[Intel-gfx] [PATCH] ACPI: Fix selecting the wrong ACPI fwnode for the iGPU on some Dell laptops

[Intel-gfx] [PATCH] ACPI: Fix selecting the wrong ACPI fwnode for the iGPU on some Dell laptops

[Hans de Goede]

The Dell Latitude E6430 both with and without the optional NVidia dGPU
has a bug in its ACPI tables which is causing Linux to assign the wrong
ACPI fwnode / companion to the pci_device for the i915 iGPU.

Specifically under the PCI root bridge there are these 2 ACPI Device()s :

 Scope (_SB.PCI0)
 {
     Device (GFX0)
     {
         Name (_ADR, 0x00020000)  // _ADR: Address
     }

     ...

     Device (VID)
     {
         Name (_ADR, 0x00020000)  // _ADR: Address
         ...

         Method (_DOS, 1, NotSerialized)  // _DOS: Disable Output Switching
         {
             VDP8 = Arg0
             VDP1 (One, VDP8)
         }

         Method (_DOD, 0, NotSerialized)  // _DOD: Display Output Devices
         {
             ...
         }
         ...
     }
 }

The non-functional GFX0 ACPI device is a problem, because this gets
returned as ACPI companion-device by acpi_find_child_device() for the iGPU.

This is a long standing problem and the i915 driver does use the ACPI
companion for some things, but works fine without it.

However since commit 63f534b8bad9 ("ACPI: PCI: Rework acpi_get_pci_dev()")
acpi_get_pci_dev() relies on the physical-node pointer in the acpi_device
and that is set on the wrong acpi_device because of the wrong
acpi_find_child_device() return. This breaks the ACPI video code, leading
to non working backlight control in some cases.

Make find_child_checks() return a higher score for children which have
pnp-ids set by various scan helpers like acpi_is_video_device(), so
that it picks the right companion-device.

An alternative approach would be to directly call acpi_is_video_device()
from find_child_checks() but that would be somewhat computationally
expensive given that acpi_find_child_device() iterates over all the
PCI0 children every time it is called.

Fixes: 63f534b8bad9 ("ACPI: PCI: Rework acpi_get_pci_dev()")
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
 drivers/acpi/glue.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/acpi/glue.c b/drivers/acpi/glue.c
index 204fe94c7e45..2055dfd7678b 100644
--- a/drivers/acpi/glue.c
+++ b/drivers/acpi/glue.c
@@ -75,7 +75,7 @@ static struct acpi_bus_type *acpi_get_bus_type(struct device *dev)
 }
 
 #define FIND_CHILD_MIN_SCORE	1
-#define FIND_CHILD_MAX_SCORE	2
+#define FIND_CHILD_MAX_SCORE	3
 
 static int match_any(struct acpi_device *adev, void *not_used)
 {
@@ -89,15 +89,25 @@ static bool acpi_dev_has_children(struct acpi_device *adev)
 
 static int find_child_checks(struct acpi_device *adev, bool check_children)
 {
+	int score = FIND_CHILD_MIN_SCORE;
 	unsigned long long sta;
 	acpi_status status;
 
 	if (check_children && !acpi_dev_has_children(adev))
 		return -ENODEV;
 
+	/*
+	 * For devices without a _STA method, prefer devices without a _HID
+	 * (which conflicts with having an _ADR) but which have been matched
+	 * in some other way, like e.g. by acpi_is_video_device() over devices
+	 * with no ids at all.
+	 */
+	if (!adev->pnp.type.platform_id && adev->pnp.type.hardware_id)
+		score++;
+
 	status = acpi_evaluate_integer(adev->handle, "_STA", NULL, &sta);
 	if (status == AE_NOT_FOUND)
-		return FIND_CHILD_MIN_SCORE;
+		return score;
 
 	if (ACPI_FAILURE(status) || !(sta & ACPI_STA_DEVICE_ENABLED))
 		return -ENODEV;
-- 
2.39.0

Re: [Intel-gfx] [PATCH] ACPI: Fix selecting the wrong ACPI fwnode for the iGPU on some Dell laptops

[Hans de Goede]

p.s.

This fixes a regression in 6.1, adding the regressions list to the Cc.

Once we figure out the best way to fix this (this patch is more of a proposal
how to fix this rather then a definitive fix), we should also backport
the fix to 6.1.y.


On 1/9/23 21:57, Hans de Goede wrote:
> The Dell Latitude E6430 both with and without the optional NVidia dGPU
> has a bug in its ACPI tables which is causing Linux to assign the wrong
> ACPI fwnode / companion to the pci_device for the i915 iGPU.
> 
> Specifically under the PCI root bridge there are these 2 ACPI Device()s :
> 
>  Scope (_SB.PCI0)
>  {
>      Device (GFX0)
>      {
>          Name (_ADR, 0x00020000)  // _ADR: Address
>      }
> 
>      ...
> 
>      Device (VID)
>      {
>          Name (_ADR, 0x00020000)  // _ADR: Address
>          ...
> 
>          Method (_DOS, 1, NotSerialized)  // _DOS: Disable Output Switching
>          {
>              VDP8 = Arg0
>              VDP1 (One, VDP8)
>          }
> 
>          Method (_DOD, 0, NotSerialized)  // _DOD: Display Output Devices
>          {
>              ...
>          }
>          ...
>      }
>  }
> 
> The non-functional GFX0 ACPI device is a problem, because this gets
> returned as ACPI companion-device by acpi_find_child_device() for the iGPU.
> 
> This is a long standing problem and the i915 driver does use the ACPI
> companion for some things, but works fine without it.
> 
> However since commit 63f534b8bad9 ("ACPI: PCI: Rework acpi_get_pci_dev()")
> acpi_get_pci_dev() relies on the physical-node pointer in the acpi_device
> and that is set on the wrong acpi_device because of the wrong
> acpi_find_child_device() return. This breaks the ACPI video code, leading
> to non working backlight control in some cases.
> 
> Make find_child_checks() return a higher score for children which have
> pnp-ids set by various scan helpers like acpi_is_video_device(), so
> that it picks the right companion-device.
> 
> An alternative approach would be to directly call acpi_is_video_device()
> from find_child_checks() but that would be somewhat computationally
> expensive given that acpi_find_child_device() iterates over all the
> PCI0 children every time it is called.
> 
> Fixes: 63f534b8bad9 ("ACPI: PCI: Rework acpi_get_pci_dev()")
> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
> ---
>  drivers/acpi/glue.c | 14 ++++++++++++--
>  1 file changed, 12 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/acpi/glue.c b/drivers/acpi/glue.c
> index 204fe94c7e45..2055dfd7678b 100644
> --- a/drivers/acpi/glue.c
> +++ b/drivers/acpi/glue.c
> @@ -75,7 +75,7 @@ static struct acpi_bus_type *acpi_get_bus_type(struct device *dev)
>  }
>  
>  #define FIND_CHILD_MIN_SCORE	1
> -#define FIND_CHILD_MAX_SCORE	2
> +#define FIND_CHILD_MAX_SCORE	3
>  
>  static int match_any(struct acpi_device *adev, void *not_used)
>  {
> @@ -89,15 +89,25 @@ static bool acpi_dev_has_children(struct acpi_device *adev)
>  
>  static int find_child_checks(struct acpi_device *adev, bool check_children)
>  {
> +	int score = FIND_CHILD_MIN_SCORE;
>  	unsigned long long sta;
>  	acpi_status status;
>  
>  	if (check_children && !acpi_dev_has_children(adev))
>  		return -ENODEV;
>  
> +	/*
> +	 * For devices without a _STA method, prefer devices without a _HID
> +	 * (which conflicts with having an _ADR) but which have been matched
> +	 * in some other way, like e.g. by acpi_is_video_device() over devices
> +	 * with no ids at all.
> +	 */
> +	if (!adev->pnp.type.platform_id && adev->pnp.type.hardware_id)
> +		score++;
> +
>  	status = acpi_evaluate_integer(adev->handle, "_STA", NULL, &sta);
>  	if (status == AE_NOT_FOUND)
> -		return FIND_CHILD_MIN_SCORE;
> +		return score;
>  
>  	if (ACPI_FAILURE(status) || !(sta & ACPI_STA_DEVICE_ENABLED))
>  		return -ENODEV;

[Intel-gfx] ✗ Fi.CI.BAT: failure for ACPI: Fix selecting the wrong ACPI fwnode for the iGPU on some Dell laptops

[Patchwork]

[-- Attachment #1: Type: text/plain, Size: 10396 bytes --]

== Series Details ==

Series: ACPI: Fix selecting the wrong ACPI fwnode for the iGPU on some Dell laptops
URL   : https://patchwork.freedesktop.org/series/112572/
State : failure

== Summary ==

CI Bug Log - changes from CI_DRM_12560 -> Patchwork_112572v1
====================================================

Summary
-------

  **FAILURE**

  Serious unknown changes coming with Patchwork_112572v1 absolutely need to be
  verified manually.
  
  If you think the reported changes have nothing to do with the changes
  introduced in Patchwork_112572v1, please notify your bug team to allow them
  to document this new failure mode, which will reduce false positives in CI.

  External URL: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_112572v1/index.html

Participating hosts (37 -> 39)
------------------------------

  Additional (3): fi-kbl-soraka fi-rkl-11600 fi-bsw-kefka 
  Missing    (1): fi-snb-2520m 

Possible new issues
-------------------

  Here are the unknown changes that may have been introduced in Patchwork_112572v1:

### IGT changes ###

#### Possible regressions ####

  * igt@i915_selftest@live@guc:
    - fi-kbl-soraka:      NOTRUN -> [INCOMPLETE][1]
   [1]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_112572v1/fi-kbl-soraka/igt@i915_selftest@live@guc.html

  
#### Suppressed ####

  The following results come from untrusted machines, tests, or statuses.
  They do not affect the overall result.

  * igt@gem_exec_suspend@basic-s0@smem:
    - {bat-rpls-1}:       NOTRUN -> [DMESG-WARN][2]
   [2]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_112572v1/bat-rpls-1/igt@gem_exec_suspend@basic-s0@smem.html

  * {igt@kms_chamelium_hpd@common-hpd-after-suspend}:
    - {bat-rpls-2}:       NOTRUN -> [SKIP][3]
   [3]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_112572v1/bat-rpls-2/igt@kms_chamelium_hpd@common-hpd-after-suspend.html

  * {igt@kms_chamelium_hpd@dp-hpd-fast}:
    - fi-rkl-11600:       NOTRUN -> [SKIP][4] +7 similar issues
   [4]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_112572v1/fi-rkl-11600/igt@kms_chamelium_hpd@dp-hpd-fast.html

  
Known issues
------------

  Here are the changes found in Patchwork_112572v1 that come from known issues:

### IGT changes ###

#### Issues hit ####

  * igt@debugfs_test@basic-hwmon:
    - fi-rkl-11600:       NOTRUN -> [SKIP][5] ([i915#7456])
   [5]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_112572v1/fi-rkl-11600/igt@debugfs_test@basic-hwmon.html

  * igt@gem_exec_gttfill@basic:
    - fi-kbl-soraka:      NOTRUN -> [SKIP][6] ([fdo#109271]) +7 similar issues
   [6]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_112572v1/fi-kbl-soraka/igt@gem_exec_gttfill@basic.html

  * igt@gem_huc_copy@huc-copy:
    - fi-rkl-11600:       NOTRUN -> [SKIP][7] ([i915#2190])
   [7]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_112572v1/fi-rkl-11600/igt@gem_huc_copy@huc-copy.html
    - fi-kbl-soraka:      NOTRUN -> [SKIP][8] ([fdo#109271] / [i915#2190])
   [8]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_112572v1/fi-kbl-soraka/igt@gem_huc_copy@huc-copy.html

  * igt@gem_lmem_swapping@basic:
    - fi-kbl-soraka:      NOTRUN -> [SKIP][9] ([fdo#109271] / [i915#4613]) +3 similar issues
   [9]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_112572v1/fi-kbl-soraka/igt@gem_lmem_swapping@basic.html

  * igt@gem_lmem_swapping@parallel-random-engines:
    - fi-rkl-11600:       NOTRUN -> [SKIP][10] ([i915#4613]) +3 similar issues
   [10]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_112572v1/fi-rkl-11600/igt@gem_lmem_swapping@parallel-random-engines.html

  * igt@gem_tiled_pread_basic:
    - fi-rkl-11600:       NOTRUN -> [SKIP][11] ([i915#3282])
   [11]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_112572v1/fi-rkl-11600/igt@gem_tiled_pread_basic.html

  * igt@i915_pm_backlight@basic-brightness:
    - fi-rkl-11600:       NOTRUN -> [SKIP][12] ([i915#7561])
   [12]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_112572v1/fi-rkl-11600/igt@i915_pm_backlight@basic-brightness.html

  * igt@i915_selftest@live@gt_heartbeat:
    - fi-kbl-soraka:      NOTRUN -> [DMESG-FAIL][13] ([i915#5334])
   [13]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_112572v1/fi-kbl-soraka/igt@i915_selftest@live@gt_heartbeat.html
    - fi-apl-guc:         [PASS][14] -> [DMESG-FAIL][15] ([i915#5334])
   [14]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_12560/fi-apl-guc/igt@i915_selftest@live@gt_heartbeat.html
   [15]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_112572v1/fi-apl-guc/igt@i915_selftest@live@gt_heartbeat.html

  * igt@i915_selftest@live@gt_pm:
    - fi-kbl-soraka:      NOTRUN -> [DMESG-FAIL][16] ([i915#1886])
   [16]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_112572v1/fi-kbl-soraka/igt@i915_selftest@live@gt_pm.html

  * igt@i915_suspend@basic-s3-without-i915:
    - fi-rkl-11600:       NOTRUN -> [INCOMPLETE][17] ([i915#4817])
   [17]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_112572v1/fi-rkl-11600/igt@i915_suspend@basic-s3-without-i915.html

  * igt@kms_cursor_legacy@basic-busy-flip-before-cursor:
    - fi-rkl-11600:       NOTRUN -> [SKIP][18] ([i915#4103])
   [18]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_112572v1/fi-rkl-11600/igt@kms_cursor_legacy@basic-busy-flip-before-cursor.html

  * igt@kms_force_connector_basic@force-load-detect:
    - fi-rkl-11600:       NOTRUN -> [SKIP][19] ([fdo#109285] / [i915#4098])
   [19]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_112572v1/fi-rkl-11600/igt@kms_force_connector_basic@force-load-detect.html

  * igt@kms_psr@sprite_plane_onoff:
    - fi-rkl-11600:       NOTRUN -> [SKIP][20] ([i915#1072]) +3 similar issues
   [20]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_112572v1/fi-rkl-11600/igt@kms_psr@sprite_plane_onoff.html

  * igt@kms_setmode@basic-clone-single-crtc:
    - fi-rkl-11600:       NOTRUN -> [SKIP][21] ([i915#3555] / [i915#4098])
   [21]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_112572v1/fi-rkl-11600/igt@kms_setmode@basic-clone-single-crtc.html

  * igt@prime_vgem@basic-fence-flip:
    - fi-bsw-kefka:       NOTRUN -> [SKIP][22] ([fdo#109271]) +17 similar issues
   [22]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_112572v1/fi-bsw-kefka/igt@prime_vgem@basic-fence-flip.html

  * igt@prime_vgem@basic-read:
    - fi-rkl-11600:       NOTRUN -> [SKIP][23] ([fdo#109295] / [i915#3291] / [i915#3708]) +2 similar issues
   [23]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_112572v1/fi-rkl-11600/igt@prime_vgem@basic-read.html

  * igt@prime_vgem@basic-userptr:
    - fi-rkl-11600:       NOTRUN -> [SKIP][24] ([fdo#109295] / [i915#3301] / [i915#3708])
   [24]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_112572v1/fi-rkl-11600/igt@prime_vgem@basic-userptr.html

  
#### Possible fixes ####

  * igt@i915_selftest@live@reset:
    - {bat-rpls-2}:       [DMESG-FAIL][25] ([i915#4983]) -> [PASS][26]
   [25]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_12560/bat-rpls-2/igt@i915_selftest@live@reset.html
   [26]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_112572v1/bat-rpls-2/igt@i915_selftest@live@reset.html
    - {bat-rpls-1}:       [DMESG-FAIL][27] ([i915#4983]) -> [PASS][28]
   [27]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_12560/bat-rpls-1/igt@i915_selftest@live@reset.html
   [28]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_112572v1/bat-rpls-1/igt@i915_selftest@live@reset.html

  * igt@kms_cursor_legacy@basic-busy-flip-before-cursor@atomic-transitions-varying-size:
    - fi-bsw-n3050:       [FAIL][29] ([i915#6298]) -> [PASS][30]
   [29]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_12560/fi-bsw-n3050/igt@kms_cursor_legacy@basic-busy-flip-before-cursor@atomic-transitions-varying-size.html
   [30]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_112572v1/fi-bsw-n3050/igt@kms_cursor_legacy@basic-busy-flip-before-cursor@atomic-transitions-varying-size.html

  
  {name}: This element is suppressed. This means it is ignored when computing
          the status of the difference (SUCCESS, WARNING, or FAILURE).

  [fdo#109271]: https://bugs.freedesktop.org/show_bug.cgi?id=109271
  [fdo#109285]: https://bugs.freedesktop.org/show_bug.cgi?id=109285
  [fdo#109295]: https://bugs.freedesktop.org/show_bug.cgi?id=109295
  [i915#1072]: https://gitlab.freedesktop.org/drm/intel/issues/1072
  [i915#1845]: https://gitlab.freedesktop.org/drm/intel/issues/1845
  [i915#1886]: https://gitlab.freedesktop.org/drm/intel/issues/1886
  [i915#2190]: https://gitlab.freedesktop.org/drm/intel/issues/2190
  [i915#3282]: https://gitlab.freedesktop.org/drm/intel/issues/3282
  [i915#3291]: https://gitlab.freedesktop.org/drm/intel/issues/3291
  [i915#3301]: https://gitlab.freedesktop.org/drm/intel/issues/3301
  [i915#3555]: https://gitlab.freedesktop.org/drm/intel/issues/3555
  [i915#3708]: https://gitlab.freedesktop.org/drm/intel/issues/3708
  [i915#4098]: https://gitlab.freedesktop.org/drm/intel/issues/4098
  [i915#4103]: https://gitlab.freedesktop.org/drm/intel/issues/4103
  [i915#4312]: https://gitlab.freedesktop.org/drm/intel/issues/4312
  [i915#4613]: https://gitlab.freedesktop.org/drm/intel/issues/4613
  [i915#4817]: https://gitlab.freedesktop.org/drm/intel/issues/4817
  [i915#4983]: https://gitlab.freedesktop.org/drm/intel/issues/4983
  [i915#5334]: https://gitlab.freedesktop.org/drm/intel/issues/5334
  [i915#6298]: https://gitlab.freedesktop.org/drm/intel/issues/6298
  [i915#6997]: https://gitlab.freedesktop.org/drm/intel/issues/6997
  [i915#7077]: https://gitlab.freedesktop.org/drm/intel/issues/7077
  [i915#7456]: https://gitlab.freedesktop.org/drm/intel/issues/7456
  [i915#7561]: https://gitlab.freedesktop.org/drm/intel/issues/7561
  [i915#7654]: https://gitlab.freedesktop.org/drm/intel/issues/7654


Build changes
-------------

  * Linux: CI_DRM_12560 -> Patchwork_112572v1

  CI-20190529: 20190529
  CI_DRM_12560: 0eccbe4822259a5e1a78bb7a4c027514d26a2b23 @ git://anongit.freedesktop.org/gfx-ci/linux
  IGT_7113: 15562e123ee6ed88163c7da2ef330dfe9bbd16a5 @ https://gitlab.freedesktop.org/drm/igt-gpu-tools.git
  Patchwork_112572v1: 0eccbe4822259a5e1a78bb7a4c027514d26a2b23 @ git://anongit.freedesktop.org/gfx-ci/linux


### Linux commits

a76273d644d6 ACPI: Fix selecting the wrong ACPI fwnode for the iGPU on some Dell laptops

== Logs ==

For more details see: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_112572v1/index.html

[-- Attachment #2: Type: text/html, Size: 12011 bytes --]

Re: [Intel-gfx] [PATCH] ACPI: Fix selecting the wrong ACPI fwnode for the iGPU on some Dell laptops

[Rafael J. Wysocki]

On Monday, January 9, 2023 9:57:21 PM CET Hans de Goede wrote:
> The Dell Latitude E6430 both with and without the optional NVidia dGPU
> has a bug in its ACPI tables which is causing Linux to assign the wrong
> ACPI fwnode / companion to the pci_device for the i915 iGPU.
> 
> Specifically under the PCI root bridge there are these 2 ACPI Device()s :
> 
>  Scope (_SB.PCI0)
>  {
>      Device (GFX0)
>      {
>          Name (_ADR, 0x00020000)  // _ADR: Address
>      }
> 
>      ...
> 
>      Device (VID)
>      {
>          Name (_ADR, 0x00020000)  // _ADR: Address
>          ...
> 
>          Method (_DOS, 1, NotSerialized)  // _DOS: Disable Output Switching
>          {
>              VDP8 = Arg0
>              VDP1 (One, VDP8)
>          }
> 
>          Method (_DOD, 0, NotSerialized)  // _DOD: Display Output Devices
>          {
>              ...
>          }
>          ...
>      }
>  }
> 
> The non-functional GFX0 ACPI device is a problem, because this gets
> returned as ACPI companion-device by acpi_find_child_device() for the iGPU.
> 
> This is a long standing problem and the i915 driver does use the ACPI
> companion for some things, but works fine without it.
> 
> However since commit 63f534b8bad9 ("ACPI: PCI: Rework acpi_get_pci_dev()")
> acpi_get_pci_dev() relies on the physical-node pointer in the acpi_device
> and that is set on the wrong acpi_device because of the wrong
> acpi_find_child_device() return. This breaks the ACPI video code, leading
> to non working backlight control in some cases.

Interesting.  Sorry for the trouble.

> Make find_child_checks() return a higher score for children which have
> pnp-ids set by various scan helpers like acpi_is_video_device(), so
> that it picks the right companion-device.

This has a potential of changing the behavior in some cases that are not
relevant here which is generally risky.

> An alternative approach would be to directly call acpi_is_video_device()
> from find_child_checks() but that would be somewhat computationally
> expensive given that acpi_find_child_device() iterates over all the
> PCI0 children every time it is called.

I agree with the above, but my fix would be something like the patch below (not
really tested, but it builds).

---
 drivers/acpi/glue.c     |   14 ++++++++++++--
 drivers/acpi/scan.c     |    7 +++++--
 include/acpi/acpi_bus.h |    3 ++-
 3 files changed, 19 insertions(+), 5 deletions(-)

Index: linux-pm/include/acpi/acpi_bus.h
===================================================================
--- linux-pm.orig/include/acpi/acpi_bus.h
+++ linux-pm/include/acpi/acpi_bus.h
@@ -230,7 +230,8 @@ struct acpi_pnp_type {
 	u32 hardware_id:1;
 	u32 bus_address:1;
 	u32 platform_id:1;
-	u32 reserved:29;
+	u32 backlight:1;
+	u32 reserved:28;
 };
 
 struct acpi_device_pnp {
Index: linux-pm/drivers/acpi/scan.c
===================================================================
--- linux-pm.orig/drivers/acpi/scan.c
+++ linux-pm/drivers/acpi/scan.c
@@ -1370,9 +1370,12 @@ static void acpi_set_pnp_ids(acpi_handle
 		 * Some devices don't reliably have _HIDs & _CIDs, so add
 		 * synthetic HIDs to make sure drivers can find them.
 		 */
-		if (acpi_is_video_device(handle))
+		if (acpi_is_video_device(handle)) {
 			acpi_add_id(pnp, ACPI_VIDEO_HID);
-		else if (acpi_bay_match(handle))
+			pnp->type.backlight = 1;
+			break;
+		}
+		if (acpi_bay_match(handle))
 			acpi_add_id(pnp, ACPI_BAY_HID);
 		else if (acpi_dock_match(handle))
 			acpi_add_id(pnp, ACPI_DOCK_HID);
Index: linux-pm/drivers/acpi/glue.c
===================================================================
--- linux-pm.orig/drivers/acpi/glue.c
+++ linux-pm/drivers/acpi/glue.c
@@ -75,7 +75,8 @@ static struct acpi_bus_type *acpi_get_bu
 }
 
 #define FIND_CHILD_MIN_SCORE	1
-#define FIND_CHILD_MAX_SCORE	2
+#define FIND_CHILD_MID_SCORE	2
+#define FIND_CHILD_MAX_SCORE	3
 
 static int match_any(struct acpi_device *adev, void *not_used)
 {
@@ -96,8 +97,17 @@ static int find_child_checks(struct acpi
 		return -ENODEV;
 
 	status = acpi_evaluate_integer(adev->handle, "_STA", NULL, &sta);
-	if (status == AE_NOT_FOUND)
+	if (status == AE_NOT_FOUND) {
+		/*
+		 * Special case: backlight device objects without _STA are
+		 * preferred to other objects with the same _ADR value, because
+		 * it is more likely that they are actually useful.
+		 */
+		if (adev->pnp.type.backlight)
+			return FIND_CHILD_MID_SCORE;
+
 		return FIND_CHILD_MIN_SCORE;
+	}
 
 	if (ACPI_FAILURE(status) || !(sta & ACPI_STA_DEVICE_ENABLED))
 		return -ENODEV;

Re: [Intel-gfx] [PATCH] ACPI: Fix selecting the wrong ACPI fwnode for the iGPU on some Dell laptops

[Hans de Goede]

Hi Rafael,

On 1/10/23 14:33, Rafael J. Wysocki wrote:
> On Monday, January 9, 2023 9:57:21 PM CET Hans de Goede wrote:
>> The Dell Latitude E6430 both with and without the optional NVidia dGPU
>> has a bug in its ACPI tables which is causing Linux to assign the wrong
>> ACPI fwnode / companion to the pci_device for the i915 iGPU.
>>
>> Specifically under the PCI root bridge there are these 2 ACPI Device()s :
>>
>>  Scope (_SB.PCI0)
>>  {
>>      Device (GFX0)
>>      {
>>          Name (_ADR, 0x00020000)  // _ADR: Address
>>      }
>>
>>      ...
>>
>>      Device (VID)
>>      {
>>          Name (_ADR, 0x00020000)  // _ADR: Address
>>          ...
>>
>>          Method (_DOS, 1, NotSerialized)  // _DOS: Disable Output Switching
>>          {
>>              VDP8 = Arg0
>>              VDP1 (One, VDP8)
>>          }
>>
>>          Method (_DOD, 0, NotSerialized)  // _DOD: Display Output Devices
>>          {
>>              ...
>>          }
>>          ...
>>      }
>>  }
>>
>> The non-functional GFX0 ACPI device is a problem, because this gets
>> returned as ACPI companion-device by acpi_find_child_device() for the iGPU.
>>
>> This is a long standing problem and the i915 driver does use the ACPI
>> companion for some things, but works fine without it.
>>
>> However since commit 63f534b8bad9 ("ACPI: PCI: Rework acpi_get_pci_dev()")
>> acpi_get_pci_dev() relies on the physical-node pointer in the acpi_device
>> and that is set on the wrong acpi_device because of the wrong
>> acpi_find_child_device() return. This breaks the ACPI video code, leading
>> to non working backlight control in some cases.
> 
> Interesting.  Sorry for the trouble.

No problem, as mentioned this is actually a long standing issue / bug
in the ACPI tables, it just never surfaced before.

>> Make find_child_checks() return a higher score for children which have
>> pnp-ids set by various scan helpers like acpi_is_video_device(), so
>> that it picks the right companion-device.
> 
> This has a potential of changing the behavior in some cases that are not
> relevant here which is generally risky.
> 
>> An alternative approach would be to directly call acpi_is_video_device()
>> from find_child_checks() but that would be somewhat computationally
>> expensive given that acpi_find_child_device() iterates over all the
>> PCI0 children every time it is called.
> 
> I agree with the above, but my fix would be something like the patch below (not
> really tested, but it builds).

Thanks, I have just given this a spin on my E6430 and I can confirm
it still fixes things.

I'll send out this version (re-using most of the v1 commitmsg) as a v2
right away.

Regards,

Hans





> 
> ---
>  drivers/acpi/glue.c     |   14 ++++++++++++--
>  drivers/acpi/scan.c     |    7 +++++--
>  include/acpi/acpi_bus.h |    3 ++-
>  3 files changed, 19 insertions(+), 5 deletions(-)
> 
> Index: linux-pm/include/acpi/acpi_bus.h
> ===================================================================
> --- linux-pm.orig/include/acpi/acpi_bus.h
> +++ linux-pm/include/acpi/acpi_bus.h
> @@ -230,7 +230,8 @@ struct acpi_pnp_type {
>  	u32 hardware_id:1;
>  	u32 bus_address:1;
>  	u32 platform_id:1;
> -	u32 reserved:29;
> +	u32 backlight:1;
> +	u32 reserved:28;
>  };
>  
>  struct acpi_device_pnp {
> Index: linux-pm/drivers/acpi/scan.c
> ===================================================================
> --- linux-pm.orig/drivers/acpi/scan.c
> +++ linux-pm/drivers/acpi/scan.c
> @@ -1370,9 +1370,12 @@ static void acpi_set_pnp_ids(acpi_handle
>  		 * Some devices don't reliably have _HIDs & _CIDs, so add
>  		 * synthetic HIDs to make sure drivers can find them.
>  		 */
> -		if (acpi_is_video_device(handle))
> +		if (acpi_is_video_device(handle)) {
>  			acpi_add_id(pnp, ACPI_VIDEO_HID);
> -		else if (acpi_bay_match(handle))
> +			pnp->type.backlight = 1;
> +			break;
> +		}
> +		if (acpi_bay_match(handle))
>  			acpi_add_id(pnp, ACPI_BAY_HID);
>  		else if (acpi_dock_match(handle))
>  			acpi_add_id(pnp, ACPI_DOCK_HID);
> Index: linux-pm/drivers/acpi/glue.c
> ===================================================================
> --- linux-pm.orig/drivers/acpi/glue.c
> +++ linux-pm/drivers/acpi/glue.c
> @@ -75,7 +75,8 @@ static struct acpi_bus_type *acpi_get_bu
>  }
>  
>  #define FIND_CHILD_MIN_SCORE	1
> -#define FIND_CHILD_MAX_SCORE	2
> +#define FIND_CHILD_MID_SCORE	2
> +#define FIND_CHILD_MAX_SCORE	3
>  
>  static int match_any(struct acpi_device *adev, void *not_used)
>  {
> @@ -96,8 +97,17 @@ static int find_child_checks(struct acpi
>  		return -ENODEV;
>  
>  	status = acpi_evaluate_integer(adev->handle, "_STA", NULL, &sta);
> -	if (status == AE_NOT_FOUND)
> +	if (status == AE_NOT_FOUND) {
> +		/*
> +		 * Special case: backlight device objects without _STA are
> +		 * preferred to other objects with the same _ADR value, because
> +		 * it is more likely that they are actually useful.
> +		 */
> +		if (adev->pnp.type.backlight)
> +			return FIND_CHILD_MID_SCORE;
> +
>  		return FIND_CHILD_MIN_SCORE;
> +	}
>  
>  	if (ACPI_FAILURE(status) || !(sta & ACPI_STA_DEVICE_ENABLED))
>  		return -ENODEV;
> 
> 
>