Messages in this thread | | | Subject | Re: [PATCH] media: staging: ipu3: Enable IOVA API only when IOMMU support is enabled | From | Robin Murphy <> | Date | Wed, 24 Jul 2019 15:23:55 +0100 |
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On 24/07/2019 15:09, Dmitry Osipenko wrote: > 24.07.2019 17:03, Yuehaibing пишет: >> On 2019/7/24 21:49, Robin Murphy wrote: >>> 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. > IOMMU_SUPPORT is optional for the Tegra-VDE driver. > >>> 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? > > I can see it failing if IPU3 is compiled as a loadable module, while > Tegra-VDE is a built-in driver. Hence IOVA lib should be also a kernel > module and thus the IOVA symbols will be missing during of linkage of > the VDE driver. > >> Oh, I misunderstand that IOMMU_IOVA is depend on IOMMU_SUPPORT, thank you for clarification. >> >> I will try to fix this in tegra-vde. > > Probably IOVA could be selected independently of IOMMU_SUPPORT, but IOVA > library isn't needed for the VDE driver if IOMMU_SUPPORT is disabled.
Oh, I think I get the problem now - tegra-vde/iommu.c is built unconditionally and relies on the static inline stubs for IOMMU and IOVA calls if !IOMMU_SUPPORT, but in a compile-test config where IOVA=m for other reasons, it then picks up the real declarations from linux/iova.h instead of the stubs, and things go downhill from there. So there is a real issue, but indeed it's Tegra-VDE which needs to be restructured to cope with such configurations, and not IPU3's (or anyone else who may select IOVA=m in future) job to work around it.
Robin.
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