From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (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 A764318BC19; Wed, 4 Dec 2024 13:08:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733317697; cv=none; b=fjE36QlpKwouZpUeLDuNzqse59vgVLAPYukOi3490uJurixvBypcTlumKzux9UzW7ojNZBVAditoxQyVcz9lOH6styYvTtcG2+TgkvPdU6e5opdqRKEy2nt+AoCGlQ5g5h2ylsnjOt4H6s4grUXy9mvR9G/NXZdtirroK0HAY+M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733317697; c=relaxed/simple; bh=05RaxY8NTJZsdAMk/F+MVGS6iIIbXrpDd0cv9NTMgsY=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=UJ3bQja8mgGjFoymL7ol43LRxJOOCoEFHdTmKsDSn+CNNllZ9oETBl2IzfDLww1J3Fnr+c+yu6IFDQ4R4ITe3DYENjGIDpZ5lzST4xL/zA/dATBX8xKq7IzOdioW3orXgdx3ws7H8nT4qz1lVdL6dSi3vq0QR8wFPHngmqOVAv8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=zFBy1gyA; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=6OVT3qJb; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="zFBy1gyA"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="6OVT3qJb" From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1733317692; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=ai6Td+7Re4FB0bJzl00OhDz0NYYlW8jViszOUHsn54c=; b=zFBy1gyAVOA9KgJwUcsOSY5q9TPYuTqu9LkGJXJC+RsJzCZ7aB9Hb8nslQDzhJxP91iwvv ayQxv7NwBnF4sH3k8udsY2kj2yVSgy3UbvHYSc/TlBtYprapRncVYqnz9OqkYwl7zoVdus WVNuh76NkV+R/LL6iczxXh3IyHhtj0znSpYq9EbcK+ddnOKFWaTbrCsVYKnVMMnzg2emje dBeADw1CwksN/+R6mi+nyuwA7ICGcwnyCynmBocoNktqzyxhYZzFPMvUeKhlH4+dnC4qMq SUHNdv4ZcG9KgMYfwso3Qa6O9aY8H93m3bWyRh3fQD81s5p3OtIIM+uCzLNuPQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1733317692; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=ai6Td+7Re4FB0bJzl00OhDz0NYYlW8jViszOUHsn54c=; b=6OVT3qJb7QSbzkewvzZYWWbqCQIHPBJ/jiRUicmS4fVMvTkHZhy9KpkcqF9yl8uB0Mg8Yi pXiq6/VkKOtt1zCA== To: Frank Li Cc: Manivannan Sadhasivam , Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= , Kishon Vijay Abraham I , Bjorn Helgaas , Arnd Bergmann , Greg Kroah-Hartman , "Rafael J. Wysocki" , Anup Patel , linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, imx@lists.linux.dev, Niklas Cassel , dlemoal@kernel.org, maz@kernel.org, jdmason@kudzu.us Subject: Re: [PATCH v9 2/6] PCI: endpoint: Add RC-to-EP doorbell support using platform MSI controller In-Reply-To: References: <20241203-ep-msi-v9-0-a60dbc3f15dd@nxp.com> <20241203-ep-msi-v9-2-a60dbc3f15dd@nxp.com> <87v7w0s9a8.ffs@tglx> Date: Wed, 04 Dec 2024 14:08:12 +0100 Message-ID: <87jzcfsiir.ffs@tglx> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain On Tue, Dec 03 2024 at 18:24, Frank Li wrote: > On Tue, Dec 03, 2024 at 11:15:27PM +0100, Thomas Gleixner wrote: >> The fact that a MSI parent domain supports DOMAIN_BUS_DEVICE_MSI does >> not guarantee that the parent is translation table based. >> >> As this is intended to be a generic library for all sorts of EP >> implementations, there needs to be >> >> - either a mechanism to prevent the initialization if the underlying >> MSI parent domain does not provide immutable messages > > How to know such information? It obviously needs to be flagged somehow in the domain and the EP magic needs to check that flag. >> >> - or support for endpoint specific msi_write_msg() implementations > > Even provide specific msi_write_msg(), write to address/data to shared > memory. > > host driver: > 1. read address/data from shared memory > 2. write data to address. > > 1 and 2 is not atomic. So it can't avoid above raise conditon. Correct. So you cannot support that case, which in turn requires to have a mechanism to check for the immutable property. Thanks, tglx