From: jeff.boyd@att•net
To: linuxppc-embedded@lists•linuxppc.org
Subject: 36 bit DMA address on IBM 440 PPC
Date: Mon, 10 Mar 2003 13:15:57 +0000 [thread overview]
Message-ID: <200303101316.HAA25661@lists.linuxppc.org> (raw)
I am having a problem doing PCI/memory DMA on the IBM 440 PPC because it has a
36 bit DMA address to/from the PCI bus (3_8000_0000), but the resource
structure uses an unsigned long (which is a 32 bit quantity for gcc) to
store 'physical/bus/dma' address. There is a kludge to get proper page table
entries, which is to remap the 32 bit quatities into their 36 bit counterparts
and then sending them on to __ioremap which takes a (36 bit) physical address
input. This of course is no help to DMA, which wants not cpu (virtual) address,
but physical (translated) address. I have done a similar kludge, making the 32
to 36 bit translation into a function which a driver doing DMA can use.
However, it seems to me that the real answer here is to change the resource
definition to use a phys_addr_t rather than an unsigned long, for start/end.
Does anyone know if this change has been made anywhere, or if it is being
planned?
** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/
next reply other threads:[~2003-03-10 13:15 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-03-10 13:15 jeff.boyd [this message]
2003-03-10 14:12 ` 36 bit DMA address on IBM 440 PPC Matt Porter
2003-03-11 0:58 ` Jeff Boyd
2003-03-11 4:11 ` Matt Porter
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