On Wed, May 1, 2013 at 6:30 AM, Dave Airlie airlied@gmail.com wrote:
Since we ask the dmabuf owner to map the dma-buf into our device address space, but for udl at present that is the CPU address space, since we don't DMA directly from the mapped buffer.
However if we don't set a dma mask on the usb device, the mapping ends up using swiotlb on machines that have it enabled, which is less than desireable.
Signed-off-by: Dave Airlie airlied@redhat.com
Fyi for everyone else who was not on irc when Dave&I discussed this: This really shouldn't be required and I think the real issue is that udl creates a dma_buf attachement (which is needed for device dma only), but only really wants to do cpu access through vmap/kmap. So not attached the device should be good enough. Cc'ing a few more lists for better fyi ;-) -Daniel
drivers/gpu/drm/udl/udl_main.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/drivers/gpu/drm/udl/udl_main.c b/drivers/gpu/drm/udl/udl_main.c index 0ce2d71..6770e1b 100644 --- a/drivers/gpu/drm/udl/udl_main.c +++ b/drivers/gpu/drm/udl/udl_main.c @@ -293,6 +293,7 @@ int udl_driver_load(struct drm_device *dev, unsigned long flags) udl->ddev = dev; dev->dev_private = udl;
dma_set_mask(dev->dev, DMA_BIT_MASK(64)); if (!udl_parse_vendor_descriptor(dev, dev->usbdev)) { DRM_ERROR("firmware not recognized. Assume incompatible device\n"); goto err;-- 1.8.2
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-- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch