From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DDB3AC31E40 for ; Mon, 12 Aug 2019 10:02:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AA2F72085A for ; Mon, 12 Aug 2019 10:02:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727669AbfHLKCf (ORCPT ); Mon, 12 Aug 2019 06:02:35 -0400 Received: from relay3-d.mail.gandi.net ([217.70.183.195]:35571 "EHLO relay3-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727447AbfHLKCf (ORCPT ); Mon, 12 Aug 2019 06:02:35 -0400 X-Originating-IP: 86.250.200.211 Received: from localhost (lfbn-1-17395-211.w86-250.abo.wanadoo.fr [86.250.200.211]) (Authenticated sender: maxime.ripard@bootlin.com) by relay3-d.mail.gandi.net (Postfix) with ESMTPSA id 0A47560008; Mon, 12 Aug 2019 10:02:31 +0000 (UTC) Date: Mon, 12 Aug 2019 12:02:31 +0200 From: Maxime Ripard To: Chen-Yu Tsai Cc: Jernej =?utf-8?Q?=C5=A0krabec?= , linux-sunxi , Code Kipper , Christopher Obbard , linux-arm-kernel , Liam Girdwood , Mark Brown , linux-kernel , Linux-ALSA , "Andrea Venturi (pers)" Subject: Re: [linux-sunxi] Re: [PATCH v4 6/9] ASoC: sun4i-i2s: Add multi-lane functionality Message-ID: <20190812100231.wlxitekfojr4jaki@flea> References: <20190603174735.21002-1-codekipper@gmail.com> <2092329.vleAuWJ0xl@jernej-laptop> <20190731122953.2u3iabd6gkn7jv7k@flea> <1589203.0AjJVEASy3@jernej-laptop> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="4tzqsccmfdz6gxrw" Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20180716 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --4tzqsccmfdz6gxrw Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Aug 06, 2019 at 02:22:13PM +0800, Chen-Yu Tsai wrote: > On Thu, Aug 1, 2019 at 1:32 PM Jernej =C5=A0krabec wrote: > > > > Dne sreda, 31. julij 2019 ob 14:29:53 CEST je Maxime Ripard napisal(a): > > > On Tue, Jul 30, 2019 at 07:57:10PM +0200, Jernej =C5=A0krabec wrote: > > > > Dne torek, 04. junij 2019 ob 11:38:44 CEST je Code Kipper napisal(a= ): > > > > > On Tue, 4 Jun 2019 at 11:02, Christopher Obbard > > wrote: > > > > > > On Tue, 4 Jun 2019 at 09:43, Code Kipper = wrote: > > > > > > > On Tue, 4 Jun 2019 at 09:58, Maxime Ripard > > > > > > > > > > > > > > > wrote: > > > > > > > > On Mon, Jun 03, 2019 at 07:47:32PM +0200, codekipper@gmail.= com > > wrote: > > > > > > > > > From: Marcus Cooper > > > > > > > > > > > > > > > > > > The i2s block supports multi-lane i2s output however this > > > > > > > > > functionality > > > > > > > > > is only possible in earlier SoCs where the pins are expos= ed and > > > > > > > > > for > > > > > > > > > the i2s block used for HDMI audio on the later SoCs. > > > > > > > > > > > > > > > > > > To enable this functionality, an optional property has be= en > > > > > > > > > added to > > > > > > > > > the bindings. > > > > > > > > > > > > > > > > > > Signed-off-by: Marcus Cooper > > > > > > > > > > > > > > > > I'd like to have Mark's input on this, but I'm really worri= ed > > > > > > > > about > > > > > > > > the interaction with the proper TDM support. > > > > > > > > > > > > > > > > Our fundamental issue is that the controller can have up to= 8 > > > > > > > > channels, but either on 4 lines (instead of 1), or 8 channe= ls on 1 > > > > > > > > (like proper TDM) (or any combination between the two, but = that > > > > > > > > should > > > > > > > > be pretty rare). > > > > > > > > > > > > > > I understand...maybe the TDM needs to be extended to support = this to > > > > > > > consider channel mapping and multiple transfer lines. I was t= hinking > > > > > > > about the later when someone was requesting support on IIRC a= while > > > > > > > ago, I thought masking might of been a solution. These can wa= it as > > > > > > > the > > > > > > > only consumer at the moment is LibreELEC and we can patch it = there. > > > > > > > > > > > > Hi Marcus, > > > > > > > > > > > > FWIW, the TI McASP driver has support for TDM & (i think?) mult= iple > > > > > > transfer lines which are called serializers. > > > > > > Maybe this can help with inspiration? > > > > > > see > > > > > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.= git/tre > > > > > > e/s > > > > > > ound/soc/ti/davinci-mcasp.c sample DTS: > > > > > > > > > > > > &mcasp0 { > > > > > > > > > > > > #sound-dai-cells =3D <0>; > > > > > > status =3D "okay"; > > > > > > pinctrl-names =3D "default"; > > > > > > pinctrl-0 =3D <&mcasp0_pins>; > > > > > > > > > > > > op-mode =3D <0>; > > > > > > tdm-slots =3D <8>; > > > > > > serial-dir =3D < > > > > > > > > > > > > 2 0 1 0 > > > > > > 0 0 0 0 > > > > > > 0 0 0 0 > > > > > > 0 0 0 0 > > > > > > > > > > > > > >; > > > > > > > > > > > > tx-num-evt =3D <1>; > > > > > > rx-num-evt =3D <1>; > > > > > > > > > > > > }; > > > > > > > > > > > > Cheers! > > > > > > > > > > Thanks, this looks good. > > > > > > > > I would really like to see this issue resolved, because HDMI audio = support > > > > in mainline Linux for those SoCs is long overdue. > > > > > > > > However, there is a possibility to still add HDMI audio suport (ste= reo > > > > only) even if this issue is not completely solved. If we agree that > > > > configuration of channels would be solved with additional property = as > > > > Christopher suggested, support for >2 channels can be left for a la= ter > > > > time when support for that property would be implemented. Currently, > > > > stereo HDMI audio support can be added with a few patches. > > > > > > > > I think all I2S cores are really the same, no matter if internally > > > > connected to HDMI controller or routed to pins, so it would make se= nse to > > > > use same compatible for all of them. It's just that those I2S cores= which > > > > are routed to pins can use only one lane and >2 channels can be use= d only > > > > in TDM mode of operation, if I understand this correctly. > > > > > > > > New property would have to be optional, so it's omission would resu= lt in > > > > same channel configuration as it is already present, to preserve > > > > compatibility with old device trees. And this mode is already suffi= cient > > > > for stereo HDMI audio support. > > > > > > Yeah, it looks like a good plan. > > > > > > > Side note: HDMI audio with current sun4i-i2s driver has a delay (ab= out a > > > > second), supposedly because DW HDMI controller automatically genera= tes CTS > > > > value based on I2S clock (auto CTS value generation is enabled per > > > > DesignWare recomendation for DW HDMI I2S interface). > > > > > > Is that a constant delay during the audio playback, or only at startu= p? > > > > I think it's just at startup, e.g. if you're watching movie, audio is i= n sync, > > it's just that first second or so is silent. > > > > > > > > > I2S driver from BSP Linux solves that by having I2S clock output > > > > enabled all the time. Should this be flagged with some additional > > > > property in DT? > > > > > > I'd say that if the codec has that requirement, then it should be > > > between the codec and the DAI, the DT doesn't really have anything to > > > do with this. > > > > Ok, but how to communicate that fact to I2S driver then? BSP driver sol= ves > > that by using different compatible, but as I said before, I2S cores are= not > > really different, so this seems wrong. > > Maybe we could make the DW-HDMI I2S driver require the I2S clock be on all > the time? You wouldn't need any changes to the DT. That's an option, but I'd really like to avoid it if possible. I guess we could also just add a delay in the powerup path in the HDMI case? Would it work? maxime -- Maxime Ripard, Bootlin Embedded Linux and Kernel engineering https://bootlin.com --4tzqsccmfdz6gxrw Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYIAB0WIQRcEzekXsqa64kGDp7j7w1vZxhRxQUCXVE5NwAKCRDj7w1vZxhR xaLkAP9Dau8CFZaqjfYlG8eEMwwmDGnmJ3Qb+OfrtRI9IxfL8AEA9pf3QqqQHWty 49bPYoHYZSaMSKd3MPMDdPL5aONO1Q8= =l/Kl -----END PGP SIGNATURE----- --4tzqsccmfdz6gxrw--