From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from m16.mail.126.com (m16.mail.126.com [220.197.31.8]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 099F982D75 for ; Fri, 23 Feb 2024 16:20:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=220.197.31.8 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708705258; cv=none; b=B/ml+xf2HuDLHlcxRCcZR313mBzQvs9ArxpNxMGmXhlHxNgn7NECQ63w7JfndXHQURD4djsaqrrlM2GslzjWL2BjjRDTj1dUZaZB3ahP6Mtdsn0GykwDrf8x01xk0BSA3LYDcC5LVVznkAwl4rFBxq9moJ3gyFS9uKbBouJjBPg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708705258; c=relaxed/simple; bh=L8PXCozSmgxbC1C2giikVCZGfkKTi2J80S0eCgayR/Q=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=e6Tof9EJEX8fsypzClR7CM+gLhnYwu3vRz5mqH0VB3Kbz9W6CP5IBJxXlD3/4fJv8k8615/EQyRKDUb88mMQk1OaKKY1CSU4AB0KuMbHvmzaQdZFuRbLJ6lrahEFW23Ophelszn5ap++e31BwDMZn/VKY9vvJRe+QD2FwLllazc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=126.com; spf=pass smtp.mailfrom=126.com; dkim=pass (1024-bit key) header.d=126.com header.i=@126.com header.b=EThzj3iT; arc=none smtp.client-ip=220.197.31.8 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=126.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=126.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=126.com header.i=@126.com header.b="EThzj3iT" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=126.com; s=s110527; h=From:Subject:Date:Message-Id:MIME-Version; bh=L8PXC ozSmgxbC1C2giikVCZGfkKTi2J80S0eCgayR/Q=; b=EThzj3iTuaiUOtJB7kd/o i9Qjfrapoy8rf5eFvnVaCWQE6J4y9L3wRh8iFhlgawV6uXTBYkCoX+ihn4LiY1NG KcVzhxlrWW0M8EB/8IFzvNsjJZ/ohFv22+9KweLj37GyAapmXmHCn1D2Vm9SPwbR K72ZSwkEbkwNEHBa9abQwk= Received: from nilq-virtual-machine.localdomain (unknown [60.24.208.202]) by gzga-smtp-mta-g1-0 (Coremail) with SMTP id _____wC3_ce6xdhlK7OlAw--.4841S2; Sat, 24 Feb 2024 00:20:12 +0800 (CST) From: "ni.liqiang" To: will@kernel.org, danielmentz@google.com Cc: iommu@lists.linux.dev, jin.qi@zte.com.cn, joro@8bytes.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, ni.liqiang@zte.com.cn, niliqiang.io@gmail.com, robin.murphy@arm.com Subject: Re: [PATCH] drivers/iommu: Ensure that the queue base address is successfully written during SMMU initialization. Date: Sat, 24 Feb 2024 00:20:10 +0800 Message-Id: <20240223162010.6884-1-ni_liqiang@126.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20240221160849.GB7362@willie-the-truck> References: <20240221160849.GB7362@willie-the-truck> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CM-TRANSID:_____wC3_ce6xdhlK7OlAw--.4841S2 X-Coremail-Antispam: 1Uf129KBjvdXoWrKw1UWryruw18XryDGw1xZrb_yoWfWwcE9F W7Gan7Jw4UXF4vkanI9Fs0vrs5A3y8ZFy8Ww4fKrsrKryfXFy0gry8Xry3t3W5Jay3XrZF 9a9rZ3WIy3ya9jkaLaAFLSUrUUUUjb8apTn2vfkv8UJUUUU8Yxn0WfASr-VFAUDa7-sFnT 9fnUUvcSsGvfC2KfnxnUUI43ZEXa7IUbJ3vUUUUUU== X-CM-SenderInfo: xqlbzxxtld0wa6rslhhfrp/1tbirxqJ5WVLZEeq5gADsb > (Disclaimer: I don't know what a CCG port is) CCG(CXL Gateway) is a part of the CMN700 Coherent Mesh Network. It plays a crucial role in facilitating cross-die access in a multi-chip system. > Hmmm. The part that doesn't make sense to me here is that migrating between > CPUs implies context-switching, and we have a DSB on that path in > __switch_to(). So why would adding barriers to the driver help? Maybe it > just changes the timing? This is very likely. Through our experiments, adding a delay before CMDQEN does not reproduce the failure of writing to the CMDQ base register. > I'm not sure what you're proposing, but I don't think Linux should be > changed to accomodate this. I am very grateful for the responses from both of you experts. We will continue to check the current hardware configuration of the system and attempt to fix this issue. Once again, I express my thanks. Thank you.