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SubjectRe: [PATCH 1/3] ata: sata_dwc_460ex: use "dmas" DT property to find dma channel
Andy Shevchenko <> writes:

> On Sun, Dec 20, 2015 at 8:49 PM, Måns Rullgård <> wrote:
>> Julian Margetson <> writes:
>>> On 12/20/2015 1:11 PM, Måns Rullgård wrote:
>>>> Julian Margetson <> writes:
>>> [ 48.769671] ata3.00: failed command: READ FPDMA QUEUED
>> Well, that didn't help. I still think it's part of the problem, but
>> something else must be wrong as well. The various Master Select fields
>> look like a good place to start.
> Master number (which is here would be either 1 or 0) should not affect
> as long as they are connected to the same AHB bus (I would be
> surprised if they are not).

I think they are not. The relevant part of the block diagram for the
460EX looks something like this:

| CPU |
| BUS |
| |
+-----+ +-----+
| DMA | | RAM |
+-----+ +-----+
| SATA |

The DMA-SATA link is private and ignores the address, which is the only
reason the driver can possibly work (it's programming a CPU virtual
address there).

>> Also, the manual says the LLP_SRC_EN
>> and LLP_DST_EN flags should be cleared on the last in a chain of blocks.
>> The old sata_dwc driver does this whereas dw_dma does not.
> Easy to fix, however I can't get how it might affect.

From the Atmel doc:

In Table 17-1 on page 185, all other combinations of LLPx.LOC = 0,
illegal, and causes indeterminate or erroneous behavior.

Most likely nothing happens, but I think it ought to be fixed. In fact,
I have a patch already.

Come to think of it, I have an AVR32 dev somewhere. Maybe I should dust
it off.

Måns Rullgård

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