On 06/12/2016 06:12, Vinod Koul wrote:
> On Tue, Nov 29, 2016 at 07:25:02PM +0100, Mason wrote:
>
>> Is there a way to write a driver within the existing framework?
>
> I think so, looking back at comments from Russell, I do tend to agree with
> that. Is there a specific reason why sbox can't be tied to alloc and free
> channels?
Here's a recap of the situation.
The "SBOX+MBUS" HW is used in several iterations of the tango SoC:
tango3
2 memory channels available
6 devices ("clients"?) may request an MBUS channel
tango4 (one more channel)
3 memory channels available
7 devices may request an MBUS channel :
NFC0, NFC1, SATA0, SATA1, memcpy, (IDE0, IDE1)
Notes:
The current NFC driver supports only one controller.
IDE is mostly obsolete at this point.
tango5 (SATA gets own dedicated MBUS channel pair)
3 memory channels available
5 devices may request an MBUS channel :
NFC0, NFC1, memcpy, (IDE0, IDE1)
If I understand the current DMA driver (written by Mans), client
drivers are instructed to use a specific channel in the DT, and
the DMA driver muxes access to that channel. The DMA driver
manages a per-channel queue of outstanding DMA transfer requests,
and a new transfer is started friom within the DMA ISR
(modulo the fact that the interrupt does not signal completion
of the transfer, as explained else-thread).
What you're proposing, Vinod, is to make a channel exclusive
to a driver, as long as the driver has not explicitly released
the channel, via dma_release_channel(), right?
Regards.
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