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Date: Sun, 9 Jun 2024 10:11:28 +0100
From: Jonathan Cameron <jic23@kernel.org>
To: Marcelo Schmitt <marcelo.schmitt1@gmail.com>
Cc: Nuno =?UTF-8?B?U8Oh?= <noname.nuno@gmail.com>, David Lechner
 <dlechner@baylibre.com>, Marcelo Schmitt <marcelo.schmitt@analog.com>,
 broonie@kernel.org, lars@metafoo.de, Michael.Hennerich@analog.com,
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 nuno.sa@analog.com, linux-iio@vger.kernel.org, devicetree@vger.kernel.org,
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Subject: Re: [PATCH v3 4/6] spi: spi-axi-spi-engine: Add support for MOSI
 idle configuration
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On Fri, 7 Jun 2024 11:40:23 -0300
Marcelo Schmitt <marcelo.schmitt1@gmail.com> wrote:

> On 06/07, Nuno S=C3=A1 wrote:
> > On Thu, 2024-06-06 at 18:31 -0300, Marcelo Schmitt wrote:
> >=20
> > ...
> >  =20
> > >=20
> > >=20
> > >=20
> > > When is a driver version check needed?
> > > Yes, older versions of SPI-Engine won't support this, but the patch s=
et should
> > > cause no regression. Even if loading the current ad4000 driver with
> > > older SPI-Engine HDL and driver, the ADC driver would get a warn (or =
error?)
> > > and do what's possible without MOSI idle feature (probably only be ab=
le to do
> > > reg access) or fail probing.
> > >  =20
> >=20
> > Maybe I'm missing something but with the patchset we unconditionally set
> > SPI_MOSI_IDLE_HIGH. So if we load an hdl which does not support it thin=
gs will
> > apparently be ok but it won't actually work, right? If I'm right we sho=
uld have =20
> Yes, that's correct.
>=20
> > a bit in a RO config_register telling us that the feature is being supp=
orted or
> > not. That way we only set the mode bit if we do support it... =20
>=20
> Ok, understood. Will do it for v4.
If you don't have such a mode bit, you will need to add a property to the
dt-binding. Or a suitable compatible.

Nasty, so fingers crossed you do have a capability flag to check!

Jonathan

>=20
> Thanks,
> Marcelo
>=20
> >=20
> > - Nuno S=C3=A1
> >=20
> >  =20