The bus address is not same as physical address on all architectures, however on Intel arch, it is same.
On the other lines, please check the VME specification if it does not require bounce buffers to handle higher physical address.
May be you find something useful here:
Thanks,
Rajat
2010/10/23 Sekhar Pedamallu <kernel.sekhar@xxxxxxxxx>
Hi,
Request you to check if the memory allocation is done using GFP_DMA
in kmalloc ???
Thanks
Sekhar
2010/10/20 Trübenbach, Ralf <Ralf.Truebenbach@xxxxxx>:
> Hello,
>
> I have a problem with our VME driver (sources see below) and high
> memory. I would like to transfer the content of a user space alloced
> buffer to another VME device using DMA (see vme4l-core.c->vme4l_zc_dma()).
> The actual driver version uses page_address() and virt_to_bus() to get
> the bus addresses needed to fill the DMA scatter list. Unfortunately
> this is not working with highmem.
>
> I tried with page_to_phys() instead of page_address/virt_to_bus which
> seems to work. But is this correct for all architectures? As far as I
> understood I have to use the bus addresses and not the physical
> addresses to fill the DMA scatter list.
>
> Maybe someone knows an example where I can have a look at, or any other
> suggestions?
>
> Thank you,
>
> Ralf
>
>
> Sources:
> --------
> http://codeviewer.org/view/code:12ed vme4l-core.c
> http://codeviewer.org/view/code:12ee vme4l-tsi148.c
> http://codeviewer.org/view/code:12ef vme4l-tsi148.h
> http://codeviewer.org/view/code:12f0 vme4l-menpldz002.c
> http://codeviewer.org/view/code:12f1 vme4l-core.h
> or (complete):
> http://www.men.de/download/free/13z014-90/13z014-90_02_11.zip
>
> Best Regards/Mit freundlichen Gruessen
>
> Ralf Trübenbach
>
> ------------------------------------------------------------------------
>
> Ralf Trübenbach, Software Design
> MEN Mikro Elektronik GmbH
> Neuwieder Straße 5-7
> 90411 Nürnberg, Germany
> Phone +49-911-99 33 5-0
> Fax +49-911-99 33 5-910
> Ralf.Truebenbach@xxxxxx
> www.men.de
>
>
>
> MEN Mikro Elektronik GmbH - Manfred Schmitz (CTO), Udo Fuchs (CFO)
> - Handelsregister/Trade Register AG Nürnberg HRB 5540
>
>
>
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