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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 5200ECD128A for ; Sun, 31 Mar 2024 19:35:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:Content-Type: Content-Transfer-Encoding:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:Message-ID:References:In-Reply-To:Subject:Cc:To:From :Date:MIME-Version:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=la6EYpibeH64Q7bqWDHDdQwVH9TyHGj6sZ+Koahmdpg=; b=RhLkGDP98PepwzLhpSctUBkFRO h0wCJW7FFdtO41S2mQPFFWZaTwHuRxi6yP42uziB44xVYgPT7tbfcucKWsQLumpilJCWYGilgLUH/ I9ewqRSHxrsj7JoXaI3WqYWJIPbQKhqueQ5jm+jyqwxgxm+Qiz79a6yJVVcM/1t0ceiSLHZQ/usFc oKAlGpRsQ/LHkXVgQwgFmlcU0trbjF7OX7fArFGlt0+AIRe1hsJwPk6A9/W8r9Q/PEBhrv2kEz5QQ 09uEk9EsJrMt6bfHH5wpbds7WOL0bp4TQR2r+30RxLJwZTGibgsNmFxaw7k4sL+t7OZNOPylloShF aCvaAYGQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1rr0x6-00000006B1g-1IQy; Sun, 31 Mar 2024 19:34:48 +0000 Received: from mail.manjaro.org ([116.203.91.91]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1rr0x2-00000006B0T-26kF; Sun, 31 Mar 2024 19:34:46 +0000 MIME-Version: 1.0 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=manjaro.org; s=2021; t=1711913682; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=t6Yrm2TEKB8mxEWaCaPBLV4zJHwlikBx3tCoJxDGcRs=; b=A4ZcmH2V1Wx+hrnRjvCuttpggRP8JQh4k/CJWnEaIflJmQ4Ykr0sxPVHDJWu6F8lrpTKSl dHoFPhacrJvK83ZVI4IBC5vNSTuxD7cd8MhPCSgFFM5KQiJu7V8lmxkLGO5Oe8fUYsX/LY JHJyGJQL7RF0czrSCDK3mjn0IqPU6SKJ2FNAT0ALmVs/QvxjvplEFPJbvgPrr/430HFk7M 7yuaNyW85GVwU2GIMOUww1OI/uDUOO/8hEyW2sOr7zI6ClSrIxLyYvJyDW1Jvw7S0lKU4J vFyj2tTfR6Bn0OWhQfIplrKpPRPnBQSVrcNsbrGQ7jXj8PewbzURydd6bBORaw== Date: Sun, 31 Mar 2024 21:34:42 +0200 From: Dragan Simic To: Damien Le Moal Cc: Shawn Lin , Bjorn Helgaas , Heiko Stuebner , linux-pci@vger.kernel.org, Lorenzo Pieralisi , =?UTF-8?Q?Krzysztof_Wilczy=C5=84ski?= , linux-rockchip@lists.infradead.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v2] PCI: rockchip-host: Fix rockchip_pcie_host_init_port() PERST# handling In-Reply-To: <20240330035043.1546087-1-dlemoal@kernel.org> References: <20240330035043.1546087-1-dlemoal@kernel.org> Message-ID: X-Sender: dsimic@manjaro.org Authentication-Results: ORIGINATING; auth=pass smtp.auth=dsimic@manjaro.org smtp.mailfrom=dsimic@manjaro.org X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240331_123444_875469_4FA307E8 X-CRM114-Status: GOOD ( 19.13 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hello Damien, Please see my comments below. On 2024-03-30 04:50, Damien Le Moal wrote: > The PCIe specifications (PCI Express Electromechanical Specification > rev > 2.0, section 2.6.2) mandate that the PERST# signal must remain asserted > for at least 100 usec (Tperst-clk) after the PCIe reference clock > becomes stable (if a reference clock is supplied), for at least 100 > msec > after the power is stable (Tpvperl). > > In addition, the PCI Express Base SPecification Rev 2.0, section 6.6.1 > state that the host should wait for at least 100 msec from the end of a > conventional reset (PERST# is de-asserted) before accessing the > configuration space of the attached device. > > Modify rockchip_pcie_host_init_port() by adding two 100ms sleep, one > before and after bringing back PESRT signal to high using the ep_gpio > GPIO. Comments are also added to clarify this behavior. > > Signed-off-by: Damien Le Moal > --- > > Changes from v1: > - Add more specification details to the commit message. > - Add missing msleep(100) after PERST# is deasserted. > > drivers/pci/controller/pcie-rockchip-host.c | 12 ++++++++++++ > 1 file changed, 12 insertions(+) > > diff --git a/drivers/pci/controller/pcie-rockchip-host.c > b/drivers/pci/controller/pcie-rockchip-host.c > index 300b9dc85ecc..ff2fa27bd883 100644 > --- a/drivers/pci/controller/pcie-rockchip-host.c > +++ b/drivers/pci/controller/pcie-rockchip-host.c > @@ -294,6 +294,7 @@ static int rockchip_pcie_host_init_port(struct > rockchip_pcie *rockchip) > int err, i = MAX_LANE_NUM; > u32 status; > > + /* Assert PERST */ > gpiod_set_value_cansleep(rockchip->ep_gpio, 0); > > err = rockchip_pcie_init_port(rockchip); > @@ -322,8 +323,19 @@ static int rockchip_pcie_host_init_port(struct > rockchip_pcie *rockchip) > rockchip_pcie_write(rockchip, PCIE_CLIENT_LINK_TRAIN_ENABLE, > PCIE_CLIENT_CONFIG); > > + /* > + * PCIe CME specifications mandate that PERST be asserted for at > + * least 100ms after power is stable. > + */ > + msleep(100); Perhaps it would be slightly better to use usleep_range() instead of msleep(). > gpiod_set_value_cansleep(rockchip->ep_gpio, 1); > > + /* > + * PCIe base specifications rev 2.0 mandate that the host wait for > + * 100ms after completion of a conventional reset. > + */ > + msleep(100); Obviously, the same comment as above applies here. > + > /* 500ms timeout value should be enough for Gen1/2 training */ > err = readl_poll_timeout(rockchip->apb_base + > PCIE_CLIENT_BASIC_STATUS1, > status, PCIE_LINK_UP(status), 20, _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel