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 gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id B5DE2C00A8F for ; Tue, 24 Oct 2023 07:36:20 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 0818710E2E4; Tue, 24 Oct 2023 07:36:20 +0000 (UTC) Received: from mail-lj1-x244.google.com (mail-lj1-x244.google.com [IPv6:2a00:1450:4864:20::244]) by gabe.freedesktop.org (Postfix) with ESMTPS id 810E410E2E4; Tue, 24 Oct 2023 07:36:18 +0000 (UTC) Received: by mail-lj1-x244.google.com with SMTP id 38308e7fff4ca-2c594196344so5650021fa.3; Tue, 24 Oct 2023 00:36:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1698132977; x=1698737777; darn=lists.freedesktop.org; h=mime-version:references:in-reply-to:message-id:subject:cc:to:from :date:from:to:cc:subject:date:message-id:reply-to; bh=vNXLRTQD2rhYpRLHS1vdxpMTD+M/1xXcTTodDZ8Gpi4=; b=YuqlukNL80Ytq38y3jcfFWSDlvyGLyDJtgDH4D6Yn8/d+KRZf0xtpSpdH4P5UXK6PP 9v6QG0QoEGyltGiOt3LW8T8yedRJlwZ7IwuemW3aBA/TO9Q9PZRyuadzX/1JKobqGqSQ t/pPd5nMFREz7vliUB9oSnAwCZJelFfzvx72lbj2rmduPGSIbLmwGY5kQW3Qq+WALRBW S8NJ+PWL1HfH8M/foNxIdysstVFPFZl+YcquoLJPyrcV1YvkhgTDiTYrYAnLRFT+IgFM 6sb59HtxwdiyYh5wuTWFb0a4TCn3A1rQqGHhoaotUo+niHjOginVwd7MagO0TGL+4XMS T6dA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1698132977; x=1698737777; h=mime-version:references:in-reply-to:message-id:subject:cc:to:from :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=vNXLRTQD2rhYpRLHS1vdxpMTD+M/1xXcTTodDZ8Gpi4=; b=nMIQWXjEqpeO1okg8VXPIE7nxHsj6Zs6hb6wfmhRV0V6xM/YywMWgIR1rzh08lhec1 m6Rpn8/k4FW8/YGotWMkAn/+g9xcxNjmc9CERhzgRdBDY1s64Ie1gnIF4lw4BFGVP4aR 8my/ox+xKW0trZ528MLq4Ng8/kXBUXyvXo9xIBa/DNJeO0EG0jjnH/U0Uh5uzjf2lmNP 7VqvtFAnjWz+p3SQuxYWPvGejcFrFnL/qTLEBgQVOKJ7xJrdBoyv1TiclWGSQfLIm6aK 7g+PeGIVOs0CuyQCpVmV/82QUG02UgGJ55y97RBE+3soy1IJaBpPxLRXEVKmF/7hKu/k 6JPg== X-Gm-Message-State: AOJu0YwsBUvlBVMZxEuPOM96dIImxWm5Ip6EWx+YvxIJjjHGyAXjrSzA NXDT3yV0EL1SKGUNkAhaUqg= X-Google-Smtp-Source: AGHT+IHdmQv8NUYkJyvMm9UscwHe4urgCazEpqMtGpDUBUdb+3FOmJOQdgf921jh0Z9c/zw7Sntcwg== X-Received: by 2002:a2e:bea3:0:b0:2c5:d52:a08e with SMTP id a35-20020a2ebea3000000b002c50d52a08emr9625574ljr.20.1698132976246; Tue, 24 Oct 2023 00:36:16 -0700 (PDT) Received: from eldfell ([194.136.85.206]) by smtp.gmail.com with ESMTPSA id z24-20020a2e8858000000b002b9e9a8532dsm1936004ljj.138.2023.10.24.00.36.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 24 Oct 2023 00:36:15 -0700 (PDT) Date: Tue, 24 Oct 2023 10:36:04 +0300 From: Pekka Paalanen To: Simon Ser Subject: Re: [PATCH] drm/doc: describe PATH format for DP MST Message-ID: <20231024103604.6dd7f6d5@eldfell> In-Reply-To: <20231023203629.198109-1-contact@emersion.fr> References: <20231023203629.198109-1-contact@emersion.fr> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: multipart/signed; boundary="Sig_/qoRgGo0IEGzaEm2..UeouYJ"; protocol="application/pgp-signature"; micalg=pgp-sha256 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Dmitry Baryshkov , Daniel Vetter , dri-devel@lists.freedesktop.org, wayland-devel@lists.freedesktop.org Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" --Sig_/qoRgGo0IEGzaEm2..UeouYJ Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable On Mon, 23 Oct 2023 20:36:39 +0000 Simon Ser wrote: > This is already uAPI, xserver parses it. It's useful to document > since user-space might want to lookup the parent connector. >=20 > Additionally, people (me included) have misunderstood the PATH > property for being stable across reboots, but since a KMS object > ID is baked in there that's not the case. So PATH shouldn't be > used as-is in config files and such. >=20 > Signed-off-by: Simon Ser > Cc: Pekka Paalanen > Cc: Dmitry Baryshkov > Cc: Daniel Vetter > --- > drivers/gpu/drm/drm_connector.c | 5 +++++ > 1 file changed, 5 insertions(+) >=20 > diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connec= tor.c > index c3725086f413..392bec1355a3 100644 > --- a/drivers/gpu/drm/drm_connector.c > +++ b/drivers/gpu/drm/drm_connector.c > @@ -1198,6 +1198,11 @@ static const u32 dp_colorspaces =3D > * drm_connector_set_path_property(), in the case of DP MST with the > * path property the MST manager created. Userspace cannot change this > * property. > + * > + * In the case of DP MST, the property has the format > + * ``mst:-`` where ```` is the KMS object ID of = the > + * parent connector and ```` is a hyphen-separated list of DP MST > + * port numbers. Note, KMS object IDs are not stable across reboots. > * TILE: > * Connector tile group property to indicate how a set of DRM connector > * compose together into one logical screen. This is used by both high-= res Acked-by: Pekka Paalanen with or without the suggested "guaranteed" wording. Are DP MST port numbers guaranteed to be tied to the physical hardware configuration (e.g. how cables are connected) and therefore stable across reboots? What about stable across kernel upgrades? If I knew that, I could perhaps manufacture a stable identifier in userspace by replacing the parent connector ID with a stable connector designator. 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