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Subject: Re: [PATCH 00/46] Use dmaenginem_async_device_register to simplify
 code
To:     Huang Shijie <sjhuang@iluvatar.ai>, <vkoul@kernel.org>
CC:     <dmaengine@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <dave.jiang@intel.com>, <radhey.shyam.pandey@xilinx.com>,
        <appana.durga.rao@xilinx.com>, <jmkrzyszt@gmail.com>,
        <gomonovych@gmail.com>, <keescook@chromium.org>,
        <horms+renesas@verge.net.au>, <geert+renesas@glider.be>,
        <shawnguo@kernel.org>, <baoyou.xie@linaro.org>,
        <michal.simek@xilinx.com>, <baohua@kernel.org>,
        <ludovic.desroches@microchip.com>, <linus.walleij@linaro.org>,
        <david.brown@linaro.org>
References: <20180803072016.21544-1-sjhuang@iluvatar.ai>
From:   Peter Ujfalusi <peter.ujfalusi@ti.com>
Message-ID: <5d8b222c-6798-aebc-43fc-d4dab9b6f43b@ti.com>
Date:   Fri, 3 Aug 2018 11:20:49 +0300
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Hi,

On 2018-08-03 10:19, Huang Shijie wrote:
> All the patches are using dmaenginem_async_device_register to simplify code
> except the last one:
>   dmaengine: add COMPILE_TEST for the drivers
> 
> I use the last one to do the compiler test.  
> There are still 20 drivers which do not use the dmaenginem_async_device_register.
> Let me take a rest, if this patch set is accepted, I will do the rest.

I think for most of the drivers this series is going to open a race
which is essentially:

prior:
_remove()
{
...
	dma_async_device_register()
	/* Free resources, disable HW, etc */
	return 0;
}

after:
_remove()
{
...
	/* Free resources, disable HW, etc */
	/*
	 * The dma device is still registered and a channel can be
	 * requested
	 */

	dma_async_device_register()
	return 0;
}

It might be theoretical, but conversion to managed device resources is
not straight forward in some cases.

- Péter

> 
> Huang Shijie (46):
>   dmaengine: zx_dma: use dmaenginem_async_device_register to simplify
>     the code
>   dmaengine: zynqmp_dma: use dmaenginem_async_device_register to
>     simplify the code
>   dmaengine: xilinx_dma: use dmaenginem_async_device_register to
>     simplify the code
>   dmaengine: xgene-dma: use dmaenginem_async_device_register to simplify
>     the code
>   dmaengine: txx9dmac: use dmaenginem_async_device_register to simplify
>     the code
>   dmaengine: timb_dma: use dmaenginem_async_device_register to simplify
>     the code
>   dmaengine: omap-dma: use dmaenginem_async_device_register to simplify
>     the code
>   dmaengine: edma: use dmaenginem_async_device_register to simplify the
>     code
>   dmaengine: cppi41: use dmaenginem_async_device_register to simplify
>     the code
>   dmaengine: tegra210-adma: use helper dmaenginem_async_device_register
>   dmaengine: tegra20-apb-dma: use helper
>     dmaenginem_async_device_register
>   dmaengine: sun6i-dma: use helper dmaenginem_async_device_register
>   dmaengine: sun4i-dma: use dmaenginem_async_device_register to simplify
>     the code
>   dmaengine: coh901318: use dmaenginem_async_device_register to simplify
>     the code
>   dmaengine: s3c24xx-dma: use dmaenginem_async_device_register to
>     simplify the code
>   dmaengine: ste_dma40: use dmaenginem_async_device_register to simplify
>     the code
>   dmaengine: stm32-mdma: use dmaenginem_async_device_register to
>     simplify the code
>   dmaengine: stm32-dma: use dmaenginem_async_device_register to simplify
>     the code
>   dmaengine: sprd-dma: use dmaenginem_async_device_register to simplify
>     the code
>   dmaengine: sirf-dma: use dmaenginem_async_device_register to simplify
>     the code
>   dmaengine: bam_dma: use dmaenginem_async_device_register to simplify
>     the code
>   dmaengine: sudmac: use dmaenginem_async_device_register to simplify
>     the code
>   dmaengine: sa11x0-dma: use dmaenginem_async_device_register to
>     simplify the code
>   dmaengine: nbpfaxi: use dmaenginem_async_device_register to simplify
>     the code
>   dmaengine: mmp_tdma: use dmaenginem_async_device_register to simplify
>     the code
>   dmaengine: shdmac: use dmaenginem_async_device_register to simplify
>     the code
>   dmaengine: usb-dmac: use dmaenginem_async_device_register to simplify
>     the code
>   dmaengine: rcar-dmac: use dmaenginem_async_device_register to simplify
>     the code
>   dmaengine: hidma: use dmaenginem_async_device_register to simplify the
>     code
>   dmaengine: pxa_dma: use dmaenginem_async_device_register to simplify
>     the code
>   dmaengine: moxart-dma: use dmaenginem_async_device_register to
>     simplify the code
>   dmaengine: pl330: use dmaenginem_async_device_register to simplify the
>     code
>   dmaengine: pch_dma: use dmaenginem_async_device_register to simplify
>     the code
>   dmaengine: mxs-dma: use dmaenginem_async_device_register to simplify
>     the code
>   dmaengine: mtk-hsdma: use dmaenginem_async_device_register to simplify
>     the code
>   dmaengine: k3dma: use dmaenginem_async_device_register to simplify the
>     code
>   dmaengine: imx-sdma: use dmaenginem_async_device_register to simplify
>     the code
>   dmaengine: imx-dma: use dmaenginem_async_device_register to simplify
>     the code
>   dmaengine: img-mdc-dma: use dmaenginem_async_device_register to
>     simplify the code
>   dmaengine: fsl-edma: use dmaenginem_async_device_register to simplify
>     the code
>   dmaengine: at_hdmac: use dmaenginem_async_device_register to simplify
>     the code
>   dmaengine: at_xdmac: use dmaenginem_async_device_register to simplify
>     the code
>   dmaengine: dma-jz4780: use dmaenginem_async_device_register to
>     simplify the code
>   dmaengine: dma-jz4740: use dmaenginem_async_device_register to
>     simplify the code
>   dmaengine: dma-axi-dmac: use dmaenginem_async_device_register to
>     simplify the code
>   dmaengine: add COMPILE_TEST for the drivers
> 
>  drivers/dma/Kconfig              | 24 ++++++++++++------------
>  drivers/dma/at_hdmac.c           |  4 +---
>  drivers/dma/at_xdmac.c           |  7 ++-----
>  drivers/dma/coh901318.c          | 14 ++++----------
>  drivers/dma/dma-axi-dmac.c       |  7 ++-----
>  drivers/dma/dma-jz4740.c         |  7 ++-----
>  drivers/dma/dma-jz4780.c         |  8 ++------
>  drivers/dma/fsl-edma.c           |  4 +---
>  drivers/dma/img-mdc-dma.c        |  7 ++-----
>  drivers/dma/imx-dma.c            |  8 ++------
>  drivers/dma/imx-sdma.c           |  7 ++-----
>  drivers/dma/k3dma.c              |  7 ++-----
>  drivers/dma/mediatek/mtk-hsdma.c |  4 +---
>  drivers/dma/mmp_tdma.c           |  7 ++-----
>  drivers/dma/moxart-dma.c         |  5 +----
>  drivers/dma/mxs-dma.c            |  3 +--
>  drivers/dma/nbpfaxi.c            |  7 ++-----
>  drivers/dma/pch_dma.c            |  4 +---
>  drivers/dma/pl330.c              |  4 +---
>  drivers/dma/pxa_dma.c            |  3 +--
>  drivers/dma/qcom/bam_dma.c       |  7 ++-----
>  drivers/dma/qcom/hidma.c         |  3 +--
>  drivers/dma/s3c24xx-dma.c        | 11 +++--------
>  drivers/dma/sa11x0-dma.c         |  4 +---
>  drivers/dma/sh/rcar-dmac.c       |  5 +----
>  drivers/dma/sh/shdmac.c          |  5 +----
>  drivers/dma/sh/sudmac.c          |  4 +---
>  drivers/dma/sh/usb-dmac.c        |  3 +--
>  drivers/dma/sirf-dma.c           |  7 ++-----
>  drivers/dma/sprd-dma.c           |  7 ++-----
>  drivers/dma/ste_dma40.c          | 14 +++++---------
>  drivers/dma/stm32-dma.c          |  3 +--
>  drivers/dma/stm32-mdma.c         |  4 +---
>  drivers/dma/sun4i-dma.c          |  7 ++-----
>  drivers/dma/sun6i-dma.c          |  7 ++-----
>  drivers/dma/tegra20-apb-dma.c    |  8 ++------
>  drivers/dma/tegra210-adma.c      |  8 ++------
>  drivers/dma/ti/Kconfig           |  2 +-
>  drivers/dma/ti/cppi41.c          |  7 ++-----
>  drivers/dma/ti/edma.c            |  8 ++------
>  drivers/dma/ti/omap-dma.c        |  5 +----
>  drivers/dma/timb_dma.c           |  3 +--
>  drivers/dma/txx9dmac.c           |  4 +---
>  drivers/dma/xgene-dma.c          | 16 ++--------------
>  drivers/dma/xilinx/xilinx_dma.c  |  5 +----
>  drivers/dma/xilinx/zynqmp_dma.c  |  4 +---
>  drivers/dma/zx_dma.c             |  7 ++-----
>  47 files changed, 88 insertions(+), 221 deletions(-)
> 

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