Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751662AbeAEMFO (ORCPT + 1 other); Fri, 5 Jan 2018 07:05:14 -0500 Received: from heliosphere.sirena.org.uk ([172.104.155.198]:33218 "EHLO heliosphere.sirena.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751002AbeAEMFM (ORCPT ); Fri, 5 Jan 2018 07:05:12 -0500 Date: Fri, 5 Jan 2018 12:04:55 +0000 From: Mark Brown To: Arnaud Pouliquen Cc: Matthias Kaehlcke , Liam Girdwood , Jaroslav Kysela , Takashi Iwai , Rob Herring , Mark Rutland , "alsa-devel@alsa-project.org" , "devicetree@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Bhumika Goyal , huang lin , Brian Norris , Dylan Reid Subject: Re: [PATCH] ASoC: codecs: dmic: Use channel map for configs with a single mic Message-ID: <20180105120455.GA9076@sirena.org.uk> References: <20180104194848.198941-1-mka@chromium.org> <20180104195438.GA200397@google.com> <295ce358-c00e-74ce-50c1-1df32c2c6cf7@st.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="HcAYCG3uE/tztfnV" Content-Disposition: inline In-Reply-To: <295ce358-c00e-74ce-50c1-1df32c2c6cf7@st.com> X-Cookie: Prunes give you a run for your money. User-Agent: Mutt/1.9.2 (2017-12-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: --HcAYCG3uE/tztfnV Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, Jan 05, 2018 at 11:45:43AM +0100, Arnaud Pouliquen wrote: > >> +=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 num-channels =3D <1>; > In your implementation seems not linked to hardware but software... > DMIC driver description specifies the channels_max to 8 channels. > I suppose that it is used for DMIC codecs that integrate filters and are > connected to CPU DAI with I2S/PCM links. But it can be also used for > DMIC connected to CPU DAI with a SPI link (in this case decimation > filter in on Soc side). The intention with the DMIC CODEC is that it's used when the CPU directly has PDM inputs and the DMICs are just directly wired to it (stereo is obviously the norm here but some SoCs may bunch things up further for use with mic arrays). > If we continue to support both use cases, specify the number of channels > seems reasonable but this should be use to change the max channel > constraint, not to declare a control. Yes, that would seem the most obvious thing - it's how we handle things like CPU DAIs that support very high channel counts when connected to stereo CODECs for example. It's not obvious why we'd use a channel map here instead. --HcAYCG3uE/tztfnV Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAlpPaeYACgkQJNaLcl1U h9CoNwf+M4j9vaeXo+/z58OdIMwap1oV2G2/VqOsynaNnIt5CMYO4MCMeAkkwNfz OuWIrXi8iSOuKSjlqx/gf7YYnxXPR2ndxehOe7NS6a/Bjzmwis5eA5dBCDrF1S6p cQ8QTdQaIgq1KGAG6u276sb8TKDcL1MOkYYTTUHpky94lGbCBvJP4nxrMnMSG9LI q6XkdWVjKzCbuXwk05fXFB1W0Gwyz1VQRSmFYzC6CTDc3bgqT76TgrgtCBkoyKFx q7hFHzEE29Y53OFiiOFEE9DeY3ewIg4L4HVXOX4XotdAUCkNIe4srX/udEG+gPkl zJJvCoHag89oKEvTqoOUl27UA4VqRA== =MDpT -----END PGP SIGNATURE----- --HcAYCG3uE/tztfnV--