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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D4704E810B1 for ; Wed, 27 Sep 2023 09:22:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230442AbjI0JWU (ORCPT ); Wed, 27 Sep 2023 05:22:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48790 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230405AbjI0JV7 (ORCPT ); Wed, 27 Sep 2023 05:21:59 -0400 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7B4C4A3; Wed, 27 Sep 2023 02:21:58 -0700 (PDT) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 40E62C433D9; Wed, 27 Sep 2023 09:21:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1695806517; bh=I448svr5ZDYp4rTesI5QISMQCcJhofO8M8peXBBCVFM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=cpKxZGCHxET7gWuWcExH6CsMZ9pfGLXCTxYP/6YtBpQYujCM4n+xPTZfWZt+hhP0+ NXnwHc+pAdxCGnMaHqG/Fe0XfyZ7hnrvR9yUvw5WO7wnbI2+AAbR5mEarzdMpY4ZrU Q29GnboTaxtoij/admCVD36krYP8urbjTRMsMmGABzccsys3ZA/Ny0/47irocy/c1H kwy9x7vYNoO9GgSvezOMjMyX1J+5JH9ldG3965MD6GB6quP81N1kV3L5vIp+dYPh66 aRBHYrFHWg5mxLkDxWgfrWMMQpw32GaL4V4LoXSvjgjHS40bbRBm3cj0Mf5hKGUQu9 2N2HvVBwnyXrA== Date: Wed, 27 Sep 2023 11:21:54 +0200 From: Mark Brown To: Geert Uytterhoeven Cc: Fabrizio Castro , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Magnus Damm , linux-spi@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-renesas-soc@vger.kernel.org, Chris Paterson , Biju Das , Lad Prabhakar Subject: Re: [PATCH 1/2] spi: renesas,rzv2m-csi: Add SPI Slave related properties Message-ID: References: <20230926210818.197356-1-fabrizio.castro.jz@renesas.com> <20230926210818.197356-2-fabrizio.castro.jz@renesas.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="Pm+YXDPO8WF2t5nM" Content-Disposition: inline In-Reply-To: X-Cookie: Save energy: Drive a smaller shell. Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --Pm+YXDPO8WF2t5nM Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Sep 27, 2023 at 11:10:58AM +0200, Geert Uytterhoeven wrote: > On Wed, Sep 27, 2023 at 11:00=E2=80=AFAM Mark Brown = wrote: > > The description is clearly saying there is a chip select, _NO_CS seems > > entirely inappropriate. It's not specified in the device tree because > > when there's no chip select for a device it's a fundamental property of > > how the device is controlled and we don't need any information beyond > > the compatible. > In host mode, it indeed doesn't matter, as you can have only a single > device connected with SPI_NO_CS. > In device mode, the device needs to know if it must monitor the chip > select line or not. > In hindsight, I should have kept the question I had written initially, > but deleted after having read the documentation for the corresponding > RZ/V2M register bits: > What does it mean if this is false? That there is no chip select? > So "spi-no-cs" would be the inverse of "renesas,csi-ss". I see. Is there any control over what the chip select is when there is one, in which case we could just look to see if there's one specified? I'm a bit nervous about a generic property that maps onto _NO_CS since it's likely that people will start using that in device bindings when they shouldn't. --Pm+YXDPO8WF2t5nM Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAmUT9DIACgkQJNaLcl1U h9AoWgf8C4m4QGJxKqU2uTMR2OZGAiTjBvZPPRlWk3tOi86FMNdl2y3nyWSLo8Xn wX09m6jOWe9hdlXxeP865u3KMrDvVsHaL8wF8T7jNQc4h7LwGdE2PxsjvWEXS9qL 301JwbJPnR0u3DMoCfv6QzfDsJdw3BWhMgjYsA5fid0cnOjY1BENubwtg5egP5qB 0XbxeqK6/6GGtLIVl4IVobJaJbt76H5jKvXrqUNVskKQg+FfxA2yE6aWRoAcGbVn lQ09uL2W6G57XFRq9r4/R2y9AJWNgFeVmzpKsPSEiA/Yzd6RUHU/UN6mqAKNHgAi VUZMiQi/SpBI7EqDkS/x22F4sENSAw== =CrDz -----END PGP SIGNATURE----- --Pm+YXDPO8WF2t5nM--