linux-kernel - Re: [PATCH V5 5/6] vfio: platform: call

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Message-ID: <5743BB1E.10607@codeaurora.org>
Date:	Mon, 23 May 2016 22:23:26 -0400
From:	Sinan Kaya <okaya@...eaurora.org>
To:	Eric Auger <eric.auger@...aro.org>, kvm@...r.kernel.org,
	timur@...eaurora.org, cov@...eaurora.org, jcm@...hat.com
Cc:	linux-acpi@...r.kernel.org, agross@...eaurora.org,
	linux-arm-msm@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	Baptiste Reynal <b.reynal@...tualopensystems.com>,
	Alex Williamson <alex.williamson@...hat.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH V5 5/6] vfio: platform: call _RST method when using ACPI

On 5/23/2016 10:41 AM, Eric Auger wrote:
> On 05/16/2016 04:13 AM, Sinan Kaya wrote:
>> The device tree code checks for the presence of a reset driver and calls
>> the of_reset function pointer by looking up the reset driver as a module.
>>
>> ACPI defines _RST method to perform device level reset. After the _RST
>> method is executed, the OS can resume using the device.
>>
>> This patch checks the presence of _RST method and calls the _RST
>> method when reset is requested.
>>
>> Signed-off-by: Sinan Kaya <okaya@...eaurora.org>
>> ---
>>  drivers/vfio/platform/vfio_platform_common.c | 44 ++++++++++++++++++++++++++++
>>  1 file changed, 44 insertions(+)
>>
>> diff --git a/drivers/vfio/platform/vfio_platform_common.c b/drivers/vfio/platform/vfio_platform_common.c
>> index d859d3b..095d5b7 100644
>> --- a/drivers/vfio/platform/vfio_platform_common.c
>> +++ b/drivers/vfio/platform/vfio_platform_common.c
>> @@ -73,21 +73,59 @@ int vfio_platform_acpi_probe(struct vfio_platform_device *vdev,
>>  	}
>>  	return 0;
>>  }
>> +
>> +static int vfio_platform_acpi_call_reset(struct vfio_platform_device *vdev)
>> +{
>> +	struct device *dev = vdev->device;
>> +	acpi_handle handle = ACPI_HANDLE(dev);
>> +	acpi_status acpi_ret;
>> +	unsigned long long val;
>> +
>> +	acpi_ret = acpi_evaluate_integer(handle, "_RST", NULL, &val);
>> +	if (ACPI_FAILURE(acpi_ret))
>> +		return -EINVAL;
>> +
>> +	return 0;
>> +}
>> +
>> +static bool vfio_platform_acpi_has_reset(struct vfio_platform_device *vdev)
>> +{
>> +	struct device *dev = vdev->device;
>> +	acpi_handle handle = ACPI_HANDLE(dev);
>> +
>> +	return acpi_has_method(handle, "_RST");
>> +}
>>  #else
>>  int vfio_platform_acpi_probe(struct vfio_platform_device *vdev,
>>  			     struct device *dev)
>>  {
>>  	return -EINVAL;
>>  }
>> +
>> +static int vfio_platform_acpi_call_reset(struct vfio_platform_device *vdev)
>> +{
> nit: inline
>> +	return -EINVAL;
>> +}
>> +
>> +static bool vfio_platform_acpi_has_reset(struct vfio_platform_device *vdev)
> nit: inline

sure

> 
> Besides Reviewed-by: Eric Auger <eric.auger@...aro.org>
>

thanks
 
> It is not explictly written in the ACPI spec that _RST is expected to
> stop DMA transfers and IRQs although this may be implicit in the notion
> of "function level reset ". May be worth adding this info in the commit msg?
> 

yes, I'll add DMA and IRQ requirement to the commit message.

> Best Regards
> 
> Eric
>> +{
>> +	return false;
>> +}
>>  #endif
>>  
>>  static bool vfio_platform_has_reset(struct vfio_platform_device *vdev)
>>  {
>> +	if (vdev->acpihid)
>> +		return vfio_platform_acpi_has_reset(vdev);
>> +
>>  	return vdev->of_reset ? true : false;
>>  }
>>  
>>  static void vfio_platform_get_reset(struct vfio_platform_device *vdev)
>>  {
>> +	if (vdev->acpihid)
>> +		return;
>> +
>>  	vdev->of_reset = vfio_platform_lookup_reset(vdev->compat,
>>  						    &vdev->reset_module);
>>  	if (!vdev->of_reset) {
>> @@ -99,6 +137,9 @@ static void vfio_platform_get_reset(struct vfio_platform_device *vdev)
>>  
>>  static void vfio_platform_put_reset(struct vfio_platform_device *vdev)
>>  {
>> +	if (vdev->acpihid)
>> +		return;
>> +
>>  	if (vdev->of_reset)
>>  		module_put(vdev->reset_module);
>>  }
>> @@ -177,6 +218,9 @@ static int vfio_platform_call_reset(struct vfio_platform_device *vdev)
>>  		dev_info(vdev->device, "reset\n");
>>  		vdev->of_reset(vdev);
>>  		return 0;
>> +	} else if (vdev->acpihid) {
>> +		dev_info(vdev->device, "reset\n");
>> +		return vfio_platform_acpi_call_reset(vdev);
>>  	}
>>  
>>  	dev_warn(vdev->device, "no reset function found!\n");
>>
> 


-- 
Sinan Kaya
Qualcomm Technologies, Inc. on behalf of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project