linux-kernel - Re: [PATCH v4 06/11] iio: backend: extend features

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Message-ID: <ihkd45xlg3hejchdw6ksmuzoxu3cazmx5rd4d4zca7xl4rfcrd@krururfftdlx>
Date: Fri, 4 Oct 2024 15:45:21 +0200
From: Angelo Dureghello <adureghello@...libre.com>
To: Nuno Sá <noname.nuno@...il.com>
Cc: Lars-Peter Clausen <lars@...afoo.de>, 
	Michael Hennerich <Michael.Hennerich@...log.com>, Nuno Sa <nuno.sa@...log.com>, 
	Jonathan Cameron <jic23@...nel.org>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Mihail Chindris <mihail.chindris@...log.com>, Olivier Moysan <olivier.moysan@...s.st.com>, 
	linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Jonathan Cameron <Jonathan.Cameron@...wei.com>, devicetree@...r.kernel.org, dlechner@...libre.com, 
	Mark Brown <broonie@...nel.org>
Subject: Re: [PATCH v4 06/11] iio: backend: extend features

Hi Nuno,

On 04.10.2024 14:54, Nuno Sá wrote:
> On Thu, 2024-10-03 at 19:29 +0200, Angelo Dureghello wrote:
> > From: Angelo Dureghello <adureghello@...libre.com>
> > 
> > Extend backend features with new calls needed later on this
> > patchset from axi version of ad3552r.
> > 
> > The follwoing calls are added:
> > 
> > iio_backend_ddr_enable
> > 	enable ddr bus transfer
> > iio_backend_ddr_disable
> > 	disable ddr bus transfer
> > iio_backend_buffer_enable
> > 	enable buffer
> > iio_backend_buffer_disable
> > 	disable buffer
> > iio_backend_data_transfer_addr
> > 	define the target register address where the DAC sample
> > 	will be written.
> > 
> > Signed-off-by: Angelo Dureghello <adureghello@...libre.com>
> > ---
> >  drivers/iio/industrialio-backend.c | 79 ++++++++++++++++++++++++++++++++++++++
> >  include/linux/iio/backend.h        | 17 ++++++++
> >  2 files changed, 96 insertions(+)
> > 
> > diff --git a/drivers/iio/industrialio-backend.c b/drivers/iio/industrialio-
> > backend.c
> > index 20b3b5212da7..d5e0a4da761e 100644
> > --- a/drivers/iio/industrialio-backend.c
> > +++ b/drivers/iio/industrialio-backend.c
> > @@ -718,6 +718,85 @@ static int __devm_iio_backend_get(struct device *dev, struct
> > iio_backend *back)
> >  	return 0;
> >  }
> >  
> > +/**
> > + * iio_backend_ddr_enable - Enable interface DDR (Double Data Rate) mode
> > + * @back: Backend device
> > + *
> > + * Enable DDR, data is generated by the IP at each front (raising and falling)
> > + * of the bus clock signal.
> > + *
> > + * RETURNS:
> > + * 0 on success, negative error number on failure.
> > + */
> > +int iio_backend_ddr_enable(struct iio_backend *back)
> > +{
> > +	return iio_backend_op_call(back, ddr_enable);
> > +}
> > +EXPORT_SYMBOL_NS_GPL(iio_backend_ddr_enable, IIO_BACKEND);
> > +
> > +/**
> > + * iio_backend_ddr_disable - Disable interface DDR (Double Data Rate) mode
> > + * @back: Backend device
> > + *
> > + * Disable DDR, setting into SDR mode (Single Data Rate).
> > + *
> > + * RETURNS:
> > + * 0 on success, negative error number on failure.
> > + */
> > +int iio_backend_ddr_disable(struct iio_backend *back)
> > +{
> > +	return iio_backend_op_call(back, ddr_disable);
> > +}
> > +EXPORT_SYMBOL_NS_GPL(iio_backend_ddr_disable, IIO_BACKEND);
> > +
> > +/**
> > + * iio_backend_dma_stream_enable - Enable iio buffering
> > + * @back: Backend device
> > + *
> > + * Enabling sending the dma data stream over the bus.
> > + * bus interface.
> > + *
> > + * RETURNS:
> > + * 0 on success, negative error number on failure.
> > + */
> > +int iio_backend_dma_stream_enable(struct iio_backend *back)
> > +{
> > +	return iio_backend_op_call(back, dma_stream_enable);
> > +}
> > +EXPORT_SYMBOL_NS_GPL(iio_backend_dma_stream_enable, IIO_BACKEND);
> > +
> > +/**
> > + * iio_backend_dma_stream_disable - Disable iio buffering
> > + * @back: Backend device
> > + *
> > + * Disable sending the dma data stream over the bus.
> > + *
> > + * RETURNS:
> > + * 0 on success, negative error number on failure.
> > + */
> > +int iio_backend_dma_stream_disable(struct iio_backend *back)
> > +{
> > +	return iio_backend_op_call(back, dma_stream_disable);
> > +}
> > +EXPORT_SYMBOL_NS_GPL(iio_backend_dma_stream_disable, IIO_BACKEND);
> > +
> 
> I'm not sure if this is what Jonathan was suggesting... Ate least I don't really
> agree with it. I mean, yes, this is about buffering and to start receiving (or
> sending) a stream of data. But AFAICT, it might have nothing to do with DMA. Same as
> .request_buffer() - It's pretty much always a DMA one but we should not take that for
> granted.
> 
> So going back to the RFC [1], you can see I was suggesting something like struct
> iio_buffer_setup_ops. Maybe just add the ones we use for now? So that would
> be.buffer_postenable() and .buffer_predisable(). Like this, it should be obvious the
> intent of the ops.
> 
ok, thanks,

so something as :

struct iio_backend_setup_ops {
	int (*buffer_postenable)(struct iio_backend *back);
	int (*buffer_predisable)(struct iio_backend *back);
};

struct iio_backend_ops {
	struct iio_backend_setup_ops setup_ops;

?

> - Nuno Sá
> 
> 

-- 

Regards,
  Angelo