Messages in this thread | | | From | (H. Peter Anvin) | Subject | Re: [PATCH] aic7xxx large integer | Date | Mon, 6 Dec 2004 21:35:05 +0000 (UTC) |
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Followup to: <1102208526.6052.87.camel@localhost> By author: Robert Love <rml@novell.com> In newsgroup: linux.dev.kernel > > On Sun, 2004-12-05 at 00:16 +0100, Miguel Angel Flores wrote: > > > I post the patch very quickly :(. The original code finally seems OK. My > > controller is not working with 39 bit addressing, although I can't find > > why the compiler warns. Maybe the length of dma_addr_t type, in the > > 2.6.9 the type of the mask_39bit variable is bus_addr_t. > > The compiler warns because you are putting a 64-bit value (an unsigned > long long) in a 32-bit value (a u32). > > There is definitely a problem on non-highmem compiled kernels, there is > no doubt of that. The concern was that your suggested fix is not right. > > Assuming that a 39-bit value is really wanted, the type either needs to > be changed to a dma64_addr_t or the value needs to change at > compile-time to a suitable 32-bit variant when !CONFIG_HIGHMEM64G. > > Without knowing what the driver is doing, I have no idea. >
I suspect that what the driver wants is a mask that is a valid DMA address no wider than 39 bits (because that's all the hardware can do.)
If so, I would assume (dma_addr_t)0x7FFFFFFFFFULL is probably the right thing; it will be truncated to a 32-bit mask if only 32-bit addressing is available.
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