On Fri, Feb 26, 2021 at 06:53:52AM +0100, Christoph Hellwig wrote: > On Thu, Feb 25, 2021 at 11:35:57AM -0500, Alan Stern wrote: > > This thread seems to have fallen through the cracks. Maybe now would be > > a good time to address the problem (since we originally planned to fix > > it in 5.11!). > > > > The questions listed below are pretty self-contained, although the rest > > of the discussion isn't. But I never received any answers. > > usb-storage must use scsi_add_host_with_dma to use the right device > for DMA mapping and parameters. The calls to set the DMA options > on the device are needed so that IOMMU merging doesn't change the > imposed requirements. If these requirements slow you down you need > to relax them, as apparently the hardware is able to handle bigger > limits. Hans, don't you have the right equipment to test this approach? Alan Stern
