From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 E460A1A76BC; Thu, 15 Aug 2024 13:33:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723728787; cv=none; b=ktOYKsk+/BtDG/YG1+DzG71g9POchH27qxpLY/4Tnj0ISur+Iupy7YkyBopw658nqNdiNQKOCHnzEnfeEdnWuDiHAKCd3BX3PM5C+7gS7P6CHVrSgsuz8O0NkOGidZXTcZI5fFk/pU8ytv+0x4+9MO17BcdLj6Zl38pmv1mjLZw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723728787; c=relaxed/simple; bh=d/oaxdFHOw1VAdWIW6ggiIlBeUWboaZuDHjdO2zh0hQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=VM7KOq0HrE86rv86eiIjG5brIH5lw83eHlpvxOKe8Uix1TlhuTByoBh1eCWWzW/OXANXULv13iAxjXc4Pq0TfGvZRV5oTBqyAbgxtjejoG9252CMQggDhBFsMmLmo6rC8WT9TgwvLx1YqA/iOg4n10mM1pIGCWrszbyAS34Ozm4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=hCjkVZFV; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="hCjkVZFV" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6988AC4AF0E; Thu, 15 Aug 2024 13:33:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1723728786; bh=d/oaxdFHOw1VAdWIW6ggiIlBeUWboaZuDHjdO2zh0hQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=hCjkVZFVSwzAHg+I5cccHvqt0xmxBz478jPzk0TFEEb0/mJt9tEm/1J4dBJ1NG0mE fnEeCD8gaOU/iS+wn3vI22j6PluRxmeWn9ekTXKH4UEgpHX4b69K24LQd3F34t9Kzl v2xH7T8FZD6v7YkPGppj/JUWl+K1bYHdyr3Uj2uI= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Slark Xiao , Manivannan Sadhasivam , =?UTF-8?q?Krzysztof=20Wilczy=C5=84ski?= , Bjorn Helgaas , Niklas Cassel , Sasha Levin Subject: [PATCH 4.19 108/196] PCI: rockchip: Use GPIOD_OUT_LOW flag while requesting ep_gpio Date: Thu, 15 Aug 2024 15:23:45 +0200 Message-ID: <20240815131856.211591874@linuxfoundation.org> X-Mailer: git-send-email 2.46.0 In-Reply-To: <20240815131852.063866671@linuxfoundation.org> References: <20240815131852.063866671@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 4.19-stable review patch. If anyone has any objections, please let me know. ------------------ From: Manivannan Sadhasivam [ Upstream commit 840b7a5edf88fe678c60dee88a135647c0ea4375 ] Rockchip platforms use 'GPIO_ACTIVE_HIGH' flag in the devicetree definition for ep_gpio. This means, whatever the logical value set by the driver for the ep_gpio, physical line will output the same logic level. For instance, gpiod_set_value_cansleep(rockchip->ep_gpio, 0); --> Level low gpiod_set_value_cansleep(rockchip->ep_gpio, 1); --> Level high But while requesting the ep_gpio, GPIOD_OUT_HIGH flag is currently used. Now, this also causes the physical line to output 'high' creating trouble for endpoint devices during host reboot. When host reboot happens, the ep_gpio will initially output 'low' due to the GPIO getting reset to its POR value. Then during host controller probe, it will output 'high' due to GPIOD_OUT_HIGH flag. Then during rockchip_pcie_host_init_port(), it will first output 'low' and then 'high' indicating the completion of controller initialization. On the endpoint side, each output 'low' of ep_gpio is accounted for PERST# assert and 'high' for PERST# deassert. With the above mentioned flow during host reboot, endpoint will witness below state changes for PERST#: (1) PERST# assert - GPIO POR state (2) PERST# deassert - GPIOD_OUT_HIGH while requesting GPIO (3) PERST# assert - rockchip_pcie_host_init_port() (4) PERST# deassert - rockchip_pcie_host_init_port() Now the time interval between (2) and (3) is very short as both happen during the driver probe(), and this results in a race in the endpoint. Because, before completing the PERST# deassertion in (2), endpoint got another PERST# assert in (3). A proper way to fix this issue is to change the GPIOD_OUT_HIGH flag in (2) to GPIOD_OUT_LOW. Because the usual convention is to request the GPIO with a state corresponding to its 'initial/default' value and let the driver change the state of the GPIO when required. As per that, the ep_gpio should be requested with GPIOD_OUT_LOW as it corresponds to the POR value of '0' (PERST# assert in the endpoint). Then the driver can change the state of the ep_gpio later in rockchip_pcie_host_init_port() as per the initialization sequence. This fixes the firmware crash issue in Qcom based modems connected to Rockpro64 based board. Fixes: e77f847df54c ("PCI: rockchip: Add Rockchip PCIe controller support") Closes: https://lore.kernel.org/mhi/20240402045647.GG2933@thinkpad/ Link: https://lore.kernel.org/linux-pci/20240416-pci-rockchip-perst-fix-v1-1-4800b1d4d954@linaro.org Reported-by: Slark Xiao Signed-off-by: Manivannan Sadhasivam Signed-off-by: Krzysztof Wilczyński Signed-off-by: Bjorn Helgaas Reviewed-by: Niklas Cassel Cc: stable@vger.kernel.org # v4.9 Signed-off-by: Sasha Levin --- drivers/pci/controller/pcie-rockchip.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/pci/controller/pcie-rockchip.c b/drivers/pci/controller/pcie-rockchip.c index c6d2f00acf890..6ab7ca0b9bf9e 100644 --- a/drivers/pci/controller/pcie-rockchip.c +++ b/drivers/pci/controller/pcie-rockchip.c @@ -121,7 +121,7 @@ int rockchip_pcie_parse_dt(struct rockchip_pcie *rockchip) if (rockchip->is_rc) { rockchip->ep_gpio = devm_gpiod_get_optional(dev, "ep", - GPIOD_OUT_HIGH); + GPIOD_OUT_LOW); if (IS_ERR(rockchip->ep_gpio)) return dev_err_probe(dev, PTR_ERR(rockchip->ep_gpio), "failed to get ep GPIO\n"); -- 2.43.0