From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thierry Reding Subject: Re: [PATCH V3 02/19] memory: tegra: Add MC flush support Date: Fri, 17 Jul 2015 11:57:55 +0200 Message-ID: <20150717095754.GG3057@ulmo> References: <1436791197-32358-1-git-send-email-jonathanh@nvidia.com> <1436791197-32358-3-git-send-email-jonathanh@nvidia.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="hcut4fGOf7Kh6EdG" Return-path: Received: from mail-wi0-f180.google.com ([209.85.212.180]:38506 "EHLO mail-wi0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757252AbbGQJ6D (ORCPT ); Fri, 17 Jul 2015 05:58:03 -0400 Content-Disposition: inline In-Reply-To: <1436791197-32358-3-git-send-email-jonathanh@nvidia.com> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Jon Hunter Cc: Stephen Warren , Alexandre Courbot , Philipp Zabel , Peter De Schrijver , Prashant Gaikwad , Terje =?utf-8?Q?Bergstr=C3=B6m?= , Hans de Goede , Tejun Heo , Vince Hsu , "Rafael J. Wysocki" , Kevin Hilman , Ulf Hansson , linux-tegra@vger.kernel.org, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-pm@vger.kernel.org --hcut4fGOf7Kh6EdG Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Jul 13, 2015 at 01:39:40PM +0100, Jon Hunter wrote: > The Tegra memory controller implements a flush feature to flush pending > accesses and prevent further accesses from occurring. This feature is > used when powering down IP blocks to ensure the IP block is in a good > state. The flushes are organised by software groups and IP blocks are > assigned in hardware to the different software groups. Add helper > functions for requesting a handle to an MC flush for a given > software group and enabling/disabling the MC flush itself. >=20 > This is based upon a change by Vince Hsu . >=20 > Signed-off-by: Jon Hunter > --- > drivers/memory/tegra/mc.c | 110 ++++++++++++++++++++++++++++++++++++++++= ++++++ > drivers/memory/tegra/mc.h | 2 + > include/soc/tegra/mc.h | 34 ++++++++++++++ > 3 files changed, 146 insertions(+) Do we know if this is actually necessary? I remember having a discussion with Arnd Bergmann a while ago, and the Linux driver model kind of assumes that by the time a device is disabled all outstanding accesses will have stopped. Do we have a way to determine that this even makes a difference? Can we trigger a case where not doing this would cause breakage and see that adding this fixes that particular issue? Thierry --hcut4fGOf7Kh6EdG Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIcBAABCAAGBQJVqNGfAAoJEN0jrNd/PrOhfSIP/2GokJxt6q4xhScox9PHM2+H vX8uyfBHo4U3jx494uJ+AWvl0TORJ8/0J8PmLIbdi6TIeH5+cLG88qbaQslP6fpv rnxf+4Ci8Vnidd2jZ4+an2dP9u+EyDeXgf9P/fRmbHaeMJf6rvJRuDRIqcsQ5HnL 0mzjEDn3J5S9yZTKC0EQPX4vYuRzVMdVkh0GXEi3sAkH6IFDpBMde/or9jJyqOHO H4ulIIrLQBsoERbwabguASDcFPejmx68/6HwDY3m21BNy37OkTRW6DyCMki0x/Un lzJfIdrCo/QZMjn3vzR/eQBZjdJeCobzNkHmC3jm/Ed8cH2MlcBViqrE9Gmn+SGT IpSgxE7Cj468yt5erBctRz0aWVehtBirTPGWwJnUSnhYDgDVfAhS9kPqHucb/miA sNKqYCPm55ZqnYxXU7wwNITPYs4lUMgXvkl1shsmSIqxAA0z7DSrnbLZ3lukYlw1 LGxr7N6mLW9tCSes1cC7HyZ7bfTdxCDqVdfdLH1Q7QHrX0+mfnumSaUyjNEW9JTG G0w4l9O9Pgs/6eGyBAY+JQU+PH0Ogm579A1HSTg238CdkPZoDHat0SBYZKbh4PND eutu5UPrhNh1NzlO5zGRyUO+bV/DwE4THYkXBGVcDyvoe/5VJEPJEsDujGzQlCgW yG8aFjXm2sYu83htqlxj =4TS/ -----END PGP SIGNATURE----- --hcut4fGOf7Kh6EdG--