linux-kernel - Re: [PATCH v2 1/3] spi: spi-fsl-dspi: Fix external abort on interrupt in exit paths

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Message-ID: <20200615131006.GR4447@sirena.org.uk>
Date:   Mon, 15 Jun 2020 14:10:06 +0100
From:   Mark Brown <broonie@...nel.org>
To:     Vladimir Oltean <olteanv@...il.com>
Cc:     Marc Kleine-Budde <mkl@...gutronix.de>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Vladimir Oltean <vladimir.oltean@....com>,
        linux-spi <linux-spi@...r.kernel.org>,
        lkml <linux-kernel@...r.kernel.org>,
        Wolfram Sang <wsa@...nel.org>, stable@...r.kernel.org,
        Pengutronix Kernel Team <kernel@...gutronix.de>
Subject: Re: [PATCH v2 1/3] spi: spi-fsl-dspi: Fix external abort on
 interrupt in exit paths

On Mon, Jun 15, 2020 at 03:56:01PM +0300, Vladimir Oltean wrote:

> And the down-shot is that whatever is done in dspi_remove (free_irq)
> also needs to be done in dspi_suspend, but with extra care in
> dspi_resume not only to request the irq again, but also to flush the
> module's FIFOs and clear interrupts, because there might have been
> nasty stuff uncaught during sleep:

>     regmap_update_bits(dspi->regmap, SPI_MCR,
>                SPI_MCR_CLR_TXF | SPI_MCR_CLR_RXF,
>                SPI_MCR_CLR_TXF | SPI_MCR_CLR_RXF);
>     regmap_write(dspi->regmap, SPI_SR, SPI_SR_CLEAR);

> So it's pretty messy.

It's a bit unusual to need to actually free the IRQ over suspend -
what's driving that requirement here?  I can see we might need to
reinit the hardware but usually the interrupt handler can be left there
safely.

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