also > > utilize IP cores following this stmp-style. So: > > > > Introduce a stmp-style device, put the code and defines for that in a public > > place (lib/), and let drivers for stmp-style devices select that code. > > To avoid regressions and ease reviewing, the actual code is simply copied from > > mach-mxs. It definately wants updates, but those need a seperate patch series. > > > > Voila, mach dependency gone, reusable code introduced. Note that I didn't > > remove the duplicated code from mach-mxs yet, first the drivers have to be > > converted. > > > > ... > > > > include/linux/stmp_device.h | 20 +++++++++++ > > lib/Kconfig | 3 ++ > > lib/Makefile | 2 + > > lib/stmp_device.c | 80 +++++++++++++++++++++++++++++++++++++++++++ > > It's good that this is being presented as library code, rather than > being buried in some device-specific directory then copied and pasted > ten times. > > But ./lib/ does seem rather a strange place for it. Perhaps we need a > drivers/lib/ or something. We can use ./lib/ for now - it can always > be moved later on. The first version had it in drivers/base/ but that also felt strange. I like drivers/lib/. Arnd, do you agree? Shall I resend? > > > --- /dev/null > > +++ b/lib/stmp_device.c > > The functions in this file look terribly racy on SMP, or even with > preemption or interrupts. What happens if two CPUs or threads run > stmp_reset_block() against the same device at the same time? > > Perhaps the caller is supposed to prevent that, and the documentation > which isn't there forgot to mention it ;) The code needs even more cleanups, timeouts are terrible as well. But as mentioned above, this series only moves existing code to a central place. Improvements would be the next, seperate step. Regards, Wolfram -- Pengutronix e.K. | Wolfram Sang | Industrial Linux Solutions | http://www.pengutronix.de/ | -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 198 bytes Desc: Digital signature URL: