Re: [PATCH] ACPI: Fix selecting the wrong ACPI fwnode for the iGPU on some Dell laptops
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, 0x0002) // _ADR: Address
>> }
>>
>> ...
>>
>> Device (VID)
>> {
>> Name (_ADR, 0x0002) // _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, );
> - if (status == AE_NOT_FOUND)
> + if (status == AE_NOT_FOUND) {
> + /*
> + * Special case:
Re: [PATCH] ACPI: Fix selecting the wrong ACPI fwnode for the iGPU on some Dell laptops
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, 0x0002) // _ADR: Address
> }
>
> ...
>
> Device (VID)
> {
> Name (_ADR, 0x0002) // _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, );
- 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: [PATCH] ACPI: Fix selecting the wrong ACPI fwnode for the iGPU on some Dell laptops
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, 0x0002) // _ADR: Address
> }
>
> ...
>
> Device (VID)
> {
> Name (_ADR, 0x0002) // _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
> ---
> 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, );
> if (status == AE_NOT_FOUND)
> - return FIND_CHILD_MIN_SCORE;
> + return score;
>
> if (ACPI_FAILURE(status) || !(sta & ACPI_STA_DEVICE_ENABLED))
> return -ENODEV;
[PATCH] ACPI: Fix selecting the wrong ACPI fwnode for the iGPU on some Dell laptops
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, 0x0002) // _ADR: Address
}
...
Device (VID)
{
Name (_ADR, 0x0002) // _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
---
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, );
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
