Messages in this thread |  | | Date | Sun, 7 Oct 2001 09:21:05 +0200 (CEST) | From | Gérard Roudier <> | Subject | Re: how to get virtual address from dma address |
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On 6 Oct 2001, Jes Sorensen wrote:
> >>>>> "Paul" == Paul Mackerras <paulus@samba.org> writes: > > Paul> David S. Miller writes: > >> I can not even count on one hand how many people I've helped > >> converting, who wanted a bus_to_virt() and when I showed them how > >> to do it with information the device provided already they said "oh > >> wow, I never would have thought of that". That process won't > >> happen as often with the suggested feature. > > Paul> Well, let's see if we can come up with a way to achieve this > Paul> goal as well as the other. > > Paul> I look at all the hash-table stuff in the usb-ohci driver and I > Paul> think to myself about all the complexity that is there (and I > Paul> haven't managed to convince myself yet that it is actually > Paul> SMP-safe) and all the time wasted doing that stuff, when on > Paul> probably 95% of the machines that use the usb-ohci driver, the > Paul> hashing stuff is totally unnecessary. I am talking about > Paul> powermacs, which don't have an iommu, and where the reverse > Paul> mapping is as simple as adding a constant. > > I haven't looked at the ohci driver at all, however doesn't it return > anything but the dma address? No index, no offset, no nothing? If > thats the case, someone really needs to go visit the designers with a > large bat ;-(
I would apply the bat to people that wants such a dma to virtual general translation. This thing is obviously gross shit.
I would also apply the bat to people that look into stuff of other people and, instead of trying to actually understand the code, just give a look and send inappropriate statements to the list.
Gérard.
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