RDMA/core: Set DMA parameters correctly

The dma_set_max_seg_size() call in setup_dma_device() does not have any
effect since device->dev.dma_parms is NULL. Fix this by initializing
device->dev.dma_parms first.

Link: https://lore.kernel.org/r/[e-mail]
Fixes: d10bcf947a3e ("RDMA/umem: Combine contiguous PAGE_SIZE regions in SGEs")
Signed-off-by: Bart Van Assche <[e-mail]>
Reviewed-by: Jason Gunthorpe <[e-mail]>
Signed-off-by: Jason Gunthorpe <[e-mail]>

drivers/infiniband/core/device.c

···
 		WARN_ON_ONCE(!parent);
 		device->dma_device = parent;
 	}
-	/* Setup default max segment size for all IB devices */
-	dma_set_max_seg_size(device->dma_device, SZ_2G);
 
+	if (!device->dev.dma_parms) {
+		if (parent) {
+			/*
+			 * The caller did not provide DMA parameters, so
+			 * 'parent' probably represents a PCI device. The PCI
+			 * core sets the maximum segment size to 64
+			 * KB. Increase this parameter to 2 GB.
+			 */
+			device->dev.dma_parms = parent->dma_parms;
+			dma_set_max_seg_size(device->dma_device, SZ_2G);
+		} else {
+			WARN_ON_ONCE(true);
+		}
+	}
 }
 
 /*