Hi Peter,
> -----Original Message-----
> From: Peter Maydell <peter.mayd...@linaro.org>
> Sent: Wednesday, February 26, 2020 9:59 PM
> To: Sai Pavan Boddu <saip...@xilinx.com>
> Cc: pbonz...@redhat.com; QEMU Developers <qemu-devel@nongnu.org>;
> Edgar Iglesias <edg...@xilinx.com>
> Subject: Re: Implementing IOMMU support for SDHCI
>
> On Wed, 26 Feb 2020 at 12:38, Sai Pavan Boddu <saip...@xilinx.com>
> wrote:
> >
> > Hi Poalo/Peter,
> >
> > We are trying to add SMMU support for dma's used in SD controller on
> ZynqMP boards. In order to do that we need a clean way to assign
> MemTxAttrs to each device(i.e all devices which connect to smmu) via
> "object_add_link_property/ object_set_link_property " functions.
> >
> > But in order to do that, first we may need to convert MemTxAttrs as QOM
> object. I just need some feedback, if its advisable to do so ?
>
> We create and throw around MemTxAttrs structs a lot, I don't think they're
> suitable to be QOM objects. I don't think you need it, anyway -- your problem
> is rather that the iommu doesn't get an opportunity to sit in the middle of
> transactions the way you'd like it to, and making MemTxAttrs a QOM object
> doesn't help address that.
[Sai Pavan Boddu] Our idea is to create dma helper function which can also pass
the MemTxAttr i.e like
dma_memory_rw_attr (AddressSpace *as, dma_addr_t addr,
void *buf, dma_addr_t len,
DMADirection dir,
MemTxAttrs attr)
which needs to be used in sdhci, with "AddressSpace *as" pointing to smmu.
I see we don’t need QOM variant of MemTxAttr for this functionality, but
thought it would be good to use " object_add_link_property/
object_set_link_property " to set the values from machine file's. I would drop
this idea, and look for other options to set the attributes.
Regards,
Sai Pavan
>
> thanks
> -- PMM
