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SubjectRe: [PATCH V3] pci: exynos: split into two parts such as Synopsys part and Exynos part
Hi Kishon,


On Sun, Sep 22, 2013 at 07:16:34PM +0800, Kishon Vijay Abraham I wrote:
> Hi Arnd,
>
> Thanks for replying :-)
>
> On Sunday 22 September 2013 03:33 AM, Arnd Bergmann wrote:
> > On Saturday 21 September 2013, Kishon Vijay Abraham I wrote:
> >> {
> >> u32 val;
> >> void __iomem *val1;
> >> void __iomem *dbi_base = pp->dbi_base;
> >>
> >> /* Program viewport 0 : INBOUND : MEMORY*/
> >> val = PCIE_ATU_REGION_INBOUND | (0 & 0xF);
> >> dw_pcie_writel_rc(pp, val, dbi_base + PCIE_ATU_VIEWPORT);
> >> val1 = ioremap(0x80000000, 0x5fffffff);
> >
> > The ioremap here makes no sense at all, and I suspect it will fail anyway,
> > because you exhaust the vmalloc area size, but since the value is not
> > used anywhere, it won't matter.
> >
> >> dw_pcie_writel_rc(pp, 0x80000000, dbi_base + PCIE_ATU_LOWER_BASE);
> >> dw_pcie_writel_rc(pp, 0, dbi_base + PCIE_ATU_UPPER_BASE);
> >> /* in_mem_size must be in power of 2 */
> >> dw_pcie_writel_rc(pp, 0x5FFFFFFF, dbi_base + PCIE_ATU_LIMIT);

This is wrong. You should program here 0xBFFFFFFF.

Translation rule is as follows:

Region between "Start Address" and "End Address" is translated to
"Target Address" with region size = "End Address" - "Start Address".
Where: Start Address = (PCIE_ATU_UPPER_BASE | PCIE_ATU_LOWER_BASE)
End Address = (PCIE_ATU_UPPER_BASE | PCIE_ATU_LIMIT)
Target Address = (PCIE_ATU_UPPER_TARGET | PCIE_ATU_LOWER_TARGET)

> >> dw_pcie_writel_rc(pp, 0x80000000, dbi_base + PCIE_ATU_LOWER_TARGET);
> >> dw_pcie_writel_rc(pp, 0, dbi_base + PCIE_ATU_UPPER_TARGET);
> >
> > These numbers need to come from somewhere, you shouldn't just hardcode them,
>
> right. I'm still in the process of getting it work ;-)
> >
> > I guess you should either program an inbound window covering the entire 64-bit
> > address space, or you should look at the top-level "memory" nodes to find
> > the location of physical RAM.
> >
> > I can't see anything wrong with the way it's set up though, unless you have
> > an IOMMU. Can you confirm that there is no IOMMU (aka SMMU) in your system
> > that handles the PCIe root complex?
>
> There is a MMU for PCIe root complex but that's disabled.
> >
> >> I somehow starting to doubt the DMA address programmed in the ethernet card
> >> which is in my RAM address range (0x80000000 to 0xBFFFFFFF). Should this
> >> address be programmed in the BAR of the ethernet card? How should it be done?
> >
> > No, it should not be in the BAR. The ethernet device driver calls dma_map_*
> > or pci_map_* interfaces to get a valid token that can be passed into the
> > device registers that are starting the DMA. You have to ensure that the
> > dma_map_ops for the device return the value that is set up in the translation.
> >
> > The normal case is an identity mapping between device DMA space and host
> > memory space, i.e. PCIE_ATU_LOWER_TARGET == PCIE_ATU_LOWER_BASE, so
> > in the dma_map_single implementation, phys_addr_t == dma_addr_t.
> >
> > If you set up the dma_addr_t space to start at 0 instead, you have to add
> > the offset in the dma_map_ops.
>
> My DMA address is in 0x80000000 to 0xBFFFFFFF range and I program my inbound
> translation for this range. Not sure what is missing still :-(

Hope, above modification helps. Let me know.

Regards
Pratyush
>
> Thanks
> Kishon


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