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 3902235B138; Mon, 20 Apr 2026 14:03:15 +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=1776693795; cv=none; b=V2LspLRA7dEzGn7s8USLyIsujF7hp+xj5+fs/Pt3VSXfomO/0W3ePckXEWHG0Np9GvWAyXUrTcDISy/Bedk25QQQnJPusqj4UY/cixIigg40R6k/mHIj4n4sVamam1BD3wfyS3XfTbITyKYTiVp6eHcV0CFDENOf3hmXW4OXuf8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776693795; c=relaxed/simple; bh=iLU6N2l2jgd4++DK662JYK8rj+h/DJ1uPLEdbKxpw5k=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=Xs7CczbiHNSLapRyUoYDqCG9xoWmlio+6/1VFVh8MzawMQv+kOlFXw3gquc2jLGKMkgLtGmluA3eTCBdmRERCeOixcQCKJHtS6/Bi98mgiowkLXy+3MR+Sfl761ECHTMh2FB14g4XrTrLjxMDHdxwYi1GUHonh2S1Q0QgOSqxe4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=oy/DQR2e; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="oy/DQR2e" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4744EC2BCB4; Mon, 20 Apr 2026 14:03:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1776693794; bh=iLU6N2l2jgd4++DK662JYK8rj+h/DJ1uPLEdbKxpw5k=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=oy/DQR2eGcF1Xm7ivYNsn6Afig/B1HtEoJRgttnjk5E09vB+/EONN1LyO3PEbehdc x0+rYINU2rBuPzw9ufo4O7NEw2erIsvBgv/zLHacLFXbqOl/97KJn5zu0NM0v+D8uq 08tA46P4EiGTNyZb3FaPCohqjO0vHcNZYtoi4Pw21QWMbvZIvNVZMzhlFFiaIUnPxW sllzf9cyybeTLl03q+Y2vLlHi9wSeNIT9U37KHgEyYz8QDhhAzi6Cqlff4sbugDPbZ p96FSJA+58xNwb0kN/0UkyIpl+AbHQWjQRxy8CrP1wE4u7zN7/DLFUemuKKnVPdDy5 di75GLz1biRww== Message-ID: Date: Mon, 20 Apr 2026 09:03:12 -0500 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4] platform/x86: dell-dw5826e: Add reset driver for DW5826e Content-Language: en-US To: Jack Wu , Hans de Goede , =?UTF-8?Q?Ilpo_J=C3=A4rvinen?= Cc: platform-driver-x86@vger.kernel.org, linux-kernel@vger.kernel.org References: <20260420060029.1754854-1-jackbb_wu@compal.com> From: Mario Limonciello In-Reply-To: <20260420060029.1754854-1-jackbb_wu@compal.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 4/20/26 01:00, Jack Wu wrote: > If the DW5826e is in a frozen state and unable to receive USB commands, > this driver provides a method for the user to reset the DW5826e via ACPI. > > E.g: echo 1 > /sys/bus/platform/devices/PALC0001\:00/wwan_reset > > Signed-off-by: Jack Wu Reviewed-by: Mario Limonciello (AMD) > --- > v4: > - Fix version of the ABI documentation to 7.2 > - Add include linux/types.h > v3: > - Rename sysfs attribute from "pldr" to "wwan_reset" for clarity > - Add ABI documentation for the wwan_reset sysfs interface > - Validate _DSM method availability in probe using acpi_check_dsm() > v2: > - Remove extra empty line > - Add missing includes and Remove unnecessary includes, sort includes alphabetically > - Remove noisy dev_info() > - Handle obj->type != ACPI_TYPE_BUFFER as error with proper return code > - Replace miscdevice/file_operations with sysfs attribute (DEVICE_ATTR_WO) to reduce boilerplate > - Propagate trigger_palc_pldr() return code to userspace > - Convert from acpi_driver to platform_driver > --- > --- > .../testing/sysfs-driver-dell-dw5826e-reset | 9 ++ > drivers/platform/x86/dell/Kconfig | 6 ++ > drivers/platform/x86/dell/Makefile | 2 + > .../platform/x86/dell/dell-dw5826e-reset.c | 90 +++++++++++++++++++ > 4 files changed, 107 insertions(+) > create mode 100644 Documentation/ABI/testing/sysfs-driver-dell-dw5826e-reset > create mode 100644 drivers/platform/x86/dell/dell-dw5826e-reset.c > > diff --git a/Documentation/ABI/testing/sysfs-driver-dell-dw5826e-reset b/Documentation/ABI/testing/sysfs-driver-dell-dw5826e-reset > new file mode 100644 > index 000000000000..a665e265633f > --- /dev/null > +++ b/Documentation/ABI/testing/sysfs-driver-dell-dw5826e-reset > @@ -0,0 +1,9 @@ > +What: /sys/bus/platform/devices//wwan_reset > +Date: April 2026 > +KernelVersion: 7.2 > +Contact: Jackbb Wu > +Description: > + Writing to this file triggers a Platform Level Device Reset > + (PLDR) of the Dell DW5826e WWAN module via an ACPI _DSM > + method. This can be used to recover the modem when it is in > + a frozen state and unable to respond to USB commands. > diff --git a/drivers/platform/x86/dell/Kconfig b/drivers/platform/x86/dell/Kconfig > index 738c108c2163..c4540c837a88 100644 > --- a/drivers/platform/x86/dell/Kconfig > +++ b/drivers/platform/x86/dell/Kconfig > @@ -276,4 +276,10 @@ config DELL_WMI_SYSMAN > To compile this driver as a module, choose M here: the module will > be called dell-wmi-sysman. > > +config DELL_DW5826E_RESET > + tristate "Dell DW5826e PLDR reset support" > + default m > + depends on ACPI > + help > + This adds support for the Dell DW5826e PLDR reset via ACPI > endif # X86_PLATFORM_DRIVERS_DELL > diff --git a/drivers/platform/x86/dell/Makefile b/drivers/platform/x86/dell/Makefile > index c7501c25e627..8150283cfd1d 100644 > --- a/drivers/platform/x86/dell/Makefile > +++ b/drivers/platform/x86/dell/Makefile > @@ -28,3 +28,5 @@ obj-$(CONFIG_DELL_WMI_DESCRIPTOR) += dell-wmi-descriptor.o > obj-$(CONFIG_DELL_WMI_DDV) += dell-wmi-ddv.o > obj-$(CONFIG_DELL_WMI_LED) += dell-wmi-led.o > obj-$(CONFIG_DELL_WMI_SYSMAN) += dell-wmi-sysman/ > +obj-$(CONFIG_DELL_DW5826E_RESET) += dell-dw5826e-reset.o > + > diff --git a/drivers/platform/x86/dell/dell-dw5826e-reset.c b/drivers/platform/x86/dell/dell-dw5826e-reset.c > new file mode 100644 > index 000000000000..4e0d64535abb > --- /dev/null > +++ b/drivers/platform/x86/dell/dell-dw5826e-reset.c > @@ -0,0 +1,90 @@ > +// SPDX-License-Identifier: GPL-2.0-or-later > +/* > + * dell-dw5826e-reset.c - Dell DW5826e reset driver > + * > + * Copyright (C) 2026 Jackbb Wu > + */ > + > +#include > +#include > +#include > +#include > +#include > +#include > + > +static guid_t palc_dsm_guid = > + GUID_INIT(0x5a1a4bba, 0x8006, 0x487e, 0xbe, 0x0a, 0xac, 0xf5, 0xd8, 0xfd, 0xfe, 0x59); > + > +static int trigger_palc_pldr(struct device *dev, acpi_handle handle) > +{ > + union acpi_object *obj; > + int ret = 0; > + > + obj = acpi_evaluate_dsm(handle, &palc_dsm_guid, 1, 1, NULL); > + if (!obj) { > + dev_err(dev, "Failed to evaluate _DSM\n"); > + return -EIO; > + } > + > + if (obj->type != ACPI_TYPE_BUFFER) { > + dev_err(dev, "Unexpected _DSM return type: %d\n", obj->type); > + ret = -EINVAL; > + } > + > + ACPI_FREE(obj); > + return ret; > +} > + > +static ssize_t wwan_reset_store(struct device *dev, struct device_attribute *attr, > + const char *buf, size_t count) > +{ > + acpi_handle handle = ACPI_HANDLE(dev); > + int ret; > + > + ret = trigger_palc_pldr(dev, handle); > + if (ret) > + return ret; > + > + return count; > +} > +static DEVICE_ATTR_WO(wwan_reset); > + > +static struct attribute *palc_attrs[] = { > + &dev_attr_wwan_reset.attr, > + NULL > +}; > +ATTRIBUTE_GROUPS(palc); > + > +static int palc_probe(struct platform_device *pdev) > +{ > + acpi_handle handle; > + > + handle = ACPI_HANDLE(&pdev->dev); > + if (!handle) > + return -ENODEV; > + > + if (!acpi_check_dsm(handle, &palc_dsm_guid, 1, BIT(1))) > + return -ENODEV; > + > + return 0; > +} > + > +static const struct acpi_device_id palc_acpi_ids[] = { > + { "PALC0001", 0 }, > + { } > +}; > +MODULE_DEVICE_TABLE(acpi, palc_acpi_ids); > + > +static struct platform_driver palc_driver = { > + .driver = { > + .name = "dell-dw5826e-reset", > + .acpi_match_table = palc_acpi_ids, > + .dev_groups = palc_groups, > + }, > + .probe = palc_probe, > +}; > +module_platform_driver(palc_driver); > + > +MODULE_DESCRIPTION("Dell DW5826e reset driver"); > +MODULE_LICENSE("GPL"); > +MODULE_AUTHOR("JackBB Wu");