From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754628AbbDHSyt (ORCPT ); Wed, 8 Apr 2015 14:54:49 -0400 Received: from mezzanine.sirena.org.uk ([106.187.55.193]:57339 "EHLO mezzanine.sirena.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751651AbbDHSyq (ORCPT ); Wed, 8 Apr 2015 14:54:46 -0400 Date: Wed, 8 Apr 2015 19:54:20 +0100 From: Mark Brown To: Lori Hikichi Cc: Scott Branden , Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , Liam Girdwood , Jaroslav Kysela , Takashi Iwai , alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, bcm-kernel-feedback-list@broadcom.com, Dmitry Torokhov , Anatol Pomazao , abrestic@google.com, bryeung@google.com, olofj@google.com, pwestin@google.com Message-ID: <20150408185420.GH6023@sirena.org.uk> References: <1427771784-29950-1-git-send-email-sbranden@broadcom.com> <20150331064338.GE2869@sirena.org.uk> <551EEAF8.7050108@broadcom.com> <20150406095803.GD6023@sirena.org.uk> <55249258.1020907@broadcom.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="spjIDaiUctnsA4Sg" Content-Disposition: inline In-Reply-To: <55249258.1020907@broadcom.com> X-Cookie: I've been there. User-Agent: Mutt/1.5.23 (2014-03-12) X-SA-Exim-Connect-IP: 94.175.94.161 X-SA-Exim-Mail-From: broonie@sirena.org.uk Subject: Re: [PATCH 0/2] Cygnus Audio Driver X-SA-Exim-Version: 4.2.1 (built Mon, 26 Dec 2011 16:24:06 +0000) X-SA-Exim-Scanned: Yes (on mezzanine.sirena.org.uk) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --spjIDaiUctnsA4Sg Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Tue, Apr 07, 2015 at 07:28:40PM -0700, Lori Hikichi wrote: > On 15-04-06 02:58 AM, Mark Brown wrote: > >OK, then it's going to need to be a clock provider at some point - the > >clock will be going into external devices which are going to need to be > >able to interact with the clock (for example, to get the rate). > Currently, the ASoC machine driver is responsible for requesting a certain > frequency of MCLK be generated from our driver and then also sending the > frequency information along to the external device (codec). > This is done via the snd_soc_dai_set_sysclk. That is the only clock > interaction we have needed for the core part of the driver. For enhanced I have some passing familiarity with ASoC... if you look at newer drivers, especially those for DT systems, you'll see that we're transitioning CODEC drivers to use the clock API for their clocks since this makes integrating with both generic ASoC things like simple card and non-ASoC clocks. > features, we also have the need to make minor adjustments (tweaks) to the > PLL. The tweaks are used to make the PLLs output frequency match as closely > as possible to a true reference frequency. As such, we would like to provide > the finest adjustment resolution as possible. The clocking framework only > seems to allow for a 1 Hz adjustment. This limitation and the fact that no > other device seems to need to interact directly will the PLL are why we have > not put it in the clocking framework. That's going to be an issue no matter where you put the control - the ASoC specific clocking APIs don't have any control here either. I don't know if we want to add the functionality for doing very fine grained adjustments into the clock API or not (the use cases seem limited though I'm sure they exist), though I do think we should have that discussion if only to confirm, but that's a separate thing to how we expose any userspace control - the clock API is a kernel internal thing. --spjIDaiUctnsA4Sg Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQEcBAEBCAAGBQJVJXlbAAoJECTWi3JdVIfQ5DEH/RgTLRb845J//cT/S581kgSu HxgncKuduAle5OzTGTr4EbWHdgD8nFUWWJIvV50ZgPScIq8eWeh7ll10HvIjIS7u HrdinKXttA70PbcZTIThzmj26vADLMPXhp78dJgKVQz7/x5ras7XHNQcGakVcFOY 9aOpjIkMIbH44yP056LIudPz2WhVHMNZFgbFVx+G9oeUM03M4HKJQT3jaQ1hlxVz 7z6655+JFMnSjKznI1wOlZsXBx+vmNZCteB4kdZKUwbwnm7GwVYk4X1kI5DdDm1x hrTwd4HEs/oqM9hUu2sLqSEgymjixeo5iig4kWtHuANikUvp7HUaEixdvoFTrPo= =op1M -----END PGP SIGNATURE----- --spjIDaiUctnsA4Sg--