linux-kernel - Re: [PATCH] ACPI: scan: Ignore MAGN0001

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Message-ID: <06e9623d-26ae-e0e3-8fd8-1f5c89497a5a@redhat.com>
Date:   Fri, 21 Apr 2023 20:07:20 +0200
From:   Hans de Goede <hdegoede@...hat.com>
To:     Marius Hoch <mail@...iushoch.de>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Len Brown <lenb@...nel.org>, linux-acpi@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ACPI: scan: Ignore MAGN0001

Hi Marius,

On 4/21/23 18:27, Marius Hoch wrote:
> The LSM303D on the Lenovo Yoga Tablet 2 series is present
> as both ACCL0001 and MAGN0001. As we can only ever register an
> i2c client for one of them, ignore MAGN0001.
> 
> Currently this errors:
> i2c i2c-4: Failed to register i2c client MAGN0001:00 at 0x1d (-16)
> 
> Tested on a Lenovo Yoga Tablet 2 1051-F.
> 
> Signed-off-by: Marius Hoch <mail@...iushoch.de>

By adding the HID to the ignore_serial_bus_ids[] list, you are
causing the ACPI code to instead instantiate a platform_device
for it.

This will successfully silence the error you are trying to silence,
but I don't think it really is what you intent / want to do ?

IMHO it would be better to add a NOT_PRESENT_ENTRY_HID() entry
to the override_status_ids[] table in drivers/acpi/x86/utils.c,
this will override the return of _STA, causing neither a
platform_device not an i2c_client to get instantiated for
the duplicate MAGN0001 device.

(please keep the comment above the entry why the entry is there)

Regards,

Hans







> ---
>  drivers/acpi/scan.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
> index 0c6f06abe3f4..d21c411e9719 100644
> --- a/drivers/acpi/scan.c
> +++ b/drivers/acpi/scan.c
> @@ -1730,6 +1730,12 @@ static bool acpi_device_enumeration_by_parent(struct acpi_device *device)
>  	 */
>  		{"BCM4752", },
>  		{"LNV4752", },
> +	/*
> +	 * The LSM303D on the Lenovo Yoga Tablet 2 series is present
> +	 * as both ACCL0001 and MAGN0001. As we can only ever register an
> +	 * i2c client for one of them, ignore MAGN0001.
> +	 */
> +		{"MAGN0001", },
>  		{}
>  	};
>  
> 
> base-commit: cb0856346a60fe3eb837ba5e73588a41f81ac05f