releases/6.8.6/acpi-x86-add-dell0501-handling-to-acpi_quirk_skip_se.patch

   1 From 877522169dbf76d5aec093fee58ecf835169dd0f Mon Sep 17 00:00:00 2001
   2 From: Sasha Levin <sashal@kernel.org>
   3 Date: Sun, 18 Feb 2024 16:15:33 +0100
   4 Subject: ACPI: x86: Add DELL0501 handling to
   5  acpi_quirk_skip_serdev_enumeration()
   6
   7 From: Hans de Goede <hdegoede@redhat.com>
   8
   9 [ Upstream commit 99b572e6136eab69a8c91d72cf8595b256e304b5 ]
  10
  11 Some recent(ish) Dell AIO devices have a backlight controller board
  12 connected to an UART.
  13
  14 This UART has a DELL0501 HID with CID set to PNP0501 so that the UART is
  15 still handled by 8250_pnp.c. Unfortunately there is no separate ACPI device
  16 with an UartSerialBusV2() resource to model the backlight-controller.
  17 This causes the kernel to create a /dev/ttyS0 char-device for the UART
  18 instead of creating an in kernel serdev-controller + serdev-device pair
  19 for a kernel backlight driver.
  20
  21 Use the existing acpi_quirk_skip_serdev_enumeration() mechanism to work
  22 around this by returning skip=true for tty-ctrl parents with a HID
  23 of DELL0501.
  24
  25 Like other cases where the UartSerialBusV2() resource is missing or broken
  26 this will only create the serdev-controller device and the serdev-device
  27 itself will need to be instantiated by platform code.
  28
  29 Unfortunately in this case there is no device for the platform-code
  30 instantiating the serdev-device to bind to. So also create
  31 a platform_device for this.
  32
  33 Signed-off-by: Hans de Goede <hdegoede@redhat.com>
  34 Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
  35 Signed-off-by: Sasha Levin <sashal@kernel.org>
  36 ---
  37  drivers/acpi/x86/utils.c | 20 ++++++++++++++++++++
  38  1 file changed, 20 insertions(+)
  39
  40 diff --git a/drivers/acpi/x86/utils.c b/drivers/acpi/x86/utils.c
  41 index 8829a907eee02..90c3d2eab9e99 100644
  42 --- a/drivers/acpi/x86/utils.c
  43 +++ b/drivers/acpi/x86/utils.c
  44 @@ -484,8 +484,28 @@ static int acpi_dmi_skip_serdev_enumeration(struct device *controller_parent, bo
  45
  46  int acpi_quirk_skip_serdev_enumeration(struct device *controller_parent, bool *skip)
  47  {
  48 +       struct acpi_device *adev = ACPI_COMPANION(controller_parent);
  49 +
  50         *skip = false;
  51
  52 +       /*
  53 +        * The DELL0501 ACPI HID represents an UART (CID is set to PNP0501) with
  54 +        * a backlight-controller attached. There is no separate ACPI device with
  55 +        * an UartSerialBusV2() resource to model the backlight-controller.
  56 +        * Set skip to true so that the tty core creates a serdev ctrl device.
  57 +        * The backlight driver will manually create the serdev client device.
  58 +        */
  59 +       if (acpi_dev_hid_match(adev, "DELL0501")) {
  60 +               *skip = true;
  61 +               /*
  62 +                * Create a platform dev for dell-uart-backlight to bind to.
  63 +                * This is a static device, so no need to store the result.
  64 +                */
  65 +               platform_device_register_simple("dell-uart-backlight", PLATFORM_DEVID_NONE,
  66 +                                               NULL, 0);
  67 +               return 0;
  68 +       }
  69 +
  70         return acpi_dmi_skip_serdev_enumeration(controller_parent, skip);
  71  }
  72  EXPORT_SYMBOL_GPL(acpi_quirk_skip_serdev_enumeration);
  73 --
  74 2.43.0
  75