Re: [PATCHv2 1/3] dt-bindings: spi: Add DT bindings for Synquacer

From: Mark Brown <broonie-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
To: Trent Piepho <tpiepho-cgc2CodaaHDQT0dZR+AlfA@public.gmane.org>
Cc: "jassisinghbrar-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org"
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Subject: Re: [PATCHv2 1/3] dt-bindings: spi: Add DT bindings for Synquacer
Date: Wed, 17 Jan 2018 11:18:18 +0000	[thread overview]
Message-ID: <20180117111817.GA9775@sirena.org.uk> (raw)
In-Reply-To: <1516132926.25398.98.camel-cgc2CodaaHDQT0dZR+AlfA@public.gmane.org>

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On Tue, Jan 16, 2018 at 08:02:06PM +0000, Trent Piepho wrote:
> On Tue, 2018-01-16 at 08:59 +0530, Jassi Brar wrote:

> > Now the idea dawns that DT provide both clocks and the driver select
> > from the mux looking at speed requirements of the slave at runtime.

> add this feature at some point.  It might be simpler to just prefer
> HCLK if both are there.  The idea being that the DT should describe the
> hardware rather than tell the driver what to do.

Or only try one if the other fails to give something.

> Speed can be changed on a xfer by xfer basis on a single message to a
> single slave.  Trying to switch clocks during a message, if it requires
> resetting the whole block, sounds rather difficult.

In practice that's so vanishingly rare it's probably not worth worrying
about.

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