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 71606CCA483 for ; Tue, 7 Jun 2022 21:27:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1379542AbiFGVZr (ORCPT ); Tue, 7 Jun 2022 17:25:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59714 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1359370AbiFGU2t (ORCPT ); Tue, 7 Jun 2022 16:28:49 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 544201DE2CA; Tue, 7 Jun 2022 11:34:06 -0700 (PDT) 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 ams.source.kernel.org (Postfix) with ESMTPS id C8487B8237C; Tue, 7 Jun 2022 18:34:04 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 20044C385A2; Tue, 7 Jun 2022 18:34:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1654626843; bh=KuBggibQ2kdcdl6AKmQWBZtOYCkJvlXn2LcbUtvG/BE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=DUsuFfp/go0V79BqtXeQsYLj5NRzE89AHtELw8Jr3VKpVv60zoXT/cCXN8kswHYxk nDFShr12XCjcwNl4YUqpZeLX6LJJ09S6n17PLOd5NJREvZiTz2gpW3MHX5z+5UwZPe MSpIWg9bwsi2wGhwNzqPGYx8gUVJZLt5UtQBZf1Q= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Francesco Dolcini , Lorenzo Pieralisi , Lucas Stach , Richard Zhu , Sasha Levin Subject: [PATCH 5.17 525/772] PCI: imx6: Fix PERST# start-up sequence Date: Tue, 7 Jun 2022 19:01:57 +0200 Message-Id: <20220607165004.444815841@linuxfoundation.org> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220607164948.980838585@linuxfoundation.org> References: <20220607164948.980838585@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: Francesco Dolcini [ Upstream commit a6809941c1f17f455db2cf4ca19c6d8c8746ec25 ] According to the PCIe standard the PERST# signal (reset-gpio in fsl,imx* compatible dts) should be kept asserted for at least 100 usec before the PCIe refclock is stable, should be kept asserted for at least 100 msec after the power rails are stable and the host should wait at least 100 msec after it is de-asserted before accessing the configuration space of any attached device. >>From PCIe CEM r2.0, sec 2.6.2 T-PVPERL: Power stable to PERST# inactive - 100 msec T-PERST-CLK: REFCLK stable before PERST# inactive - 100 usec. >>From PCIe r5.0, sec 6.6.1 With a Downstream Port that does not support Link speeds greater than 5.0 GT/s, software must wait a minimum of 100 ms before sending a Configuration Request to the device immediately below that Port. Failure to do so could prevent PCIe devices to be working correctly, and this was experienced with real devices. Move reset assert to imx6_pcie_assert_core_reset(), this way we ensure that PERST# is asserted before enabling any clock, move de-assert to the end of imx6_pcie_deassert_core_reset() after the clock is enabled and deemed stable and add a new delay of 100 msec just afterward. Link: https://lore.kernel.org/all/20220211152550.286821-1-francesco.dolcini@toradex.com Link: https://lore.kernel.org/r/20220404081509.94356-1-francesco.dolcini@toradex.com Fixes: bb38919ec56e ("PCI: imx6: Add support for i.MX6 PCIe controller") Signed-off-by: Francesco Dolcini Signed-off-by: Lorenzo Pieralisi Reviewed-by: Lucas Stach Acked-by: Richard Zhu Signed-off-by: Sasha Levin --- drivers/pci/controller/dwc/pci-imx6.c | 23 ++++++++++++++--------- 1 file changed, 14 insertions(+), 9 deletions(-) diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c index 343fe1429e3c..ce3a36d1f2fa 100644 --- a/drivers/pci/controller/dwc/pci-imx6.c +++ b/drivers/pci/controller/dwc/pci-imx6.c @@ -408,6 +408,11 @@ static void imx6_pcie_assert_core_reset(struct imx6_pcie *imx6_pcie) dev_err(dev, "failed to disable vpcie regulator: %d\n", ret); } + + /* Some boards don't have PCIe reset GPIO. */ + if (gpio_is_valid(imx6_pcie->reset_gpio)) + gpio_set_value_cansleep(imx6_pcie->reset_gpio, + imx6_pcie->gpio_active_high); } static unsigned int imx6_pcie_grp_offset(const struct imx6_pcie *imx6_pcie) @@ -540,15 +545,6 @@ static void imx6_pcie_deassert_core_reset(struct imx6_pcie *imx6_pcie) /* allow the clocks to stabilize */ usleep_range(200, 500); - /* Some boards don't have PCIe reset GPIO. */ - if (gpio_is_valid(imx6_pcie->reset_gpio)) { - gpio_set_value_cansleep(imx6_pcie->reset_gpio, - imx6_pcie->gpio_active_high); - msleep(100); - gpio_set_value_cansleep(imx6_pcie->reset_gpio, - !imx6_pcie->gpio_active_high); - } - switch (imx6_pcie->drvdata->variant) { case IMX8MQ: reset_control_deassert(imx6_pcie->pciephy_reset); @@ -595,6 +591,15 @@ static void imx6_pcie_deassert_core_reset(struct imx6_pcie *imx6_pcie) break; } + /* Some boards don't have PCIe reset GPIO. */ + if (gpio_is_valid(imx6_pcie->reset_gpio)) { + msleep(100); + gpio_set_value_cansleep(imx6_pcie->reset_gpio, + !imx6_pcie->gpio_active_high); + /* Wait for 100ms after PERST# deassertion (PCIe r5.0, 6.6.1) */ + msleep(100); + } + return; err_ref_clk: -- 2.35.1