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From: Mark Brown <broonie@kernel.org>
To: Alexander Sverdlin <alexander.sverdlin@nokia.com>
Cc: linux-spi@vger.kernel.org, devicetree@vger.kernel.org,
	Rob Herring <robh+dt@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>
Subject: Re: [PATCH] spi: pl022: Add OF binding to disable DMA usage
Date: Wed, 1 Aug 2018 11:39:49 +0100	[thread overview]
Message-ID: <20180801103949.GE5509@sirena.org.uk> (raw)
In-Reply-To: <150e4a91-e607-ee7c-20bc-9ed81019f1da@nokia.com>

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On Thu, Jul 26, 2018 at 11:04:24AM +0200, Alexander Sverdlin wrote:
> On 25/07/18 19:06, Mark Brown wrote:

> > this or if we shouldn't instead be looking at improving the driver to
> > work better in systems with limited channels, for example by only
> > claiming the channels when it's active (since it can fall back to PIO if
> > it doesn't get them).  That might be too heavyweight though, possibly

> yes, this is an option as well, but at the time we need to take this decision
> the bus scan has not yet been performed. We could scan all the devices in
> the DT and check if any of them requires DMA. This would mean, that
> probe() of the PL022 driver will include similar code to the bus scan
> that anyway will happen later just to take the decision on DMA usage.

> But I'm fine with that. If this sounds better than new boolean DT binding,
> I'll send another patch.

I'm not 100% clear I follow what you mean by bus scan here but I *think*
that sounds about right.  The channel request/release could be factored
out into helper functions to minimize duplication.

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  reply	other threads:[~2018-08-01 10:39 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-07-24 11:27 [PATCH] spi: pl022: Add OF binding to disable DMA usage Alexander Sverdlin
2018-07-25 17:06 ` Mark Brown
2018-07-26  9:04   ` Alexander Sverdlin
2018-08-01 10:39     ` Mark Brown [this message]
2018-08-01 10:47       ` Alexander Sverdlin
2018-08-02 11:45         ` Mark Brown
2018-07-31 21:53 ` Rob Herring

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