From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.10]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A172A1B4236; Mon, 9 Dec 2024 15:42:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.10 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733758939; cv=none; b=MxYKQ66yED0F5PYmfzWu87xjaYU1DNSjTlpmO7CVE+ulCTUJm++9xkFDA+83oDO8ev7v4kNt6MEbWROf45hwD02yVpII1mXXRrq4U8y4/C7w/dRS2zvapCAc+ltqiUbLwiMVsCwbiIDJeUVAFQ3Uzs2oKyirNDaGs1NywIYKO5k= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733758939; c=relaxed/simple; bh=P18b2PlB0MwGNJ/eQCw45a7as/FOYe1k97RGjVLARlg=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=as1zyWglSznPb4o50QKAHUrhCHwxN6hqOGtc/Lisjh8IIb2zfZLqFx7y5LxtgscgFsq4t1Re8DxCuJv4u3NyCjE/slwchoObocYiOaL5BwMeRRAYWAAiGZrrp9rYDmSJCBsos532cmjkul9SCYBEL++qGmO1osXQHTcsYGPraVY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=none smtp.mailfrom=linux.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=kDU4vQJe; arc=none smtp.client-ip=192.198.163.10 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="kDU4vQJe" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1733758938; x=1765294938; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=P18b2PlB0MwGNJ/eQCw45a7as/FOYe1k97RGjVLARlg=; b=kDU4vQJe5tdMQxjtWyK0WwIjSec5WgLrq1g7przjm9GTc8NuLYxlrt/u MoboT1M087pzk6arXUhDQiH7hcOUT5Ef7tsT8z2CBueG69W3zsgpR5yGI nlZsF+F5O1lnQEc5inTbvN+hPPnqYEmxA3QqW32mmPRraydb7TlyXb5uM SiQZ3E87UWdkMscnA2IQvkz/9CuCzGMRb0pOeXgp5X0VMYb4edamNrIKl q1WBFtdFM3cOiR2HztUEpYZhsdO+OlxO5vjT00EFk+QuQ/YWHYlgscHQJ Rn1S8jnsBrsfQ0AqUMGcoEoc3xjFWbJmnRwkDZwRElBtYn7gmQ5Ua2HV5 w==; X-CSE-ConnectionGUID: AO6ovWqXTqWMOYQbOHyaIQ== X-CSE-MsgGUID: 6lcw4Ev5Rqyd2VPF/oz4MQ== X-IronPort-AV: E=McAfee;i="6700,10204,11281"; a="45466889" X-IronPort-AV: E=Sophos;i="6.12,219,1728975600"; d="scan'208";a="45466889" Received: from fmviesa007.fm.intel.com ([10.60.135.147]) by fmvoesa104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 09 Dec 2024 07:42:17 -0800 X-CSE-ConnectionGUID: vBpVhrnzR9mGjzDWG200ag== X-CSE-MsgGUID: ifEavL7+SWa8OkyWYs+vYQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.12,219,1728975600"; d="scan'208";a="94954637" Received: from black.fi.intel.com ([10.237.72.28]) by fmviesa007.fm.intel.com with ESMTP; 09 Dec 2024 07:42:12 -0800 Received: by black.fi.intel.com (Postfix, from userid 1001) id 18D6644B; Mon, 09 Dec 2024 17:42:10 +0200 (EET) Date: Mon, 9 Dec 2024 17:42:10 +0200 From: Mika Westerberg To: Niklas Schnelle Cc: Ilpo =?utf-8?B?SsOkcnZpbmVu?= , Bjorn Helgaas , linux-pci@vger.kernel.org, Rob Herring , Krzysztof Wilczy??ski , "Maciej W . Rozycki" , Jonathan Cameron , Alexandru Gagniuc , Krishna chaitanya chundru , Srinivas Pandruvada , "Rafael J . Wysocki" , linux-pm@vger.kernel.org, Smita Koralahalli , linux-kernel@vger.kernel.org, Daniel Lezcano , Amit Kucheria , Zhang Rui , Christophe JAILLET , Lorenzo Pieralisi Subject: Re: [PATCH] PCI/portdrv: Disable bwctrl service if port is fixed at 2.5 GT/s Message-ID: <20241209154210.GL4955@black.fi.intel.com> References: <20241207-fix_bwctrl_thunderbolt-v1-1-b711f572a705@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20241207-fix_bwctrl_thunderbolt-v1-1-b711f572a705@kernel.org> On Sat, Dec 07, 2024 at 07:44:09PM +0100, Niklas Schnelle wrote: > Trying to enable bwctrl on a Thunderbolt port causes a boot hang on some > systems though the exact reason is not yet understood. As per the spec > Thunderbolt PCIe Downstream Ports have a fake Max Link Speed of 2.5 GT/s > (USB4 v2 sec 11.2.1): > > "Max Link Speed field in the Link Capabilities Register set to 0001b > (data rate of 2.5 GT/s only). > Note: These settings do not represent actual throughput. > Throughput is implementation specific and based on the USB4 Fabric > performance." > > More generally if 2.5 GT/s is the only supported link speed there is no > point in throtteling as this is already the lowest possible PCIe speed > so don't advertise the capability stopping bwctrl from being probed on > these ports. > > Link: https://lore.kernel.org/linux-pci/Z1R4VNwCOlh9Sg9n@wunner.de/ > Fixes: 665745f27487 ("PCI/bwctrl: Re-add BW notification portdrv as PCIe BW controller") > Tested-by: Niklas Schnelle > Signed-off-by: Niklas Schnelle Makes sense to me, Reviewed-by: Mika Westerberg