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From:   Vladimir Oltean <vladimir.oltean@nxp.com>
To:     Krzysztof Kozlowski <krzk@kernel.org>,
        Mark Brown <broonie@kernel.org>,
        "linux-spi@vger.kernel.org" <linux-spi@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
CC:     "stable@vger.kernel.org" <stable@vger.kernel.org>
Subject: Re: [PATCH] spi: spi-fsl-dspi: Free DMA memory with matching function
Thread-Topic: [PATCH] spi: spi-fsl-dspi: Free DMA memory with matching
 function
Thread-Index: AQHWP0THy/tYaffJNkG7XB6oxxgkvQ==
Date:   Wed, 10 Jun 2020 16:32:49 +0000
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On 6/10/20 6:42 PM, Krzysztof Kozlowski wrote:=0A=
> =0A=
> Driver allocates DMA memory with dma_alloc_coherent() but frees it with=
=0A=
> dma_unmap_single().=0A=
> =0A=
> This causes DMA warning during system shutdown (with DMA debugging) on=0A=
> Toradex Colibri VF50 module:=0A=
> =0A=
>      WARNING: CPU: 0 PID: 1 at ../kernel/dma/debug.c:1036 check_unmap+0x3=
fc/0xb04=0A=
>      DMA-API: fsl-edma 40098000.dma-controller: device driver frees DMA m=
emory with wrong function=0A=
>        [device address=3D0x0000000087040000] [size=3D8 bytes] [mapped as =
coherent] [unmapped as single]=0A=
>      Hardware name: Freescale Vybrid VF5xx/VF6xx (Device Tree)=0A=
>        (unwind_backtrace) from [<8010bb34>] (show_stack+0x10/0x14)=0A=
>        (show_stack) from [<8011ced8>] (__warn+0xf0/0x108)=0A=
>        (__warn) from [<8011cf64>] (warn_slowpath_fmt+0x74/0xb8)=0A=
>        (warn_slowpath_fmt) from [<8017d170>] (check_unmap+0x3fc/0xb04)=0A=
>        (check_unmap) from [<8017d900>] (debug_dma_unmap_page+0x88/0x90)=
=0A=
>        (debug_dma_unmap_page) from [<80601d68>] (dspi_release_dma+0x88/0x=
110)=0A=
>        (dspi_release_dma) from [<80601e4c>] (dspi_shutdown+0x5c/0x80)=0A=
>        (dspi_shutdown) from [<805845f8>] (device_shutdown+0x17c/0x220)=0A=
>        (device_shutdown) from [<80143ef8>] (kernel_restart+0xc/0x50)=0A=
>        (kernel_restart) from [<801441cc>] (__do_sys_reboot+0x18c/0x210)=
=0A=
>        (__do_sys_reboot) from [<80100060>] (ret_fast_syscall+0x0/0x28)=0A=
>      DMA-API: Mapped at:=0A=
>       dma_alloc_attrs+0xa4/0x130=0A=
>       dspi_probe+0x568/0x7b4=0A=
>       platform_drv_probe+0x6c/0xa4=0A=
>       really_probe+0x208/0x348=0A=
>       driver_probe_device+0x5c/0xb4=0A=
> =0A=
> Fixes: 90ba37033cb9 ("spi: spi-fsl-dspi: Add DMA support for Vybrid")=0A=
> Cc: <stable@vger.kernel.org>=0A=
> Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>=0A=
> ---=0A=
=0A=
Sounds reasonable. I always wondered why err_slave_config and =0A=
err_rx_dma_buf call something different than dspi_release_dma, but I =0A=
didn't see any problem so I didn't investigate it further.=0A=
=0A=
Acked-by: Vladimir Oltean <vladimir.oltean@nxp.com>=0A=
=0A=
>   drivers/spi/spi-fsl-dspi.c | 8 ++++----=0A=
>   1 file changed, 4 insertions(+), 4 deletions(-)=0A=
> =0A=
> diff --git a/drivers/spi/spi-fsl-dspi.c b/drivers/spi/spi-fsl-dspi.c=0A=
> index a35faced0456..58190c94561f 100644=0A=
> --- a/drivers/spi/spi-fsl-dspi.c=0A=
> +++ b/drivers/spi/spi-fsl-dspi.c=0A=
> @@ -588,14 +588,14 @@ static void dspi_release_dma(struct fsl_dspi *dspi)=
=0A=
>                  return;=0A=
> =0A=
>          if (dma->chan_tx) {=0A=
> -               dma_unmap_single(dma->chan_tx->device->dev, dma->tx_dma_p=
hys,=0A=
> -                                dma_bufsize, DMA_TO_DEVICE);=0A=
> +               dma_free_coherent(dma->chan_tx->device->dev, dma_bufsize,=
=0A=
> +                                 dma->tx_dma_buf, dma->tx_dma_phys);=0A=
>                  dma_release_channel(dma->chan_tx);=0A=
>          }=0A=
> =0A=
>          if (dma->chan_rx) {=0A=
> -               dma_unmap_single(dma->chan_rx->device->dev, dma->rx_dma_p=
hys,=0A=
> -                                dma_bufsize, DMA_FROM_DEVICE);=0A=
> +               dma_free_coherent(dma->chan_rx->device->dev, dma_bufsize,=
=0A=
> +                                 dma->rx_dma_buf, dma->rx_dma_phys);=0A=
>                  dma_release_channel(dma->chan_rx);=0A=
>          }=0A=
>   }=0A=
> --=0A=
> 2.7.4=0A=
> =0A=
> =0A=
=0A=
Thanks!=0A=
-Vladimir=0A=