From: Serge Semin <Sergey.Semin@baikalelectronics.ru>
To: Mark Brown <broonie@kernel.org>
Cc: Serge Semin <fancer.lancer@gmail.com>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Vinod Koul <vkoul@kernel.org>, Viresh Kumar <vireshk@kernel.org>,
Dan Williams <dan.j.williams@intel.com>,
Alexey Malahov <Alexey.Malahov@baikalelectronics.ru>,
Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
Paul Burton <paulburton@kernel.org>,
Ralf Baechle <ralf@linux-mips.org>, Arnd Bergmann <arnd@arndb.de>,
Rob Herring <robh+dt@kernel.org>, <linux-mips@vger.kernel.org>,
<devicetree@vger.kernel.org>, <dmaengine@vger.kernel.org>,
<linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 4/6] dmaengine: dw: Print warning if multi-block is unsupported
Date: Mon, 11 May 2020 16:45:02 +0300 [thread overview]
Message-ID: <20200511134502.hjbu5evkiuh75chr@mobilestation> (raw)
In-Reply-To: <20200511115813.GG8216@sirena.org.uk>
On Mon, May 11, 2020 at 12:58:13PM +0100, Mark Brown wrote:
> On Mon, May 11, 2020 at 05:10:16AM +0300, Serge Semin wrote:
>
> > Alas linearizing the SPI messages won't help in this case because the DW DMA
> > driver will split it into the max transaction chunks anyway.
>
> That sounds like you need to also impose a limit on the maximum message
> size as well then, with that you should be able to handle messages up
> to whatever that limit is. There's code for that bit already, so long
> as the limit is not too low it should be fine for most devices and
> client drivers can see the limit so they can be updated to work with it
> if needed.
Hmm, this might work. The problem will be with imposing such limitation through
the DW APB SSI driver. In order to do this I need to know:
1) Whether multi-block LLP is supported by the DW DMA controller.
2) Maximum DW DMA transfer block size.
Then I'll be able to use this information in the can_dma() callback to enable
the DMA xfers only for the safe transfers. Did you mean something like this when
you said "There's code for that bit already" ? If you meant the max_dma_len
parameter, then setting it won't work, because it just limits the SG items size
not the total length of a single transfer.
So the question is of how to export the multi-block LLP flag from DW DMAc
driver. Andy?
-Sergey
next prev parent reply other threads:[~2020-05-11 13:45 UTC|newest]
Thread overview: 72+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-06 13:10 [PATCH 0/5] dmaengine: dw: Take Baikal-T1 SoC DW DMAC peculiarities into account Sergey.Semin
2020-03-06 13:29 ` Andy Shevchenko
2020-03-06 13:30 ` Andy Shevchenko
2020-03-06 13:43 ` Vinod Koul
[not found] ` <20200306135050.40094803087C@mail.baikalelectronics.ru>
2020-03-09 21:45 ` Sergey Semin
[not found] ` <20200306133756.0F74C8030793@mail.baikalelectronics.ru>
2020-03-06 13:47 ` Sergey Semin
2020-03-06 14:11 ` Andy Shevchenko
[not found] ` <20200306141135.9C4F380307C2@mail.baikalelectronics.ru>
2020-03-09 22:08 ` Sergey Semin
2020-05-08 10:52 ` [PATCH v2 0/6] " Serge Semin
2020-05-08 10:52 ` [PATCH v2 1/6] dt-bindings: dma: dw: Convert DW DMAC to DT binding Serge Semin
2020-05-18 17:50 ` Rob Herring
2020-05-08 10:53 ` [PATCH v2 2/6] dt-bindings: dma: dw: Add max burst transaction length property Serge Semin
2020-05-08 11:12 ` Andy Shevchenko
2020-05-11 20:05 ` Serge Semin
2020-05-11 21:01 ` Andy Shevchenko
2020-05-11 21:35 ` Serge Semin
2020-05-12 9:08 ` Andy Shevchenko
2020-05-12 11:49 ` Serge Semin
2020-05-12 12:38 ` Andy Shevchenko
2020-05-15 6:09 ` Vinod Koul
2020-05-15 10:51 ` Andy Shevchenko
2020-05-15 10:56 ` Vinod Koul
2020-05-15 11:11 ` Serge Semin
2020-05-17 17:47 ` Serge Semin
2020-05-18 17:30 ` Rob Herring
2020-05-18 19:30 ` Serge Semin
2020-05-19 17:13 ` Vinod Koul
2020-05-21 1:33 ` Serge Semin
2020-05-08 10:53 ` [PATCH v2 3/6] dmaengine: dw: Set DMA device max segment size parameter Serge Semin
2020-05-08 11:21 ` Andy Shevchenko
2020-05-08 18:49 ` Vineet Gupta
2020-05-11 21:16 ` Serge Semin
2020-05-12 12:35 ` Andy Shevchenko
2020-05-12 17:01 ` Serge Semin
2020-05-15 6:16 ` Vinod Koul
2020-05-15 10:53 ` Andy Shevchenko
2020-05-17 18:22 ` Serge Semin
2020-05-08 10:53 ` [PATCH v2 4/6] dmaengine: dw: Print warning if multi-block is unsupported Serge Semin
2020-05-08 11:26 ` Andy Shevchenko
2020-05-08 11:53 ` Mark Brown
2020-05-08 19:06 ` Andy Shevchenko
2020-05-11 3:13 ` Serge Semin
2020-05-11 14:03 ` Andy Shevchenko
2020-05-11 2:10 ` Serge Semin
2020-05-11 11:58 ` Mark Brown
2020-05-11 13:45 ` Serge Semin [this message]
2020-05-11 13:58 ` Andy Shevchenko
2020-05-11 17:48 ` Mark Brown
2020-05-11 18:25 ` Serge Semin
2020-05-11 19:32 ` Serge Semin
2020-05-11 21:07 ` Andy Shevchenko
2020-05-11 21:08 ` Andy Shevchenko
2020-05-12 12:42 ` Serge Semin
2020-05-15 6:30 ` Vinod Koul
2020-05-17 19:23 ` Serge Semin
2020-05-19 17:02 ` Vinod Koul
2020-05-21 1:40 ` Serge Semin
2020-05-11 17:44 ` Mark Brown
2020-05-11 18:32 ` Serge Semin
2020-05-11 21:32 ` Mark Brown
2020-05-08 10:53 ` [PATCH v2 5/6] dmaengine: dw: Introduce max burst length hw config Serge Semin
2020-05-08 11:41 ` Andy Shevchenko
2020-05-12 14:08 ` Serge Semin
2020-05-12 19:12 ` Andy Shevchenko
2020-05-12 19:47 ` Serge Semin
2020-05-15 11:02 ` Andy Shevchenko
2020-05-15 6:39 ` Vinod Koul
2020-05-17 19:38 ` Serge Semin
2020-05-19 17:07 ` Vinod Koul
2020-05-21 1:47 ` Serge Semin
2020-05-08 10:53 ` [PATCH v2 6/6] dmaengine: dw: Take HC_LLP flag into account for noLLP auto-config Serge Semin
2020-05-08 11:43 ` Andy Shevchenko
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