drivers/platform/x86/dell/Kconfig | 6 ++ drivers/platform/x86/dell/Makefile | 2 + .../platform/x86/dell/dell-dw5826e-reset.c | 83 +++++++++++++++++++ 3 files changed, 91 insertions(+) create mode 100644 drivers/platform/x86/dell/dell-dw5826e-reset.c
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/pldr
Signed-off-by: Jack Wu <jackbb_wu@compal.com>
---
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
---
---
drivers/platform/x86/dell/Kconfig | 6 ++
drivers/platform/x86/dell/Makefile | 2 +
.../platform/x86/dell/dell-dw5826e-reset.c | 83 +++++++++++++++++++
3 files changed, 91 insertions(+)
create mode 100644 drivers/platform/x86/dell/dell-dw5826e-reset.c
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..52002578ed68
--- /dev/null
+++ b/drivers/platform/x86/dell/dell-dw5826e-reset.c
@@ -0,0 +1,83 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * dell-dw5826e-reset.c - Dell DW5826e reset driver
+ *
+ * Copyright (C) 2026 Jackbb Wu <jackbb.wu@compal.com>
+ */
+
+#include <linux/acpi.h>
+#include <linux/device.h>
+#include <linux/uuid.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+
+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 pldr_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(pldr);
+
+static struct attribute *palc_attrs[] = {
+ &dev_attr_pldr.attr,
+ NULL
+};
+ATTRIBUTE_GROUPS(palc);
+
+static int palc_probe(struct platform_device *pdev)
+{
+ if (!ACPI_HANDLE(&pdev->dev))
+ 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");
--
2.34.1
Am 10.04.26 um 11:37 schrieb Jack Wu:
> 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/pldr
>
> Signed-off-by: Jack Wu <jackbb_wu@compal.com>
> ---
> 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
> ---
> ---
> drivers/platform/x86/dell/Kconfig | 6 ++
> drivers/platform/x86/dell/Makefile | 2 +
> .../platform/x86/dell/dell-dw5826e-reset.c | 83 +++++++++++++++++++
> 3 files changed, 91 insertions(+)
> create mode 100644 drivers/platform/x86/dell/dell-dw5826e-reset.c
>
> 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..52002578ed68
> --- /dev/null
> +++ b/drivers/platform/x86/dell/dell-dw5826e-reset.c
> @@ -0,0 +1,83 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * dell-dw5826e-reset.c - Dell DW5826e reset driver
> + *
> + * Copyright (C) 2026 Jackbb Wu <jackbb.wu@compal.com>
> + */
> +
> +#include <linux/acpi.h>
> +#include <linux/device.h>
> +#include <linux/uuid.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +
> +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 pldr_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(pldr);
> +
> +static struct attribute *palc_attrs[] = {
> + &dev_attr_pldr.attr,
> + NULL
> +};
> +ATTRIBUTE_GROUPS(palc);
> +
> +static int palc_probe(struct platform_device *pdev)
> +{
> + if (!ACPI_HANDLE(&pdev->dev))
> + return -ENODEV;
> +
Hi, please check here if the _DSM method exists using acpi_check_dsm().
Thanks,
Armin Wolf
> + 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");
Thanks for the feedback. I add the sysfs ABI documentation in
Documentation/ABI/testing/ and fix other issue. they include it in the
v3 version of the patch.
Armin Wolf <W_Armin@gmx.de> 於 2026年4月13日週一 下午2:21寫道:
>
> Am 10.04.26 um 11:37 schrieb Jack Wu:
> > 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/pldr
> >
> > Signed-off-by: Jack Wu <jackbb_wu@compal.com>
> > ---
> > 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
> > ---
> > ---
> > drivers/platform/x86/dell/Kconfig | 6 ++
> > drivers/platform/x86/dell/Makefile | 2 +
> > .../platform/x86/dell/dell-dw5826e-reset.c | 83 +++++++++++++++++++
> > 3 files changed, 91 insertions(+)
> > create mode 100644 drivers/platform/x86/dell/dell-dw5826e-reset.c
> >
> > 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..52002578ed68
> > --- /dev/null
> > +++ b/drivers/platform/x86/dell/dell-dw5826e-reset.c
> > @@ -0,0 +1,83 @@
> > +// SPDX-License-Identifier: GPL-2.0-or-later
> > +/*
> > + * dell-dw5826e-reset.c - Dell DW5826e reset driver
> > + *
> > + * Copyright (C) 2026 Jackbb Wu <jackbb.wu@compal.com>
> > + */
> > +
> > +#include <linux/acpi.h>
> > +#include <linux/device.h>
> > +#include <linux/uuid.h>
> > +#include <linux/module.h>
> > +#include <linux/platform_device.h>
> > +
> > +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 pldr_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(pldr);
> > +
> > +static struct attribute *palc_attrs[] = {
> > + &dev_attr_pldr.attr,
> > + NULL
> > +};
> > +ATTRIBUTE_GROUPS(palc);
> > +
> > +static int palc_probe(struct platform_device *pdev)
> > +{
> > + if (!ACPI_HANDLE(&pdev->dev))
> > + return -ENODEV;
> > +
>
> Hi, please check here if the _DSM method exists using acpi_check_dsm().
>
> Thanks,
> Armin Wolf
>
> > + 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");
>
On 4/10/26 04:37, Jack Wu wrote:
> [You don't often get email from wojackbb@gmail.com. Learn why this is important at https://aka.ms/LearnAboutSenderIdentification ]
>
> 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/pldr
>
> Signed-off-by: Jack Wu <jackbb_wu@compal.com>
> ---
> 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
> ---
Generally speaking this looks much better. The only thing missing to me
is documentation to go with it since it won't be obvious to a user what
the "pldr" sysfs file represents.
Also in that sense - if the ACPI PALC0001 device will always represent
WWAN reset, then maybe the sysfs file should also be called wwan_reset
instead of pldr (platform device reset).
> ---
> drivers/platform/x86/dell/Kconfig | 6 ++
> drivers/platform/x86/dell/Makefile | 2 +
> .../platform/x86/dell/dell-dw5826e-reset.c | 83 +++++++++++++++++++
> 3 files changed, 91 insertions(+)
> create mode 100644 drivers/platform/x86/dell/dell-dw5826e-reset.c
>
> 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..52002578ed68
> --- /dev/null
> +++ b/drivers/platform/x86/dell/dell-dw5826e-reset.c
> @@ -0,0 +1,83 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * dell-dw5826e-reset.c - Dell DW5826e reset driver
> + *
> + * Copyright (C) 2026 Jackbb Wu <jackbb.wu@compal.com>
> + */
> +
> +#include <linux/acpi.h>
> +#include <linux/device.h>
> +#include <linux/uuid.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +
> +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 pldr_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(pldr);
> +
> +static struct attribute *palc_attrs[] = {
> + &dev_attr_pldr.attr,
> + NULL
> +};
> +ATTRIBUTE_GROUPS(palc);
> +
> +static int palc_probe(struct platform_device *pdev)
> +{
> + if (!ACPI_HANDLE(&pdev->dev))
> + 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");
> --
> 2.34.1
>
>
© 2016 - 2026 Red Hat, Inc.