On Mon, Jul 30, 2018 at 8:14 PM, Oleksij Rempel <o.rempel@xxxxxxxxxxxxxx> wrote:
> On Mon, Jul 30, 2018 at 06:34:56PM +0530, Jassi Brar wrote:
>> On Mon, Jul 30, 2018 at 1:05 PM, Oleksij Rempel <o.rempel@xxxxxxxxxxxxxx> wrote:
>> > Hi Aishen, Jassie,
>> >
>> > i'm lost in this discussion. Please, as soon as I need to add some
>> > changes to my patches, notify me. Preferably on top for email.
>> >
>> I am ok with however you choose to implement, 8 unidirectional or 4
>> bidirectional channels or whatever.
>>
>> We just can't have protocol specific s/w modes in the controller drivers.
>>
>> The best solution is to fix the SCU firmware. If that is _really_
>> impossible, I provided a solution (3 cells work around). If you have a
>> better idea please feel free to propose and implement that.
>>
>> It will also help if you could share the user code of "scu-mode". If
>> there is no such code (and we know the driver doesn't respect the
>> "scu-mode" property) why do we even have that binding? Maybe drop it.
>
> Tomorrow I have a time slot to address your generic iMX MU suggestions.
> So, what is better, uni- or bi-directional channels?
>
The datasheet indicates there are 4 tx and 4 rx channels. So 8
uni-directional channels (which allow more fine-grained/efficient
resource allocation btw).
> Should I implement
> *all* (4TX+FIFO, 4RX+FIFO, 4TX-simple, 4RX-simple) channels in this run?
>
>From datasheet, each of 8 channels should be defined as signal+data
i.e, IRQ + TX/RX_Reg.
The rest 4 GP channels are doorbells (irq only).
So we can have 2-cells.
First cell is 0->Tx, 1->RX, 2->Doorbell
Second cell is index of the channel {0,3}
Now you may implement only RX+TX, and leave 'doorbell' out for future.
Thats ok, because we wouldn't have to change bindings then.
However, if SCU (in its current form) must be supported. We may need
to add the third cell (irq enable or not) or some better way, right
now.
> If yes, how should it be reflected in DT?
> - 1 cell: &mu [0-15]
> - 2 cells: &mu [0-7] [TX,RX]
> - 3 cells: &mu [0-4] [FIFO,NOFIFO] [TX,RX]
>
It may be possible for a device binding to have variable cells, but I
haven't seen any. And I am not sure that would look neat either.
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