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From:   Vladimir Oltean <olteanv@gmail.com>
Date:   Mon, 15 Jun 2020 16:29:15 +0300
Message-ID: <CA+h21hpymKP5JGWZBNQTq4bZwJ6QZ3erACWV86nEaGsevZ++BA@mail.gmail.com>
Subject: Re: [PATCH v2 1/3] spi: spi-fsl-dspi: Fix external abort on interrupt
 in exit paths
To:     Mark Brown <broonie@kernel.org>
Cc:     Marc Kleine-Budde <mkl@pengutronix.de>,
        Krzysztof Kozlowski <krzk@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Vladimir Oltean <vladimir.oltean@nxp.com>,
        linux-spi <linux-spi@vger.kernel.org>,
        lkml <linux-kernel@vger.kernel.org>,
        Wolfram Sang <wsa@kernel.org>, stable@vger.kernel.org,
        Pengutronix Kernel Team <kernel@pengutronix.de>
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On Mon, 15 Jun 2020 at 16:24, Mark Brown <broonie@kernel.org> wrote:
>
> On Mon, Jun 15, 2020 at 04:12:28PM +0300, Vladimir Oltean wrote:
> > On Mon, 15 Jun 2020 at 16:10, Mark Brown <broonie@kernel.org> wrote:
>
> > > It's a bit unusual to need to actually free the IRQ over suspend -
> > > what's driving that requirement here?
>
> > clk_disable_unprepare(dspi->clk); is driving the requirement - same as
> > in dspi_remove case, the module will fault when its registers are
> > accessed without a clock.
>
> I see - this could be fixed by having the interrupt handler bounce the
> clock on, there's a little overhead from that but hopefully not too
> much.  That should also help with the remove case I guess so long as the
> clock is registered before the interrupt is requested?

Doesn't this mean that we risk leaving the clock enabled during suspend?
Is there any function in the SPI core that quiesces any pending
transactions, and then stops the controller? I would have expected
spi_controller_suspend to do that, but I'm not sure (it doesn't look
like it).