linux-kernel - Re: [RFC] spi: sun6i: disable/unprepare clocks on remove

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Message-ID: <20171206152056.wzhoiphql322mvqw@flea.lan>
Date:   Wed, 6 Dec 2017 16:20:56 +0100
From:   Maxime Ripard <maxime.ripard@...e-electrons.com>
To:     Tobias Jordan <Tobias.Jordan@...ktrobit.com>
Cc:     Mark Brown <broonie@...nel.org>, Chen-Yu Tsai <wens@...e.org>,
        linux-spi@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: Re: [RFC] spi: sun6i: disable/unprepare clocks on remove

Hi Tobias,

On Wed, Dec 06, 2017 at 01:50:29PM +0100, Tobias Jordan wrote:
> sun6i_spi_probe() uses sun6i_spi_runtime_resume() to prepare/enable clocks,
> so sun6i_spi_remove() should use sun6i_spi_runtime_suspend() to
> disable/unprepare them.
> 
> Found by Linux Driver Verification project (linuxtesting.org).
> 
> Fixes: 3558fe900e8af spi: sunxi: Add Allwinner A31 SPI controller driver
> Signed-off-by: Tobias Jordan <Tobias.Jordan@...ktrobit.com>
> ---
> This was found by LDV, and it looks very suspicious to me, but I'm not
> sure if the fix is that easy. Is suspend() called automatically when the
> driver is removed? If not, is it correct to unconditionally call
> suspend(), or should there be a check for the PM state instead?
> 
>  drivers/spi/spi-sun6i.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/spi/spi-sun6i.c b/drivers/spi/spi-sun6i.c
> index fb38234249a8..5e5df09e5d04 100644
> --- a/drivers/spi/spi-sun6i.c
> +++ b/drivers/spi/spi-sun6i.c
> @@ -541,6 +541,7 @@ static int sun6i_spi_probe(struct platform_device *pdev)
>  
>  static int sun6i_spi_remove(struct platform_device *pdev)
>  {
> +	sun6i_spi_runtime_suspend(&pdev->dev);

Yeah, that's not ideal. The best solution would be to call
pm_runtime_force_suspend I guess.

Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

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