Hi Pankaj, > -----Original Message----- > From: linux-arm-kernel <linux-arm-kernel-boun...@lists.infradead.org> On > Behalf Of Pankaj Bansal > Sent: Friday, May 10, 2019 3:34 PM > > Hi Will/Robin/Joerg, > > I am s/w engineer from NXP India Pvt. Ltd. > We are using SMMU-V3 in one of NXP SOC. > I have a question about the SMMU Stream ID allocation in linux. > > Right now the Stream IDs allocated to a device are mapped via device tree > to the device.
[snip] > > As the device tree is passed from bootloader to linux, we detect all the > stream IDs needed by a device in bootloader and add their IDs in > respective device nodes. > For each PCIE Endpoint (a unique BDF (Bus Device Function)) on PCIE bus, > we are assigning a unique Stream ID in bootloader. > > However, this poses an issue with PCIE hot plug. > If we plug in a pcie device while linux is running, a unique BDF is > assigned to the device, for which there is no stream ID in device tree. > > How can this problem be solved in linux? > > Is there a way to assign (and revoke) stream IDs at run time? I think that our main problem is that we enumerate the PCI EPs in the bootloader (u-boot) and allocate StreamIDs just for them, completely disregarding hotplug scenarios. One simple fix would be to not do this and simply allocate a decently sized, fixed range of StreamIDs per PCI controller. --- Best Regards, Laurentiu _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
