linux-kernel - Re: [PATCH v4 1/4] spi: spi-fsl-dspi: Fix lockup if device is removed during SPI transfer

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Date:   Mon, 22 Jun 2020 14:17:26 +0300
From:   Vladimir Oltean <olteanv@...il.com>
To:     Krzysztof Kozlowski <krzk@...nel.org>
Cc:     Mark Brown <broonie@...nel.org>, Peng Ma <peng.ma@....com>,
        linux-spi <linux-spi@...r.kernel.org>,
        lkml <linux-kernel@...r.kernel.org>,
        Vladimir Oltean <vladimir.oltean@....com>,
        Wolfram Sang <wsa@...nel.org>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        stable@...r.kernel.org
Subject: Re: [PATCH v4 1/4] spi: spi-fsl-dspi: Fix lockup if device is removed
 during SPI transfer

On Mon, 22 Jun 2020 at 14:06, Krzysztof Kozlowski <krzk@...nel.org> wrote:
>
> During device removal, the driver should unregister the SPI controller
> and stop the hardware.  Otherwise the dspi_transfer_one_message() could
> wait on completion infinitely.
>
> Additionally, calling spi_unregister_controller() first in device
> removal reverse-matches the probe function, where SPI controller is
> registered at the end.
>
> Fixes: 05209f457069 ("spi: fsl-dspi: add missing clk_disable_unprepare() in dspi_remove()")
> Cc: <stable@...r.kernel.org>
> Reported-by: Vladimir Oltean <olteanv@...il.com>
> Signed-off-by: Krzysztof Kozlowski <krzk@...nel.org>
>
> ---

Reviewed-by: Vladimir Oltean <vladimir.oltean@....com>
Tested-by: Vladimir Oltean <vladimir.oltean@....com>

>
> Changes since v3:
> 1. New patch.
> ---
>  drivers/spi/spi-fsl-dspi.c | 11 ++++++++++-
>  1 file changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/spi/spi-fsl-dspi.c b/drivers/spi/spi-fsl-dspi.c
> index 58190c94561f..ec0fd0d366eb 100644
> --- a/drivers/spi/spi-fsl-dspi.c
> +++ b/drivers/spi/spi-fsl-dspi.c
> @@ -1434,9 +1434,18 @@ static int dspi_remove(struct platform_device *pdev)
>         struct fsl_dspi *dspi = spi_controller_get_devdata(ctlr);
>
>         /* Disconnect from the SPI framework */
> +       spi_unregister_controller(dspi->ctlr);
> +
> +       /* Disable RX and TX */
> +       regmap_update_bits(dspi->regmap, SPI_MCR,
> +                          SPI_MCR_DIS_TXF | SPI_MCR_DIS_RXF,
> +                          SPI_MCR_DIS_TXF | SPI_MCR_DIS_RXF);
> +
> +       /* Stop Running */
> +       regmap_update_bits(dspi->regmap, SPI_MCR, SPI_MCR_HALT, SPI_MCR_HALT);
> +
>         dspi_release_dma(dspi);
>         clk_disable_unprepare(dspi->clk);
> -       spi_unregister_controller(dspi->ctlr);
>
>         return 0;
>  }
> --
> 2.17.1
>