Messages in this thread | | | Subject | Re: [PATCH 3/3] iommu: armsmmu: set iommu ops for rpmsg bus | From | Robin Murphy <> | Date | Fri, 2 Mar 2018 16:59:12 +0000 |
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On 02/03/18 14:55, srinivas.kandagatla@linaro.org wrote: > From: Srinivas Kandagatla <srinivas.kandagatla@linaro.org> > > On Qualcomm SoCs, ADSP exposes many functions like audio and > others. These services need iommu access to allocate any > memory for the DSP. As these drivers are childeren of > rpmsg bus, able to allocate memory from iommus is basic > requirement. So set arm smmu iommu ops for this bus type.
Documentation/rpmsg.txt: "Every rpmsg device is a communication channel with a remote processor (thus rpmsg devices are called channels)."
I'd instinctively assume that a remote processor already has its own memory, and that a communication channel doesn't somehow go directly through an IOMMU, so that "basic requirement" seems like a pretty big assumption.
> Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org> > --- > drivers/iommu/arm-smmu.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c > index e6920d32ac9e..9b63489af15c 100644 > --- a/drivers/iommu/arm-smmu.c > +++ b/drivers/iommu/arm-smmu.c > @@ -53,6 +53,7 @@ > #include <linux/spinlock.h> > > #include <linux/amba/bus.h> > +#include <linux/rpmsg.h> > > #include "io-pgtable.h" > #include "arm-smmu-regs.h" > @@ -2168,6 +2169,10 @@ static void arm_smmu_bus_init(void) > bus_set_iommu(&pci_bus_type, &arm_smmu_ops); > } > #endif > +#ifdef CONFIG_RPMSG
Ah, so this will at least build OK with RPMSG=m, but I doubt it does what you want it to in that case.
Robin.
> + if (!iommu_present(&rpmsg_bus)) > + bus_set_iommu(&rpmsg_bus, &arm_smmu_ops); > +#endif > } > > static int arm_smmu_device_probe(struct platform_device *pdev) >
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