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Date:      Sat, 03 Nov 2018 15:04:39 -0600
From:      Ian Lepore <ian@freebsd.org>
To:        ticso@cicely.de
Cc:        freebsd-arm@freebsd.org, Bernd Walter <ticso@cicely7.cicely.de>
Subject:   Re: How to add custom dts entries
Message-ID:  <1541279079.52306.8.camel@freebsd.org>
In-Reply-To: <20181103205455.GD79858@cicely7.cicely.de>
References:  <20181103200709.GB79858@cicely7.cicely.de> <1541277990.52306.4.camel@freebsd.org> <20181103205455.GD79858@cicely7.cicely.de>

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On Sat, 2018-11-03 at 21:54 +0100, Bernd Walter wrote:
> On Sat, Nov 03, 2018 at 02:46:30PM -0600, Ian Lepore wrote:
> > 
> > We do have overlay support now. I don't know much about using it,
> > hopefully those who do will reply with details.
> That's good to know.
> Hope for an answer too ;-)
> 
> > 
> > There have also been updates to the SPI world. Your apa102led0 fdt
> > node
> > now requires a "spi-max-frequency" property, the value is the bus
> > speed
> > to use when communicating with that device, in Hz (different
> > devices on
> > the same bus can now have different speeds, and there is no concept
> > of
> > a default speed). Also, the chipsel number should be in a reg=
> > property, but we still support spi-chipselect= too for backwards
> > compatibility. 
> Ah, important information.
> I had been using dev.spi.0.clock to increase speed.
> Obviously dev.spi doesn't even exists anymore.
> Have to check about the CS, technically it is a dummy value anyway,
> since the APA102 LEDs don't have a chip select and are the only
> device connected to the SPI.
> 

The sysctl nodes should still exist, but now they're all read-only
values that just tell you about the current transfer (or the last one
to complete), since all those values can change on each transfer now
depending on how individual devices are configured.

Also, there is now a spi(8) program that lets you do spi transfers and
to some degree manipulate the transfer properties (bus polarity/phase,
speed, etc) from the command line.

-- Ian



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