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Subject: Re: [PATCH V3 0/3] Add support for using external dma in SDHCI
To:     Chunyan Zhang <zhang.chunyan@linaro.org>,
        Ulf Hansson <ulf.hansson@linaro.org>,
        Adrian Hunter <adrian.hunter@intel.com>
CC:     <linux-mmc@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        Arnd Bergmann <arnd@arndb.de>, Mark Brown <broonie@kernel.org>,
        Kishon Vijay Abraham I <kishon@ti.com>,
        Sekhar Nori <nsekhar@ti.com>,
        Chunyan Zhang <zhang.lyra@gmail.com>
References: <1543908270-13953-1-git-send-email-zhang.chunyan@linaro.org>
From:   Faiz Abbas <faiz_abbas@ti.com>
Message-ID: <4871e35d-08e4-9199-08bc-f80f83349020@ti.com>
Date:   Tue, 4 Dec 2018 16:06:10 +0530
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Hi Chunyan,

On 04/12/18 12:54 PM, Chunyan Zhang wrote:
> Currently the generic SDHCI code in the Linux kernel supports the SD
> standard DMA integrated into the host controller but does not have any
> support for external DMA controllers implemented using dmaengine meaning
> that custom code is needed for any systems that use a generic DMA
> controller with SDHCI which in practice means any SDHCI controller that
> doesn't have an integrated DMA controller so we should have this as a
> generic feature.
> 
> There are already a number of controller specific drivers that have dmaengine
> code, and some could use sdhci.c actually, but needed to implement mmc_ops->request()
> in their specific driver for sending command with external dma using dmaengine
> framework, with this patchset, them will take advantage of the generic support.
> TI's omap controller is the case as an example.
> 
> Any comments are very appreciated.
> 

Following your comments, I added dmas in dra7.dtsi as shown in the patch
below.

https://pastebin.ubuntu.com/p/J4F3xWZv5c/

This time the MMC devices enumerate successfully but I see a bunch of

[  108.135736] omap-dma-engine 4a056000.dma-controller: t2_desc[10]
allocation failed

messages when I try to run a short ltp test.

https://pastebin.ubuntu.com/p/WvRSkxBPpv/

Thanks,
Faiz