Re: [PATCH] media: staging: ipu3: Enable IOVA API only when IOMMU support is enabled

From: Robin Murphy <robin.murphy@arm.com>
To: Sakari Ailus <sakari.ailus@linux.intel.com>,
	YueHaibing <yuehaibing@huawei.com>
Cc: devel@driverdev.osuosl.org, gregkh@linuxfoundation.org,
	linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org,
	yong.zhi@intel.com, hverkuil-cisco@xs4all.nl, digetx@gmail.com,
	mchehab@kernel.org, linux-media@vger.kernel.org
Subject: Re: [PATCH] media: staging: ipu3: Enable IOVA API only when IOMMU support is enabled
Date: Wed, 24 Jul 2019 14:49:41 +0100	[thread overview]
Message-ID: <e48fc180-06cc-eac7-d8ca-9be1699c8677@arm.com> (raw)
In-Reply-To: <20190724103027.GD21370@paasikivi.fi.intel.com>

On 24/07/2019 11:30, Sakari Ailus wrote:
> Hi Yue,
> 
> On Mon, Jul 22, 2019 at 09:47:49PM +0800, YueHaibing wrote:
>> If IOMMU_SUPPORT is not set, ipu3 driver may select IOMMU_IOVA to m.
>> But for many drivers, they use "select IOMMU_IOVA if IOMMU_SUPPORT"
>> in the Kconfig, for example, CONFIG_TEGRA_VDE is set to y but IOMMU_IOVA
>> is m, then the building fails like this:
>>
>> drivers/staging/media/tegra-vde/iommu.o: In function `tegra_vde_iommu_map':
>> iommu.c:(.text+0x41): undefined reference to `alloc_iova'
>> iommu.c:(.text+0x56): undefined reference to `__free_iova'
>>
>> Reported-by: Hulk Robot <hulkci@huawei.com>
>> Fixes: 7fc7af649ca7 ("media: staging/intel-ipu3: Add imgu top level pci device driver")
>> Signed-off-by: YueHaibing <yuehaibing@huawei.com>
>> ---
>>   drivers/staging/media/ipu3/Kconfig | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/staging/media/ipu3/Kconfig b/drivers/staging/media/ipu3/Kconfig
>> index 4b51c67..b7df18f 100644
>> --- a/drivers/staging/media/ipu3/Kconfig
>> +++ b/drivers/staging/media/ipu3/Kconfig
>> @@ -4,7 +4,7 @@ config VIDEO_IPU3_IMGU
>>   	depends on PCI && VIDEO_V4L2
>>   	depends on MEDIA_CONTROLLER && VIDEO_V4L2_SUBDEV_API
>>   	depends on X86
>> -	select IOMMU_IOVA
>> +	select IOMMU_IOVA if IOMMU_SUPPORT
> 
> This doesn't seem right: the ipu3-cio2 driver needs IOMMU_IOVA
> independently of IOMMU_SUPPORT.
> 
> Looking at tegra-vde, it seems to depend on IOMMU_SUPPORT but that's not
> declared in its Kconfig entry. I wonder if adding that would be the right
> way to fix this.
> 
> Cc'ing the IOMMU list.

Right, I also had the impression that we'd made the IOVA library 
completely standalone. And what does the IPU3 driver's Kconfig have to 
do with some *other* driver failing to link anyway?

Robin.

> 
>>   	select VIDEOBUF2_DMA_SG
>>   	help
>>   	  This is the Video4Linux2 driver for Intel IPU3 image processing unit,
> 
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