From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ej1-f52.google.com (mail-ej1-f52.google.com [209.85.218.52]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 92D6E30BB9E for ; Mon, 1 Dec 2025 12:26:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.218.52 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764591977; cv=none; b=GfSeJoLT9mRNt27B77rRGIIxzOr4ltQ8oLyeNS+l4aAsv49cEb0UxiwIKjFgY3UPKr+Z0Dn6WmWp/igW+tU89jz/mZIRotf3p6x21NzerLDh9hkLGU1UQoGqdoF9KjuZjlWqVvvXRCcWIySXp4OfwtxG0Da8ojmptubHzX5xR4U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764591977; c=relaxed/simple; bh=6OIAP4fGmgimdtTJrfs4TMLavclr4sycXrfjFbr+ixw=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=XEeVxXNRkyjlPt13KY69abhfzfaafNhHTPlPqLoI7T7aAF235MnRLbhntWuhMtccVu8IwUXMiecqX+BRobpcjaJW1GKgqM7cw6y/bALRrAdGCJ/wp+kUWPjJEdxkjKXpbkmrSgj1Bq0d5ZKrdIMpj8SgCiB7IaMoYNEzHfaH33U= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=chromium.org; spf=pass smtp.mailfrom=chromium.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b=NIX0hhER; arc=none smtp.client-ip=209.85.218.52 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=chromium.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=chromium.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="NIX0hhER" Received: by mail-ej1-f52.google.com with SMTP id a640c23a62f3a-b7355f6ef12so820920466b.3 for ; Mon, 01 Dec 2025 04:26:13 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; t=1764591972; x=1765196772; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=A+3pYB2i1GVS17Vzr4d6LX2uFwVFZUJ8kMPwOvWk9Mw=; b=NIX0hhERlOQ51sIn3vC1GtagNThSMatWMCuH9husFtKfHdm2B9cNtt/LAdbKNebSRD gUHT7jXKQhJ5LQTwJ+wVo+7Um5aqndE+U9V2/38F9I2+8obiptXIGGjDW8VMpHv6KKEY VBvSlsFwZvXZdVHUdxXBioFw9deMpqAffe7Gk= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1764591972; x=1765196772; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=A+3pYB2i1GVS17Vzr4d6LX2uFwVFZUJ8kMPwOvWk9Mw=; b=QOSjtgK0HY5EpkFXu6RSpg2daetzy3V0HY3pdemwgqqV/MW+17hr67nzv8uBQ/OyPx OP9+LsK486pIjpYlAIqwXPJJ4Kh0MuECjQehewRkheF5wcqSxZZbO84nYMLWFtWg2EPS 37ade9s1zKSZTfX0J9xO2mCX4WIO8JI8deDmNR0E7F86pbfVlTlAl66ZAkiH8S2yfu/O 65k/KK5R0MjUxVaQeWuYim3XvPgbG76eIUIv1Ox56AWP9OaAuqscoVZX6+5BAi34fs/H 14PV8gYkEak8+D6myJ2snpI+uUyfWLwSq5xoy8hCmwFSL4sJ78L4Y2FPE6X1MmBXZj3+ JzYw== X-Forwarded-Encrypted: i=1; AJvYcCUc1+5KhcGpCUvywDx7fwLhOK/ygpclCVEmXyuoEt4ea/CqdUoQqBY+OLqT1HFv8gKurqzlG5x5GZbVTGk=@vger.kernel.org X-Gm-Message-State: AOJu0YwaVYf2uFuMTP6uZC1J/XZC82tKyvzAMSmQqF0jcHYuHeWhw1Tg tMeswiy89ypJt0mh+L8x1bMAtFuDDxq9yXgvNZirGwVz5VboCQq3kzh+trFhfLOCug== X-Gm-Gg: ASbGncuyKCFEC74LrlDhCyBzEQH/lEBc9XSgsBEWU/rLHFII1+UXxr6x+xyoZwpJ/nH lAU5rUeKCN5DLjuPE4I8e5R7mRwQ0cCKA0Nxp+MrwRUJ1IOhUF9MRSCRes1jG9PuiTYkkB6mfzn 9hnHGhI+g0y1P+E3f8Tdk9iS/b7YpxbncnfgA3ZMBiMeEu/Fwgoc00Vk95KbTkrWRevTEv0b/lM PYuPQiPHxwigR7UQ+GLZkVBMK8Qqn9h22oVtOxrfZOJGqHOPsjPaH08n8kelbwDxPAqdlXrS1td BDg6camKKbKlq2vrenLt+71re1jHmDrRRckDHFcTKC5tPBRFEzAPMb6OK+WD00xSSSbFLUiuyr7 9evz2dEnhnc5z7H2zTekxy6WBR38qtFS9ql3/RjDM26r71fmD7BtB4fQfCfBEh3VRcydTeLRYtq VLXaUM7J9CGGiKqemFZT31coukPTgmPn5pMAb7sYNZEPcdE/Pqlf9Va4DlbUmCPxoP+Rj5S1CqE xvla0DtawfsiizJ2rqNPA== X-Google-Smtp-Source: AGHT+IGH2kXVtk/N3N/Dg3EeJbOt8u37moIvhcU7Nkm4tdM0wE9npVXQZ9y8vtxtXB3dn6B6XLUOYw== X-Received: by 2002:a17:906:c14b:b0:b73:398c:c595 with SMTP id a640c23a62f3a-b767156556amr4621926966b.19.1764591971716; Mon, 01 Dec 2025 04:26:11 -0800 (PST) Received: from akuchynski.c.googlers.com.com (218.127.147.34.bc.googleusercontent.com. [34.147.127.218]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-b76f519e331sm1229049266b.24.2025.12.01.04.26.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 01 Dec 2025 04:26:11 -0800 (PST) From: Andrei Kuchynski To: Heikki Krogerus , Abhishek Pandit-Subedi , Benson Leung , Jameson Thies , Tzung-Bi Shih , linux-usb@vger.kernel.org, chrome-platform@lists.linux.dev Cc: Guenter Roeck , Greg Kroah-Hartman , Dmitry Baryshkov , "Christian A. Ehrhardt" , Abel Vesa , Pooja Katiyar , Pavan Holla , Madhu M , Venkat Jayaraman , linux-kernel@vger.kernel.org, Andrei Kuchynski Subject: [PATCH RFC 0/8] USB Type-C alternate mode selection Date: Mon, 1 Dec 2025 12:25:56 +0000 Message-ID: <20251201122604.1268071-1-akuchynski@chromium.org> X-Mailer: git-send-email 2.52.0.158.g65b55ccf14-goog Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit This patch series introduces functionality to the USB Type-C Alternate Mode negotiation process by implementing a priority-based selection mechanism. Currently, DisplayPort and Thunderbolt drivers initiate a mode entry separately within their respective probe functions. The Power Delivery Controller (PDC) retains the ability to activate either USB4 mode or Alternate Modes based on its internal policy. The mode selection mechanism disables Alternate Modes to be entered by their respective drivers and the PDC. Instead, a priority-ordered approach is used to activate the most desirable mode. A new `priority` field is added to the `typec_altmode` structure to store a numerical priority value, with all priorities being unique. If the port driver supports the mode selection feature, it must set the `mode_selection` boolean field within the `typec_altmode` structure. This indicates to the alternate mode drivers that they are not to activate the altmode separately. The mode selection process is managed by three API functions: - `typec_mode_selection_start` - `typec_altmode_state_update` - `typec_mode_selection_delete` When a partner device is connected, the `typec_mode_selection_start` function executes the following steps: - It compiles a priority-ordered list of Alternate Modes that are mutually supported by both the port and the partner. - A dedicated mode selection task is subsequently initiated on the Work Queue. - This task attempts to activate a mode by starting with the highest-priority altmode on the list. Alternate modes are identified with their SVIDs. Activation/Deactivation performed via `activate` typec_altmode operation. The process stops as soon as a mode is successfully entered. Otherwise, after a timeout or if an error occurs, the next alternative mode will be activated. The `typec_altmode_state_update` function is invoked by the port driver to communicate the current mode of the Type-C connector. The `typec_mode_selection_delete` function is responsible for stopping the currently running mode selection process and releasing all associated system resources. USB4 activation can be handled in two distinct ways: - Treated like an Alternate Mode, using associated sysfs attributes - `activate` port attribute to enable/disable the mode, `activate` partner attribute to activate/deactivate the mode, `priority` to keep modes priority. - Like a separate USB mode representing in sysfs via `usb_capabily` ports attribute to enable the mode on the port and `usb_mode` partner attribute to activate the mode. In this scenario, USB4 is the highest-priority mode, without the need for a separate priority field. It is put on the top of the preferred list if it is supported by the partner (partner->usb_capability has USB_CAPABILITY_USB4 bit set) and is supported and enabled on the port (port->usb_mode is USB_MODE_USB4). This patch series implements the second approach. It identifies the USB4 mode via its SVID 0xFF00. Instead of using the typec_altmode_ops activate() function, activation is handled via the typec_operations enter_usb_mode() function. Mode selection is initiated only once during partner registration, and only if the port driver provides support for this feature. Subsequent mode-switching activities can be managed via existing sysfs entries. Any modifications to altmode priorities are relevant only to future connections. This series was tested on an Android OS device with kernel 6.17, PDC: TI TPS6699, Realtek RTS5453. This series depends on the 'USB Type-C alternate mode priorities' series: https://lore.kernel.org/all/20251124124639.1101335-1-akuchynski@chromium.org/ Andrei Kuchynski (8): usb: typec: Implement mode selection usb: typec: Integrate USB4 into the mode selection process usb: typec: Introduce mode_selection bit usb: typec: ucsi: Support mode selection to activate altmodes usb: typec: ucsi: Enforce mode selection for cros_ec_ucsi usb: typec: ucsi: Implement enter_usb_mode operation usb: typec: ucsi: Support for Thunderbolt alt mode platform/chrome: cros_ec_typec: Enforce priority-based mode selection drivers/platform/chrome/cros_ec_typec.c | 47 ++- drivers/platform/chrome/cros_typec_altmode.c | 8 +- drivers/usb/typec/Makefile | 2 +- drivers/usb/typec/altmodes/displayport.c | 6 +- drivers/usb/typec/altmodes/thunderbolt.c | 2 +- drivers/usb/typec/class.c | 1 + drivers/usb/typec/class.h | 2 + drivers/usb/typec/mode_selection.c | 308 +++++++++++++++++++ drivers/usb/typec/ucsi/Makefile | 4 + drivers/usb/typec/ucsi/cros_ec_ucsi.c | 44 +++ drivers/usb/typec/ucsi/thunderbolt.c | 199 ++++++++++++ drivers/usb/typec/ucsi/ucsi.c | 56 +++- drivers/usb/typec/ucsi/ucsi.h | 27 ++ include/linux/usb/typec.h | 1 + include/linux/usb/typec_altmode.h | 43 +++ 15 files changed, 728 insertions(+), 22 deletions(-) create mode 100644 drivers/usb/typec/mode_selection.c create mode 100644 drivers/usb/typec/ucsi/thunderbolt.c -- 2.52.0.158.g65b55ccf14-goog