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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E483AC433EF for ; Mon, 29 Nov 2021 18:23:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1354142AbhK2S02 (ORCPT ); Mon, 29 Nov 2021 13:26:28 -0500 Received: from sin.source.kernel.org ([145.40.73.55]:47278 "EHLO sin.source.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1348062AbhK2SYR (ORCPT ); Mon, 29 Nov 2021 13:24:17 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by sin.source.kernel.org (Postfix) with ESMTPS id C220ECE13D9; Mon, 29 Nov 2021 18:20:58 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6EE23C53FC7; Mon, 29 Nov 2021 18:20:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1638210057; bh=rF+rlf10wf5LoJqQVpm57G+ksL9EpmM1cpYegWZTn3A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=o7MmLYEzTj5eNKVHi1vHtl98nl5KvcJp8uapeOP9HkKat/EfyUoXLxAFEp1qcbXoC OP7tY9o4yJ2Cj+SiAZz0ggBq3P7240AoNOBe3wxq5K+Ika6WB1mLsY5VAh+TqWAlTo vOMGVWCgcITPjezSuLLgTaJ2PMQzdb8Bge0Ct60g= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, =?UTF-8?q?Pali=20Roh=C3=A1r?= , Lorenzo Pieralisi , =?UTF-8?q?Marek=20Beh=C3=BAn?= Subject: [PATCH 4.19 27/69] PCI: aardvark: Update comment about disabling link training Date: Mon, 29 Nov 2021 19:18:09 +0100 Message-Id: <20211129181704.557091873@linuxfoundation.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20211129181703.670197996@linuxfoundation.org> References: <20211129181703.670197996@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Pali Rohár commit 1d1cd163d0de22a4041a6f1aeabcf78f80076539 upstream. According to PCI Express Base Specifications (rev 4.0, 6.6.1 "Conventional reset"), after fundamental reset a 100ms delay is needed prior to enabling link training. Update comment in code to reflect this requirement. Link: https://lore.kernel.org/r/20201202184659.3795-1-pali@kernel.org Signed-off-by: Pali Rohár Signed-off-by: Lorenzo Pieralisi Signed-off-by: Marek Behún Signed-off-by: Greg Kroah-Hartman --- drivers/pci/controller/pci-aardvark.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) --- a/drivers/pci/controller/pci-aardvark.c +++ b/drivers/pci/controller/pci-aardvark.c @@ -236,7 +236,14 @@ static void advk_pcie_issue_perst(struct if (!pcie->reset_gpio) return; - /* PERST does not work for some cards when link training is enabled */ + /* + * As required by PCI Express spec (PCI Express Base Specification, REV. + * 4.0 PCI Express, February 19 2014, 6.6.1 Conventional Reset) a delay + * for at least 100ms after de-asserting PERST# signal is needed before + * link training is enabled. So ensure that link training is disabled + * prior de-asserting PERST# signal to fulfill that PCI Express spec + * requirement. + */ reg = advk_readl(pcie, PCIE_CORE_CTRL0_REG); reg &= ~LINK_TRAINING_EN; advk_writel(pcie, reg, PCIE_CORE_CTRL0_REG);