On 20.10.2017 00:58, Rob Herring wrote:
> On Thu, Oct 19, 2017 at 6:14 AM, Alexandre Belloni
> <[email protected]> wrote:
>> On 13/10/2017 at 16:51:42 -0500, Rob Herring wrote:
>>> On Wed, Oct 11, 2017 at 09:35:28AM +0300, Eugen Hristev wrote:
>>>> Added property for DMA configuration of the device.
>>>>
>>>> Signed-off-by: Eugen Hristev <[email protected]>
>>>> ---
>>>> Documentation/devicetree/bindings/iio/adc/at91-sama5d2_adc.txt | 7 +++++++
>>>> 1 file changed, 7 insertions(+)
>>>>
>>>> diff --git a/Documentation/devicetree/bindings/iio/adc/at91-sama5d2_adc.txt b/Documentation/devicetree/bindings/iio/adc/at91-sama5d2_adc.txt
>>>> index 552e7a8..5f94d479 100644
>>>> --- a/Documentation/devicetree/bindings/iio/adc/at91-sama5d2_adc.txt
>>>> +++ b/Documentation/devicetree/bindings/iio/adc/at91-sama5d2_adc.txt
>>>> @@ -17,6 +17,11 @@ Required properties:
>>>> This property uses the IRQ edge types values: IRQ_TYPE_EDGE_RISING ,
>>>> IRQ_TYPE_EDGE_FALLING or IRQ_TYPE_EDGE_BOTH
>>>>
>>>> +Optional properties:
>>>> + - dmas: Phandle to dma channel for the ADC.
>>>> + See ../../dma/dma.txt for details.
>>>> + - dma-names: Must be "rx" when dmas property is being used.
>>>
>>> -names is pointless when there is only one.
>>>
>>
>> You didn't reply to the question I had previously about that: What if at
>> some point, we have multiple dmas in the same binding?
>
> Then add dma-names at that point and rx has to be first. If you know
> there's other channels, then add them now. Don't evolve the bindings
> needlessly based on what a driver supports.
>
> Would another channel make sense here? Maybe multi-channel rx in which
> case your naming wouldn't be setup for that. But "tx" on an ADC?
>
> Rob
Hello Rob,
I can keep only "dmas" and remove "dma-names", but then, the API used by
the drivers that request channels requires a name parameter
(dma_request_slave_channel), and it will look always inside the
"dma-names" property to match the name and find the proper channel, and
it will fail in this case.
Looking in the general dma binding (dma.txt) I can see that both
properties are marked as required for a client driver, so that's why
I added both.
I can either keep dma-names; or try to find the channel properties by
looking directly into the OF node and create the dma_chan struct inside
my driver (maybe call some xlate function for the DMA controller), but
still need to get the DT property. A complicated option would be to
actually create an API inside the dmaengine to find a channel without
name.
Which approach you think it's best to pursue ?
Thanks,
Eugen
>
From 1583406785873528743@xxx Tue Nov 07 11:33:04 +0000 2017
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On Tue, Nov 07, 2017 at 10:49:41AM +0200, Eugen Hristev wrote:
>
>
> On 20.10.2017 00:58, Rob Herring wrote:
> > On Thu, Oct 19, 2017 at 6:14 AM, Alexandre Belloni
> > <[email protected]> wrote:
> > > On 13/10/2017 at 16:51:42 -0500, Rob Herring wrote:
> > > > On Wed, Oct 11, 2017 at 09:35:28AM +0300, Eugen Hristev wrote:
> > > > > Added property for DMA configuration of the device.
> > > > >
> > > > > Signed-off-by: Eugen Hristev <[email protected]>
> > > > > ---
> > > > > Documentation/devicetree/bindings/iio/adc/at91-sama5d2_adc.txt | 7 +++++++
> > > > > 1 file changed, 7 insertions(+)
> > > > >
> > > > > diff --git a/Documentation/devicetree/bindings/iio/adc/at91-sama5d2_adc.txt b/Documentation/devicetree/bindings/iio/adc/at91-sama5d2_adc.txt
> > > > > index 552e7a8..5f94d479 100644
> > > > > --- a/Documentation/devicetree/bindings/iio/adc/at91-sama5d2_adc.txt
> > > > > +++ b/Documentation/devicetree/bindings/iio/adc/at91-sama5d2_adc.txt
> > > > > @@ -17,6 +17,11 @@ Required properties:
> > > > > This property uses the IRQ edge types values: IRQ_TYPE_EDGE_RISING ,
> > > > > IRQ_TYPE_EDGE_FALLING or IRQ_TYPE_EDGE_BOTH
> > > > >
> > > > > +Optional properties:
> > > > > + - dmas: Phandle to dma channel for the ADC.
> > > > > + See ../../dma/dma.txt for details.
> > > > > + - dma-names: Must be "rx" when dmas property is being used.
> > > >
> > > > -names is pointless when there is only one.
> > > >
> > >
> > > You didn't reply to the question I had previously about that: What if at
> > > some point, we have multiple dmas in the same binding?
> >
> > Then add dma-names at that point and rx has to be first. If you know
> > there's other channels, then add them now. Don't evolve the bindings
> > needlessly based on what a driver supports.
> >
> > Would another channel make sense here? Maybe multi-channel rx in which
> > case your naming wouldn't be setup for that. But "tx" on an ADC?
> >
> > Rob
>
> Hello Rob,
>
> I can keep only "dmas" and remove "dma-names", but then, the API used by
> the drivers that request channels requires a name parameter
> (dma_request_slave_channel), and it will look always inside the
> "dma-names" property to match the name and find the proper channel, and
> it will fail in this case.
>
> Looking in the general dma binding (dma.txt) I can see that both
> properties are marked as required for a client driver, so that's why
> I added both.
>
I don't understand why dma-names should be removed. For sure, if we have
only one channel, it becomes useless but the helpers to get a dma channel
rely on dma-names property.
Ludovic
> I can either keep dma-names; or try to find the channel properties by
> looking directly into the OF node and create the dma_chan struct inside
> my driver (maybe call some xlate function for the DMA controller), but
> still need to get the DT property. A complicated option would be to
> actually create an API inside the dmaengine to find a channel without
> name.
>
> Which approach you think it's best to pursue ?
>
> Thanks,
> Eugen
>
>
>
> >
From 1581728042228576446@xxx Thu Oct 19 22:50:09 +0000 2017
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