linux-kernel - Re: [PATCH] drivers: mfd: check ACPI device companion before checking resources

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Date:	Wed, 13 May 2015 15:42:43 +0100
From:	Lee Jones <lee.jones@...aro.org>
To:	Lorenzo Pieralisi <lorenzo.pieralisi@....com>
Cc:	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	Sudeep Holla <sudeep.holla@....com>,
	Samuel Ortiz <sameo@...ux.intel.com>
Subject: Re: [PATCH] drivers: mfd: check ACPI device companion before
 checking resources

On Fri, 01 May 2015, Lorenzo Pieralisi wrote:

> Current code in mfd-core calls into ACPI to check resources even
> on a system that booted with a DT (on kernels with both DT and ACPI
> support compiled in). This triggers ACPI exceptions since we may
> end up calling the ACPI interpreter when it has not been initialized:
> 
> "ACPI Exception: AE_BAD_PARAMETER, Thread 2064154624 could not acquire
> Mutex [0x1] (20150410/utmutex-285)"
> 
> This patch fixes the issues by adding a check for an ACPI companion
> device before carrying out ACPI resources checks to avoid calling
> the ACPI interpreter if the fwnode representing the device is an OF one.
> 
> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
> Cc: Sudeep Holla <sudeep.holla@....com>
> Cc: Lee Jones <lee.jones@...aro.org>
> Cc: Samuel Ortiz <sameo@...ux.intel.com>
> ---
> Lee, Samuel,
> 
> I could not test it on X86 and I do not know if you prefer setting
> ignore_resource_conflicts in the respective mfd cells (ie vexpress),
> just let me know how do you want to fix it.

Patch looks fine to me.  It doesn't change current *expected*
behaviour and adds extra protection against the aforementioned issue.

Applied, thanks.

>  drivers/mfd/mfd-core.c | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/mfd/mfd-core.c b/drivers/mfd/mfd-core.c
> index 1aed3b7..14fd5cb 100644
> --- a/drivers/mfd/mfd-core.c
> +++ b/drivers/mfd/mfd-core.c
> @@ -207,9 +207,11 @@ static int mfd_add_device(struct device *parent, int id,
>  		}
>  
>  		if (!cell->ignore_resource_conflicts) {
> -			ret = acpi_check_resource_conflict(&res[r]);
> -			if (ret)
> -				goto fail_alias;
> +			if (has_acpi_companion(&pdev->dev)) {
> +				ret = acpi_check_resource_conflict(&res[r]);
> +				if (ret)
> +					goto fail_alias;
> +			}
>  		}
>  	}
>  

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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