From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759405Ab2DZUkK (ORCPT ); Thu, 26 Apr 2012 16:40:10 -0400 Received: from na3sys009aog136.obsmtp.com ([74.125.149.85]:51399 "EHLO na3sys009aog136.obsmtp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759222Ab2DZUkH (ORCPT ); Thu, 26 Apr 2012 16:40:07 -0400 Date: Thu, 26 Apr 2012 23:38:48 +0300 From: Felipe Balbi To: Stephen Warren Cc: balbi@ti.com, Hiroshi DOYU , swarren@nvidia.com, linux-tegra@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Colin Cross , Olof Johansson , Russell King , Tony Lindgren , H Hartley Sweeten , Jamie Iles , Rob Herring , linux-kernel@vger.kernel.org Subject: Re: [PATCHv3 2/4] ARM: tegra: Add SMMU enabler in AHB Message-ID: <20120426203847.GC30690@arwen.pp.htv.fi> Reply-To: balbi@ti.com References: <1335352072-4001-1-git-send-email-hdoyu@nvidia.com> <1335352072-4001-2-git-send-email-hdoyu@nvidia.com> <4F99A821.2040406@wwwdotorg.org> <20120426202610.GA30690@arwen.pp.htv.fi> <4F99B0F8.4040308@wwwdotorg.org> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="ZmUaFz6apKcXQszQ" Content-Disposition: inline In-Reply-To: <4F99B0F8.4040308@wwwdotorg.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --ZmUaFz6apKcXQszQ Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi, On Thu, Apr 26, 2012 at 02:32:56PM -0600, Stephen Warren wrote: > On 04/26/2012 02:26 PM, Felipe Balbi wrote: > > Hi, > >=20 > > On Thu, Apr 26, 2012 at 01:55:13PM -0600, Stephen Warren wrote: > >> On 04/25/2012 05:07 AM, Hiroshi DOYU wrote: > >>> Add extern func, "tegra_ahb_enable_smmu()" to inform AHB that SMMU is > >>> ready. > >> > >>> +#ifdef CONFIG_ARCH_TEGRA_3x_SOC > >>> +static int __tegra_ahb_enable_smmu(struct device *dev, void *data) > >> ... > >>> +int tegra_ahb_enable_smmu(void) > >>> +{ > >>> + return driver_for_each_device(&tegra_ahb_driver.driver, NULL, NULL, > >>> + __tegra_ahb_enable_smmu); > >>> +} > >>> +EXPORT_SYMBOL(tegra_ahb_enable_smmu); > >>> +#endif > >> > >> That looks like a neat solution to avoid having a global device object. > >=20 > > except that it won't work always. If you happen to have two AHB bridges, > > each using a separate smmu but only one smmu is ready, this will set > > SMMU_INIT_DONE on both bridges. >=20 > There is only 1. that's why there's a "if you happen to have" statement. If you stick to this "there is only 1" argument, why do you even make this into a platform driver ? Just stick the entire code hidden on the machine_init() code. Drivers a supposed to be able to instantiated multiple times and always work, this method won't work if tegra99999 ends up with two AHB bridges/SMMUs > >> However, if that driver_for_each_device finds no devices, the function > >> still succeeds. That doesn't seem right, and doesn't allow e.g. the SM= MU > >> to defer its probe until the AHB driver has completed. > >> > >> Perhaps add a local int variable to tegra_ahb_enable_smmu(), pass the > >> address to __tegra_ahb_enable_smmu, and have it increment the int. The= n, > >> after calling driver_for_each_device,: > >> > >> if (!ahb_device_count) > >> return -EPROBE_DEFER > >> if (WARN_ON(ahb_device_count !=3D 1)) > >> return -EINVAL; > >> return 0; > >=20 > > that would look, well, weird. Why don't you just different initcall > > leves for this ? Maybe smmu goes into postcore_initcall() and tegra_ahb > > goes into postcore_initcall_sync() ?? then you know that SMMU will be > > ready by the time you call tegra_ahb probe. Well, unless smmu's probe > > fail, but then again, IIUC it won't work anyway... >=20 > Uggh. I'd rather all these devices just got instantiated from device > tree and relied on deferred probe to manage any ordering, rather than > playing complex games with multiple initcall levels (and in the end > probably having to invent more and more initcall levels to correctly > represent all the dependencies). then do that... it'll be better than current trickery with driver_for_each_device() and my initcall trickery ;-) --=20 balbi --ZmUaFz6apKcXQszQ Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iQIcBAEBAgAGBQJPmbJXAAoJEIaOsuA1yqREPP4P/1i+vnYhVRr3u9C7Jq/c653V yO9oxIC3/DTwcLe7uLzBs1SrVQFLn8vc9KC6lLV8C8JZkDEM74w6+8e21hAiYytR j1F0A1zTBcAChGivFO4wCXUwcyQxOsTx4Bpjh6B7PQhOt/qYr9zBQs8/AFo0eYYa qJVTENZCr4bD2h21zlKtZcfSOoTAAdOcKW5UJL2L5vpYy/58NEGjWZzO3Ok1WCh3 CpL0AgsVLuoYO8uqxgacyWS8EChwlDK54jKu+0x8KUayWsCWlzNUz+6QxufgdgcB iScZp0o6Bew/QkYvT+n8QekaHuHQ8FJ5gZOPG7SaoFv88PdH0L1VBw/3hGZCnveh o4dLl1zNAqtICFI2RU/hATu3jf6a9LlNCRhhtWgJmeoShD1zum1wqJR3d85Xvmbe ry+FvyZc7ZXH2UFOb9MGTWIA5wklRMxEv4G8zMIqbQ1FZ4R1rgKx3aCQZmD1I8um KtNprat8SFbCtTaJVhqanSY+6NxeDZSH9n9bGiueC0GhrWuQoJ4iDlJdVw1CPUR7 gYzz9S8qq558jUclWIiV/JRw03Jm0rPrCvJsH7Dn+L0bPMbW2Xt/1dE+JgYboyX9 1o7/j4XS7MsIJHJ04YEbZp2XER356m2qy1ic7qNQyQVZ5gqOgyl6vdzn86SzSS+D ETkcN3bzBxoctjOuCJX8 =96kl -----END PGP SIGNATURE----- --ZmUaFz6apKcXQszQ--