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Re: [PATCH] dma: sun4i: expose block size and wait cycle configuration to DMA users

From Boris Brezillon <boris.brezillon@free-electrons.com>
Newsgroups linux.kernel
Subject Re: [PATCH] dma: sun4i: expose block size and wait cycle configuration to DMA users
Date 2016-03-11 10:50 +0100
Message-ID <rbrRM-489-7@gated-at.bofh.it> (permalink)
References (2 earlier) <ra4Xf-4ss-5@gated-at.bofh.it> <raa6C-7JQ-5@gated-at.bofh.it> <rag2m-38j-21@gated-at.bofh.it> <raKtu-7bN-45@gated-at.bofh.it> <rboKd-1W9-5@gated-at.bofh.it>
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On Fri, 11 Mar 2016 11:56:07 +0530
Vinod Koul <vinod.koul@intel.com> wrote:

> On Wed, Mar 09, 2016 at 12:06:27PM +0100, Boris Brezillon wrote:
> > On Tue, 8 Mar 2016 08:25:47 +0530
> > Vinod Koul <vinod.koul@intel.com> wrote:
> > > 
> > > Why does dmaengine need to wait? Can you explain that
> > 
> > I don't have an answer for that one, but when I set WAIT_CYCLES to 1
> > for the NAND use case it does not work. So I guess it is somehow
> > related to how the DRQ line is controlled on the device side...
> 
> Is the WAIT cycle different for different usages or same for all
> usages/channels?
> 

In Allwinner BSP they adapt it on a per slave device basis, but since
DMA channels are dynamically allocated, you can't know in advance which
physical channel will be attached to a specific device.

Another option I considered was adding a new cell to the sun4i DT
binding to encode these WAIT_CYCLES and BLOCK_SIZE information. But I'm
not sure adding that to the DT is a good idea (not to mention that it
would break DT ABI again, and given the last discussions on this topic,
I'm not sure it's a good idea :-/).


-- 
Boris Brezillon, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

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Thread

[PATCH] dma: sun4i: expose block size and wait cycle configuration to DMA users Boris Brezillon <boris.brezillon@free-electrons.com> - 2016-03-07 11:30 +0100
  Re: [PATCH] dma: sun4i: expose block size and wait cycle  configuration to DMA users Vinod Koul <vinod.koul@intel.com> - 2016-03-07 16:00 +0100
    Re: [PATCH] dma: sun4i: expose block size and wait cycle  configuration to DMA users Boris Brezillon <boris.brezillon@free-electrons.com> - 2016-03-07 16:10 +0100
      Re: [PATCH] dma: sun4i: expose block size and wait cycle  configuration to DMA users Maxime Ripard <maxime.ripard@free-electrons.com> - 2016-03-07 21:40 +0100
        Re: [PATCH] dma: sun4i: expose block size and wait cycle  configuration to DMA users Vinod Koul <vinod.koul@intel.com> - 2016-03-08 04:00 +0100
        Re: [PATCH] dma: sun4i: expose block size and wait cycle  configuration to DMA users Vinod Koul <vinod.koul@intel.com> - 2016-03-08 04:00 +0100
          Re: [PATCH] dma: sun4i: expose block size and wait cycle  configuration to DMA users Maxime Ripard <maxime.ripard@free-electrons.com> - 2016-03-08 09:00 +0100
            Re: [linux-sunxi] Re: [PATCH] dma: sun4i: expose block size and wait  cycle configuration to DMA users Hans de Goede <hdegoede@redhat.com> - 2016-03-08 09:50 +0100
              Re: [linux-sunxi] Re: [PATCH] dma: sun4i: expose block size and wait  cycle configuration to DMA users Vinod Koul <vinod.koul@intel.com> - 2016-03-08 11:10 +0100
                Re: [linux-sunxi] Re: [PATCH] dma: sun4i: expose block size and wait  cycle configuration to DMA users Maxime Ripard <maxime.ripard@free-electrons.com> - 2016-03-09 12:20 +0100
            Re: [PATCH] dma: sun4i: expose block size and wait cycle  configuration to DMA users Boris Brezillon <boris.brezillon@free-electrons.com> - 2016-03-08 09:50 +0100
              Re: [linux-sunxi] Re: [PATCH] dma: sun4i: expose block size and  wait cycle configuration to DMA users Priit Laes <plaes@plaes.org> - 2016-03-08 10:20 +0100
              Re: [PATCH] dma: sun4i: expose block size and wait cycle  configuration to DMA users Vinod Koul <vinod.koul@intel.com> - 2016-03-08 11:10 +0100
              Re: [linux-sunxi] Re: [PATCH] dma: sun4i: expose block size and wait  cycle configuration to DMA users LABBE Corentin <clabbe.montjoie@gmail.com> - 2016-03-09 11:10 +0100
            Re: [PATCH] dma: sun4i: expose block size and wait cycle  configuration to DMA users Vinod Koul <vinod.koul@intel.com> - 2016-03-08 11:00 +0100
          Re: [PATCH] dma: sun4i: expose block size and wait cycle  configuration to DMA users Boris Brezillon <boris.brezillon@free-electrons.com> - 2016-03-09 11:20 +0100
            Re: [PATCH] dma: sun4i: expose block size and wait cycle  configuration to DMA users Vinod Koul <vinod.koul@intel.com> - 2016-03-11 07:30 +0100
              Re: [PATCH] dma: sun4i: expose block size and wait cycle  configuration to DMA users Boris Brezillon <boris.brezillon@free-electrons.com> - 2016-03-11 10:50 +0100
                Re: [PATCH] dma: sun4i: expose block size and wait cycle  configuration to DMA users Vinod Koul <vinod.koul@intel.com> - 2016-03-11 11:10 +0100
                Re: [PATCH] dma: sun4i: expose block size and wait cycle  configuration to DMA users Boris Brezillon <boris.brezillon@free-electrons.com> - 2016-03-11 11:30 +0100
                Re: [PATCH] dma: sun4i: expose block size and wait cycle  configuration to DMA users Vinod Koul <vinod.koul@intel.com> - 2016-03-11 12:20 +0100
          Re: [PATCH] dma: sun4i: expose block size and wait cycle  configuration to DMA users Boris Brezillon <boris.brezillon@free-electrons.com> - 2016-03-09 12:30 +0100
            Re: [PATCH] dma: sun4i: expose block size and wait cycle  configuration to DMA users Vinod Koul <vinod.koul@intel.com> - 2016-03-11 07:30 +0100
              Re: [PATCH] dma: sun4i: expose block size and wait cycle  configuration to DMA users Boris Brezillon <boris.brezillon@free-electrons.com> - 2016-03-11 10:50 +0100
                Re: [PATCH] dma: sun4i: expose block size and wait cycle  configuration to DMA users Vinod Koul <vinod.koul@intel.com> - 2016-03-11 11:10 +0100
                Re: [PATCH] dma: sun4i: expose block size and wait cycle  configuration to DMA users Maxime Ripard <maxime.ripard@free-electrons.com> - 2016-03-11 12:00 +0100
                Re: [PATCH] dma: sun4i: expose block size and wait cycle  configuration to DMA users Vinod Koul <vinod.koul@intel.com> - 2016-03-11 12:20 +0100
                Re: [PATCH] dma: sun4i: expose block size and wait cycle  configuration to DMA users Maxime Ripard <maxime.ripard@free-electrons.com> - 2016-03-14 12:50 +0100
                Re: [PATCH] dma: sun4i: expose block size and wait cycle  configuration to DMA users Vinod Koul <vinod.koul@intel.com> - 2016-03-16 04:20 +0100
  Re: [linux-sunxi] [PATCH] dma: sun4i: expose block size and wait  cycle configuration to DMA users Priit Laes <plaes@plaes.org> - 2016-03-07 16:40 +0100
    Re: [linux-sunxi] [PATCH] dma: sun4i: expose block size and wait  cycle configuration to DMA users Boris Brezillon <boris.brezillon@free-electrons.com> - 2016-03-07 17:00 +0100
      Re: [linux-sunxi] [PATCH] dma: sun4i: expose block size and wait  cycle configuration to DMA users Emilio López <emilio@elopez.com.ar> - 2016-03-07 18:20 +0100

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