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Message-ID: <CA+h21hqC7hAenifvRqbwss=Sr+dAu3H9Dx=UF0TS0WVbkzTj2Q@mail.gmail.com>
Date: Mon, 15 Jun 2020 15:56:01 +0300
From: Vladimir Oltean <olteanv@...il.com>
To: Mark Brown <broonie@...nel.org>
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, 15 Jun 2020 at 15:35, Mark Brown <broonie@...nel.org> wrote:
>
>
> Indeed. The upshot of all this is that the interrupt needs to be freed
> not disabled before the clocks are disabled, or some other mechanism
> needs to be used to ensure that the interrupt handler won't attempt to
> access the hardware when it shouldn't. As Vladimir says there are
> serious issues using devm for interrupt handlers (or anything else that
> might cause code to be run) due to problems like this.
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.
-Vladimir
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