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Re: [PATCH 1/2] spi: sun4i: add DMA support

From Mark Brown <broonie@kernel.org>
Newsgroups linux.kernel
Subject Re: [PATCH 1/2] spi: sun4i: add DMA support
Date 2016-03-17 12:50 +0100
Message-ID <rdEBc-6TE-11@gated-at.bofh.it> (permalink)
References (3 earlier) <r6q9Y-3nl-3@gated-at.bofh.it> <r9OIO-2d6-9@gated-at.bofh.it> <rb4Lv-4EC-3@gated-at.bofh.it> <rdAxz-4fU-1@gated-at.bofh.it> <rdDOO-6iN-3@gated-at.bofh.it>
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On Thu, Mar 17, 2016 at 11:58:05AM +0100, Michal Suchanek wrote:
> On 17 March 2016 at 08:27, Maxime Ripard

> > You're mixing two things up: the fact that we can't do more than the
> > FIFO length in PIO and that we're missing DMA support. We have patches
> > to address both, and there's no depedency between the two.

> The only thing is that although DMA is optional on pretty much any
> system you will have DMA available unless you broke your config. You
> really do want the DMA support when it is available. So there will be
> nobody testing the non-DMA part and it will be prone to bitrot.

Well, it might be worth doing PIO for very short transfers even if you
have DMA - it's quite common for this to perform better.

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Thread

Re: [PATCH 1/2] spi: sun4i: add DMA support Maxime Ripard <maxime.ripard@free-electrons.com> - 2016-03-06 22:50 +0100
  Re: [PATCH 1/2] spi: sun4i: add DMA support Michal Suchanek <hramrach@gmail.com> - 2016-03-10 10:10 +0100
    Re: [PATCH 1/2] spi: sun4i: add DMA support Maxime Ripard <maxime.ripard@free-electrons.com> - 2016-03-17 08:30 +0100
      Re: [PATCH 1/2] spi: sun4i: add DMA support Michal Suchanek <hramrach@gmail.com> - 2016-03-17 12:00 +0100
        Re: [PATCH 1/2] spi: sun4i: add DMA support Mark Brown <broonie@kernel.org> - 2016-03-17 12:50 +0100
          Re: [PATCH 1/2] spi: sun4i: add DMA support Michal Suchanek <hramrach@gmail.com> - 2016-03-17 13:00 +0100
            Re: [PATCH 1/2] spi: sun4i: add DMA support Mark Brown <broonie@kernel.org> - 2016-03-17 13:00 +0100
            Re: [PATCH 1/2] spi: sun4i: add DMA support Maxime Ripard <maxime.ripard@free-electrons.com> - 2016-03-18 21:30 +0100
              Re: [PATCH 1/2] spi: sun4i: add DMA support Mark Brown <broonie@kernel.org> - 2016-03-18 21:40 +0100

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