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From: Mark Brown <broonie@kernel.org>
To: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: linux-spi <linux-spi@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2] spi/drivers: Restrict COMPILE_TEST by HAS_DMA where needed
Date: Sun, 31 Aug 2014 14:05:16 +0100	[thread overview]
Message-ID: <20140831130516.GH29327@sirena.org.uk> (raw)
In-Reply-To: <CAMuHMdXqFSv9B-OuGYGBfb5NReLQNRJat5_9=uBdSct7_3sQOg@mail.gmail.com>

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On Sun, Aug 31, 2014 at 10:39:09AM +0200, Geert Uytterhoeven wrote:
> On Fri, Aug 29, 2014 at 9:13 PM, Geert Uytterhoeven

> >> I'm wondering if it isn't better to have the non-DMA platforms define
> >> stub (always error) DMA functions instead - it's less error prone and
> >> with SPI there's a bunch of drivers which can run perfectly usefully
> >> without DMA while optionally supporting DMA.

> > The SPI problem will sort itself out once all SPI master drivers have been
> > converted to use the SPI DMA core ;-)

> BTW, the dmaengine API has stubs, only the low-level dma-mapping API
> doesn't. That's why e.g. spi-rspi doesn't need a dependency on HAS_DMA.
> So it's indeed a good thing to handle the low-level DMA mapping in the
> subsystem's core, as only that part can be optional and depend on HAS_DMA.

Yeah, but I'd expect there's other subsystems which will be in a similar
boat here and with dmaengine having stubs it seems strange that the
mapping API doesn't.

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  reply	other threads:[~2014-08-31 13:05 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-08-29 16:10 Geert Uytterhoeven
2014-08-29 17:37 ` Mark Brown
2014-08-29 19:13   ` Geert Uytterhoeven
2014-08-31  8:39     ` Geert Uytterhoeven
2014-08-31 13:05       ` Mark Brown [this message]
2014-08-31 13:00 ` Mark Brown

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