USB DMA memory Allocation

[Hans Petter Selasky]

Hi,

I think there are a few bits to put the high 32-bits into the transfer descriptors and such missing. You are right we don`t really need to use 32-bit only for the USB controllers. Though we`ve seen a couple of times that even 32-bit controllers don`t implement the full 32-address lines. Typically 2GB limits are found.

--HPS 
 
-----Original message-----
> From:aseem.jolly <aseem.jolly at gmail.com <mailto:aseem.jolly at gmail.com> >
> Sent: Saturday 3rd August 2013 2:17
> To: freebsd-usb at freebsd.org <mailto:freebsd-usb at freebsd.org> 
> Subject: USB DMA memory Allocation
> 
> It seems to me that Intel ehci controller supports 64 DMA address lines
> (HCCPARAMS register's 0 bit is set hardwired) then why do force DMA
> allocation from [0 4GB] range.
> 
> I tried to enable 64 bit DMA allocations by modifying call to
> 'usb_dma_tag_setup' in usb_controller.c and usb_transfer.c but got a device
> disconnect after we preallocated DMA memory for USB transfers.
> 
> Would be really great if someone could guide me on this.
> 
> 
> 
> 
> --
> View this message in context: http://freebsd.1045724.n5.nabble.com/USB-DMA-memory-Allocation-tp5833506.html <http://freebsd.1045724.n5.nabble.com/USB-DMA-memory-Allocation-tp5833506.html> 
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