On 07/26/2011 11:32 AM, Rafał Miłecki wrote:
W dniu 26 lipca 2011 17:33 użytkownik Larry Finger
<[email protected]> napisał:
On 07/26/2011 03:24 AM, Rafał Miłecki wrote:
W dniu 25 lipca 2011 23:54 użytkownik Rafał Miłecki<[email protected]>
napisał:
Now, the question: when for real we should use such a solution?
Larry, could you check your driver? Can you see anything about this?
Is this maybe PCI (not PCIe!) specific?
I've checked thread "Interesting 14e4:4321". It seems both: 14e4:4321
and 14e4:4322 are using PCI slot and both are not working in DMA mode.
I start believing it's PCI specific.
If you take a look at current ssb code and defines:
if (ssb_read32(dev, SSB_TMSHIGH)& SSB_TMSHIGH_DMA64)
return SSB_PCIE_DMA_H32;
else
return SSB_PCI_DMA;
You can see 0x80000000 (SSB_PCIE_DMA_H32) has actually "PCIE" in it's
name. This can be true that 0x80000000 is *only* for *64-bit DMA* on
*PCIe*.
That is almost correct. This time I found it. The pseudo code is:
dma_addr_lo = 0
dma_addr_hi = 0
if PCI || PCIe
if PCIe&& 64-bit DMA
dma_addr_hi = 0x80000000
else
if chipID is 0x4322, 43221, 43231, or 43222
dma_addr_lo = 0x80000000
else
dma_addr_lo = 0x40000000<== your case
Thus it is just a little more complicated than a PCI/PCIe split, as it also
depends on the chip ID.
I'll add this to the specs.
Can you (anyone, not just Larry ;) ) give me some tip, how to
implement this correctly? From programming POV.
We should return two infos from ssb code now:
1) Routing bit
2) Address which should be used
Should I add new function for this? Or create struct
dma_translation_info with 2 fields? Or return array? Or...?
How about more pseudo code? Broadcom sets those dma_addr_hi/lo words in a struct
when they are setting up the TX/RX rings. Then they do the following when
actually setting up the 64-bit DMA operation:
dmaaddr_t phys
if !dma_addr_lo || !(phys.loaddr & 0xc0000000)
ring.address_lo = phys.loaddr + dma_addr_lo
ring.address_hi = phys.hiaddr + dma_addr_hi
ring.ctrl1 = ...
else
u32 addr_ext = phys.loaddr & 0xc0000000
phys.loaddr &= ~0xc0000000
ring.address_lo = phys.loaddr + dma_addr_lo
ring.address_hi = dma_addr_hi
ring.ctrl1 = ....
On second thought, what I call dma_addr_{lo,hi} might be called
dma_offset_{lo,hi}, or even dma_mask_{lo,hi}.
As to the programming question, setting up these offsets can easily be done the
way they do.
Larry
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