Re: b44 driver causes panic when using swiotlb

[FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>]

On Mon, 31 Jan 2011 10:54:12 -0500
Chuck Ebbert <cebbert@redhat.com> wrote:

> The b44 driver is triggering this panic in swiotlb_map_page():
> 
>         if (!dma_capable(dev, dev_addr, size))
>                 panic("map_single: bounce buffer is not DMA'ble");
> 
> The kernel log says the bounce buffers are at 0xdb400000, but b44 can
> only do DMA to the first 1GB of memory:

Can you try this? b44 has the own bouncing mechanism so if swiotlb
returns an error, the driver can allocate an appropriate buffer.

diff --git a/lib/swiotlb.c b/lib/swiotlb.c
index c47bbe1..93ca08b 100644
--- a/lib/swiotlb.c
+++ b/lib/swiotlb.c
@@ -686,8 +686,10 @@ dma_addr_t swiotlb_map_page(struct device *dev, struct page *page,
 	/*
 	 * Ensure that the address returned is DMA'ble
 	 */
-	if (!dma_capable(dev, dev_addr, size))
-		panic("map_single: bounce buffer is not DMA'ble");
+	if (!dma_capable(dev, dev_addr, size)) {
+		swiotlb_tbl_unmap_single(dev, map, size, dir);
+		dev_addr = swiotlb_virt_to_bus(dev, io_tlb_overflow_buffer);
+	}
 
 	return dev_addr;
 }