From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759333Ab2DZU1f (ORCPT ); Thu, 26 Apr 2012 16:27:35 -0400 Received: from na3sys009aog104.obsmtp.com ([74.125.149.73]:33525 "EHLO na3sys009aog104.obsmtp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758892Ab2DZU1d (ORCPT ); Thu, 26 Apr 2012 16:27:33 -0400 Date: Thu, 26 Apr 2012 23:26:14 +0300 From: Felipe Balbi To: Stephen Warren Cc: Hiroshi DOYU , swarren@nvidia.com, linux-tegra@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Felipe Balbi , 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: <20120426202610.GA30690@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> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="MGYHOYXEY6WxJCY8" Content-Disposition: inline In-Reply-To: <4F99A821.2040406@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 --MGYHOYXEY6WxJCY8 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi, 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. >=20 > > +#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 >=20 > That looks like a neat solution to avoid having a global device object. 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. > 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 SMMU > to defer its probe until the AHB driver has completed. >=20 > 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. Then, > after calling driver_for_each_device,: >=20 > if (!ahb_device_count) > return -EPROBE_DEFER > if (WARN_ON(ahb_device_count !=3D 1)) > return -EINVAL; > return 0; 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 balbi --MGYHOYXEY6WxJCY8 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iQIcBAEBAgAGBQJPma9iAAoJEIaOsuA1yqREG8IP/icfZHUq52y6dg7okc0f0FmQ lHKlp7pa4UL6fr8YG4UFI8m+az/CZ0uMb+P9vliXl/NNigTsuMnrcM+xXzWw86wb oLRx+8ShsU7PId0DsOVrpjEeeIdszn30KQTcngkLdNaX7I7fm99wfCPAUn7aSBuY qPffLzhm3yHMp8NE4eC559qjCfrp4rGiRBGVQWUMkN2hlGzNS1j7fiujT90aEeVM 0EIzB58qOX/UZIK2lszbo4x5qlWvQ+i4d/mB/ArypNJnnRVZUcoZc+mFe+R6tDz9 tWlWmxmlMLUDd1gMK6Tsr2JDrhcEQ5P1ER6stNmuVOQxeuoaEHDp63XUCYBalTMK 9jcE1ZiZ4gl5jZYrqIeRHj1XoTTZ5hxZxtQCHe1J5+LMA+S/2ImqGJvVutthjFFG oIHAmsHrYYttAAJdLIQ/5pjqCArio+mGXCkK8+bpUfN5kq4N53P4FgLcYf71szUa 9v5eYrGqCyptreVl16OssC+2B/LotUUZlGHnx0rTkwU8kdIGPSk9ytApP/baoFjB e8IGHXMx0a3sAwclFlGyBI3YB+CznDRReNKrcqjg4Hm58bGK2psu+7tcPbDC20SZ 2GvJWSVlfeWjLniKd9Anng47osxu50whSnCtu1eOF04vMTX91AIY2QCkf4vfvSO8 qlJbEZQvO6LN9gle+gdh =v3Kf -----END PGP SIGNATURE----- --MGYHOYXEY6WxJCY8--