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SubjectRe: b44 driver causes panic when using swiotlb
On Tue, Feb 1, 2011 at 12:07 PM, Andi Kleen <> wrote:
> On Mon, Jan 31, 2011 at 06:54:21PM -0600, Robert Hancock wrote:
>> On 01/31/2011 10:36 AM, Andi Kleen wrote:
>> >On Mon, Jan 31, 2011 at 10:54:12AM -0500, Chuck Ebbert 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:
>> >
>> >b44 needs to use GFP_DMA then and do its own custom bouncing.
>> >The standard pci_map_* bounce buffering is only designed for at least
>> >32bit capable devices.
>> That seems wrong - it's a documented API and that restriction isn'
> Please read the documentation. When PCI DMA cannot handle it
> it returns failure. That is what happened here.

Apparently not, given that it hit a panic inside the swiotlb code..
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