linux-kernel - Re: [PATCH v1 5/7] surface: surface3_power: Use ACPI

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Date:   Tue, 12 Oct 2021 20:21:37 +0200
From:   Maximilian Luz <luzmaximilian@...il.com>
To:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Linux ACPI <linux-acpi@...r.kernel.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Hans de Goede <hdegoede@...hat.com>,
        Mark Gross <mgross@...ux.intel.com>,
        platform-driver-x86@...r.kernel.org
Subject: Re: [PATCH v1 5/7] surface: surface3_power: Use ACPI_COMPANION()
 directly

On 10/12/21 19:46, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael@...nel.org>
> 
> The ACPI_HANDLE() macro is a wrapper arond the ACPI_COMPANION()
> macro and the ACPI handle produced by the former comes from the
> ACPI device object produced by the latter, so it is way more
> straightforward to evaluate the latter directly instead of passing
> the handle produced by the former to acpi_bus_get_device().
> 
> Modify mshw0011_notify() accordingly (no intentional functional
> impact).
> 
> Signed-off-by: Rafael J. Wysocki <rafael@...nel.org>

Looks mostly good to me, small comment/question inline.

> ---
>   drivers/platform/surface/surface3_power.c |    9 ++++-----
>   1 file changed, 4 insertions(+), 5 deletions(-)
> 
> Index: linux-pm/drivers/platform/surface/surface3_power.c
> ===================================================================
> --- linux-pm.orig/drivers/platform/surface/surface3_power.c
> +++ linux-pm/drivers/platform/surface/surface3_power.c
> @@ -160,15 +160,14 @@ mshw0011_notify(struct mshw0011_data *cd
>   {
>   	union acpi_object *obj;
>   	struct acpi_device *adev;
> -	acpi_handle handle;
>   	unsigned int i;
>   
> -	handle = ACPI_HANDLE(&cdata->adp1->dev);
> -	if (!handle || acpi_bus_get_device(handle, &adev))
> +	adev = ACPI_COMPANION(&cdata->adp1->dev);
> +	if (!adev)
>   		return -ENODEV;

Do we need to get the ACPI device (adev) here? To me it looks like only
its handle is actually used so why not keep ACPI_HANDLE() and remove the
acpi_bus_get_device() call instead?

>   
> -	obj = acpi_evaluate_dsm_typed(handle, &mshw0011_guid, arg1, arg2, NULL,
> -				      ACPI_TYPE_BUFFER);
> +	obj = acpi_evaluate_dsm_typed(adev->handle, &mshw0011_guid, arg1, arg2,
> +				      NULL, ACPI_TYPE_BUFFER);
>   	if (!obj) {
>   		dev_err(&cdata->adp1->dev, "device _DSM execution failed\n");
>   		return -ENODEV;
> 
> 
> 

Regards,
Max