[PATCH RFC] PCI: imx6: remove outbound io/mem ATU region mapping

[Richard Zhu]

Hi Pratyush:

> -----Original Message-----
> From: Pratyush Anand [mailto:pratyush.anand at st.com]
> Sent: Wednesday, November 27, 2013 11:51 AM
> To: Marek Vasut
> Cc: Tim Harvey; Kishon Vijay Abraham I; linux-pci at vger.kernel.org; linux-arm-
> kernel at lists.infradead.org; Bjorn Helgaas; Frank Li; Jingoo Han; Mohit KUMAR
> DCG; Zhu Richard-R65037; Sascha Hauer; Sean Cross; Shawn Guo; Siva Reddy
> Kallam; Srikanth T Shivanand; Troy Kisky; Yinghai Lu
> Subject: Re: [PATCH RFC] PCI: imx6: remove outbound io/mem ATU region mapping
> 
> On Wed, Nov 27, 2013 at 04:46:09AM +0800, Marek Vasut wrote:
> > Dear Pratyush Anand,
> >
> > > Hi,
> > >
> > > On Wed, Oct 23, 2013 at 12:55:43PM +0800, Tim Harvey wrote:
> > > > The IMX6 iATU is used for address translation between the AXI bus
> > > > address space and PCI address space.  This is used for type0 and
> > > > type1 config cycles but is not necessary for outbound io/mem regions.
> > > >
> > > > This patch removes the calls that inappropriately re-configures
> > > > the ATU viewport for outbound memory and IO after config cycles
> > > > and removes them altogether as they are not necessary.
> > > >
> > > > This resolves issues with PCI devices behind switches and has been
> > > > tested with a Gige device behind a PLX PEX860x switch.  More
> > > > testing is needed for other configurations.
> > >
> > > It seems to me that in your controller you have only one view port.
> > > Also mem_base and mem_bus_addr is same. Thats why it works in your
> > > case.
> >
> > MX6 has 4 In/4 Out viewports AFAICT.
> 
> Then if I do not miss anything, MX6 should work even without this patch.

[Richard] Regarding to the commit message, and tests at my side, 
the switch wouldn't work well on imx6 platforms, if "the calls that inappropriately re-configures
 the ATU viewport for outbound memory and IO after config cycles " are not removed.

> 
> Regards
> Pratyush
> >
> > Best regards,
> > Marek Vasut

Best Regards
Richard Zhu