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

[Robin Murphy]

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@xxxxxxxxxx>
> > Fixes: 7fc7af649ca7 ("media: staging/intel-ipu3: Add imgu top level pci device driver")
> > Signed-off-by: YueHaibing <yuehaibing@xxxxxxxxxx>
> > ---
> >   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,