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=-13.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 84CA6C47089 for ; Wed, 26 May 2021 14:24:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 61983613F4 for ; Wed, 26 May 2021 14:24:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234681AbhEZOZh (ORCPT ); Wed, 26 May 2021 10:25:37 -0400 Received: from relay8-d.mail.gandi.net ([217.70.183.201]:37501 "EHLO relay8-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233883AbhEZOZh (ORCPT ); Wed, 26 May 2021 10:25:37 -0400 Received: (Authenticated sender: paul.kocialkowski@bootlin.com) by relay8-d.mail.gandi.net (Postfix) with ESMTPSA id 743A61BF210; Wed, 26 May 2021 14:24:00 +0000 (UTC) Date: Wed, 26 May 2021 16:24:00 +0200 From: Paul Kocialkowski To: linux-media@vger.kernel.org, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, devel@driverdev.osuosl.org, linux-sunxi@googlegroups.com Cc: Yong Deng , Mauro Carvalho Chehab , Rob Herring , Maxime Ripard , Chen-Yu Tsai , Jernej Skrabec , Jonathan Corbet , Kishon Vijay Abraham I , Vinod Koul , Helen Koike , Dafna Hirschfeld , Greg Kroah-Hartman , Philipp Zabel , Sakari Ailus , Hans Verkuil , Thomas Petazzoni , kevin.lhopital@hotmail.com, Ezequiel Garcia , Laurent Pinchart Subject: Re: [PATCH v5 02/16] phy: Distinguish between Rx and Tx for MIPI D-PHY with submodes Message-ID: References: <20210115200141.1397785-1-paul.kocialkowski@bootlin.com> <20210115200141.1397785-3-paul.kocialkowski@bootlin.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="7zgmf44zur7folx5" Content-Disposition: inline In-Reply-To: <20210115200141.1397785-3-paul.kocialkowski@bootlin.com> Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org --7zgmf44zur7folx5 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi everyone, On Fri 15 Jan 21, 21:01, Paul Kocialkowski wrote: > As some D-PHY controllers support both Rx and Tx mode, we need a way for > users to explicitly request one or the other. For instance, Rx mode can > be used along with MIPI CSI-2 while Tx mode can be used with MIPI DSI. >=20 > Introduce new MIPI D-PHY PHY submodes to use with PHY_MODE_MIPI_DPHY. > The default (zero value) is kept to Tx so only the rkisp1 driver, which > uses D-PHY in Rx mode, needs to be adapted. I think it was Laurent who brought up on IRC that using a submode is probab= ly not a correct way to distinguish between Rx and Tx modes. Thinking about it again, it feels like selecting the direction at run-time would only be relevant if there's D-PHY hardware than can do both Tx and Rx *and* that can be muxed to either a MIPI DSI and a CSI-2 controller at run-time. For the Allwinner case, the D-PHY is the same hardware for both but there w= ill be one instance attached to each controller, not a single shared instance. It feels rather unlikely that a device with both MIPI DSI and CSI-2 would o= nly have one PHY for the two as this wouldn't allow concurrent use of the two controllers. Even in a case where there'd be n controllers and m < n bi-directional PHYs, it feels safe to assume that a static attribution would be sufficient. =20 As a result it feels more relevant to have this distinction in device-tree rather than via the PHY API. What do you think? Any suggestion on how this should be represented in device-tree? Cheers, Paul > Signed-off-by: Paul Kocialkowski > Acked-by: Helen Koike > --- > drivers/media/platform/rockchip/rkisp1/rkisp1-isp.c | 3 ++- > include/linux/phy/phy-mipi-dphy.h | 13 +++++++++++++ > 2 files changed, 15 insertions(+), 1 deletion(-) >=20 > diff --git a/drivers/media/platform/rockchip/rkisp1/rkisp1-isp.c b/driver= s/media/platform/rockchip/rkisp1/rkisp1-isp.c > index 2e5b57e3aedc..cab261644102 100644 > --- a/drivers/media/platform/rockchip/rkisp1/rkisp1-isp.c > +++ b/drivers/media/platform/rockchip/rkisp1/rkisp1-isp.c > @@ -948,7 +948,8 @@ static int rkisp1_mipi_csi2_start(struct rkisp1_isp *= isp, > =20 > phy_mipi_dphy_get_default_config(pixel_clock, isp->sink_fmt->bus_width, > sensor->lanes, cfg); > - phy_set_mode(sensor->dphy, PHY_MODE_MIPI_DPHY); > + phy_set_mode_ext(cdev->dphy, PHY_MODE_MIPI_DPHY, > + PHY_MIPI_DPHY_SUBMODE_RX); > phy_configure(sensor->dphy, &opts); > phy_power_on(sensor->dphy); > =20 > diff --git a/include/linux/phy/phy-mipi-dphy.h b/include/linux/phy/phy-mi= pi-dphy.h > index a877ffee845d..0f57ef46a8b5 100644 > --- a/include/linux/phy/phy-mipi-dphy.h > +++ b/include/linux/phy/phy-mipi-dphy.h > @@ -6,6 +6,19 @@ > #ifndef __PHY_MIPI_DPHY_H_ > #define __PHY_MIPI_DPHY_H_ > =20 > +/** > + * enum phy_mipi_dphy_submode - MIPI D-PHY sub-mode > + * > + * A MIPI D-PHY can be used to transmit or receive data. > + * Since some controllers can support both, the direction to enable is s= pecified > + * with the PHY sub-mode. Transmit is assumed by default with phy_set_mo= de. > + */ > + > +enum phy_mipi_dphy_submode { > + PHY_MIPI_DPHY_SUBMODE_TX =3D 0, > + PHY_MIPI_DPHY_SUBMODE_RX, > +}; > + > /** > * struct phy_configure_opts_mipi_dphy - MIPI D-PHY configuration set > * > --=20 > 2.30.0 >=20 --=20 Paul Kocialkowski, Bootlin Embedded Linux and kernel engineering https://bootlin.com --7zgmf44zur7folx5 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEJZpWjZeIetVBefti3cLmz3+fv9EFAmCuWgAACgkQ3cLmz3+f v9FhsAf+LCjDsXEPBS3IEa3r1GuNV4LBCN/X+lLIeNTjDh6K2INIlcpTAQKOFukJ SpuPbpbstXPTy9/vCtFP/DlZL1Oh2LO0HtXUlcb3rGEFO+1I4HUlOemAjl4TLbIv E0b9iFY1splxVIehgB1+IGh0+OeiFr/d5GegzOggbhxTN9Et1Ag43WAWglT86XcY MClLNUG8uVl86H83cFVP2AVzPj4GSmgiydKVcH8mLG6PE7DD3PfH5VzkDb2fAmMg uXJGP2qJCEXMAHwz6GFxEDArK22vzR7kzw3VAZWIwnBYP58QW/ifeL4D0Ak1aDbD wlmzQmgw2dpbHuESesA/00xaqumugA== =/RYX -----END PGP SIGNATURE----- --7zgmf44zur7folx5--