[PATCH] AMD_SFH: Add a DMI quirk entry for Chromebooks

[PATCH] AMD_SFH: Add a DMI quirk entry for Chromebooks

[Akihiko Odaki]

Google Chromebooks use Chrome OS Embedded Controller Sensor Hub instead
of Sensor Hub Fusion and leaves MP2 uninitialized, which disables all
functionalities, even including the registers necessary for feature
detections.

The behavior was observed with Lenovo ThinkPad C13 Yoga.

Signed-off-by: Akihiko Odaki <akihiko.odaki@gmail.com>
---
 drivers/hid/amd-sfh-hid/amd_sfh_pcie.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/hid/amd-sfh-hid/amd_sfh_pcie.c b/drivers/hid/amd-sfh-hid/amd_sfh_pcie.c
index dadc491bbf6b..b91e1c95e543 100644
--- a/drivers/hid/amd-sfh-hid/amd_sfh_pcie.c
+++ b/drivers/hid/amd-sfh-hid/amd_sfh_pcie.c
@@ -197,6 +197,18 @@ static const struct dmi_system_id dmi_sensor_mask_overrides[] = {
 		},
 		.driver_data = (void *)(ACEL_EN | MAGNO_EN),
 	},
+	{
+		/*
+		 * Google Chromebooks use Chrome OS Embedded Controller Sensor
+		 * Hub instead of Sensor Hub Fusion and leaves MP2
+		 * uninitialized, which disables all functionalities, even
+		 * including the registers necessary for feature detections.
+		 */
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "Google"),
+		},
+		.driver_data = (void *)0,
+	},
 	{ }
 };
 
-- 
2.36.1

Re: [PATCH] AMD_SFH: Add a DMI quirk entry for Chromebooks

[Mario Limonciello]

On 7/10/22 03:15, Akihiko Odaki wrote:
> Google Chromebooks use Chrome OS Embedded Controller Sensor Hub instead
> of Sensor Hub Fusion and leaves MP2 uninitialized, which disables all
> functionalities, even including the registers necessary for feature
> detections.
> 
> The behavior was observed with Lenovo ThinkPad C13 Yoga.
> 

You missed that I suggested this from your earlier patch, you should add:

Suggested-by: Mario Limonciello <mario.limonciello@amd.com>

> Signed-off-by: Akihiko Odaki <akihiko.odaki@gmail.com>
> ---
>   drivers/hid/amd-sfh-hid/amd_sfh_pcie.c | 12 ++++++++++++
>   1 file changed, 12 insertions(+)
> 
> diff --git a/drivers/hid/amd-sfh-hid/amd_sfh_pcie.c b/drivers/hid/amd-sfh-hid/amd_sfh_pcie.c
> index dadc491bbf6b..b91e1c95e543 100644
> --- a/drivers/hid/amd-sfh-hid/amd_sfh_pcie.c
> +++ b/drivers/hid/amd-sfh-hid/amd_sfh_pcie.c
> @@ -197,6 +197,18 @@ static const struct dmi_system_id dmi_sensor_mask_overrides[] = {
>   		},
>   		.driver_data = (void *)(ACEL_EN | MAGNO_EN),
>   	},
> +	{
> +		/*
> +		 * Google Chromebooks use Chrome OS Embedded Controller Sensor
> +		 * Hub instead of Sensor Hub Fusion and leaves MP2
> +		 * uninitialized, which disables all functionalities, even
> +		 * including the registers necessary for feature detections.
> +		 */
> +		.matches = {
> +			DMI_MATCH(DMI_SYS_VENDOR, "Google"),
> +		},
> +		.driver_data = (void *)0,
> +	},
>   	{ }
>   };
>   

Is this enough actually?  I would think you need to also modify 
amd_sfh_hid_client_init to special case the situation of "no sensors" 
and return -ENODEV otherwise it's going to try to read discovery status 
too and that might not be safe and deterministic.