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From: Rob Herring <robh@kernel.org>
To: Alexander Sverdlin <alexander.sverdlin@nokia.com>
Cc: linux-spi@vger.kernel.org, devicetree@vger.kernel.org,
	Mark Brown <broonie@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>
Subject: Re: [PATCH] spi: pl022: Add OF binding to disable DMA usage
Date: Tue, 31 Jul 2018 15:53:10 -0600	[thread overview]
Message-ID: <20180731215310.GA24997@rob-hp-laptop> (raw)
In-Reply-To: <20180724112753.6020-1-alexander.sverdlin@nokia.com>

On Tue, Jul 24, 2018 at 01:27:53PM +0200, Alexander Sverdlin wrote:
> Legacy platform instantiation of PL022 had an ability to configure DMA
> usage on controller level. If PL022 is being instantiated from DT it still
> claims couple of DMA channels capable of DMA_SLAVE unconditionally even if
> there are no DMA channels specified in the DT.

How does that work without specifying the channels in DT? Perhaps the 
driver should stop doing that. We can whitelist any platforms that need 
current behavior if someone complains.

> 
> Depending on the slave devices' configuration this might be waste of DMA
> channels or this might even claim some precious DMA channels if there are
> only few of them in the system.
> 
> Add a new boolean property to disable DMA usage on the controller level:
> 	"pl022,dma-disable"
> 
> Signed-off-by: Alexander Sverdlin <alexander.sverdlin@nokia.com>
> ---
>  Documentation/devicetree/bindings/spi/spi_pl022.txt | 1 +
>  drivers/spi/spi-pl022.c                             | 2 +-
>  2 files changed, 2 insertions(+), 1 deletion(-)

      parent reply	other threads:[~2018-07-31 21:53 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
2018-08-01 10:47       ` Alexander Sverdlin
2018-08-02 11:45         ` Mark Brown
2018-07-31 21:53 ` Rob Herring [this message]

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