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From: Andy Shevchenko <andy.shevchenko@gmail.com>
To: Lukas Wunner <lukas@wunner.de>
Cc: Mark Brown <broonie@kernel.org>,
	Nicolas Saenz Julienne <nsaenzjulienne@suse.de>,
	Martin Sperl <kernel@martin.sperl.org>,
	linux-spi <linux-spi@vger.kernel.org>,
	linux-rpi-kernel <linux-rpi-kernel@lists.infradead.org>
Subject: Re: [PATCH 2/5] spi: bcm2835: Fix controller unregister order
Date: Sat, 16 May 2020 00:33:00 +0300
Message-ID: <CAHp75Vfs=gc9c2h2amhu0eb3ux8jJAuC7CRY8fLrFiBsTwtSYQ@mail.gmail.com> (raw)
In-Reply-To: <20200515164404.bev4zjzcmx4nwzhi@wunner.de>

On Fri, May 15, 2020 at 7:45 PM Lukas Wunner <lukas@wunner.de> wrote:
> On Fri, May 15, 2020 at 05:29:03PM +0100, Mark Brown wrote:
> > On Fri, May 15, 2020 at 05:58:02PM +0200, Lukas Wunner wrote:
> > > Fix by using the non-devm variant spi_register_controller().  Note that
> > > the struct spi_controller as well as the driver-private data are not
> > > freed until after bcm2835_spi_remove() has finished, so accessing them
> > > is safe.
> >
> > Why not use managed allocations of clocks and DMA channels?  This is a
> > standard issue with the devm APIs, if you're using them you basically
> > need to use them for *everything* up to the point where you start using
> > them.
>
> There is no devm version of clk_prepare_enable(), dma_request_chan()
> and various other functions invoked on ->probe() by spi-bcm2835.c.
> So tearing down DMA channels, disabling clocks etc needs to happen
> in the ->remove() hook and consequently devm_spi_register_controller()
> cannot be used.

There is devm_add_action_or_reset (IIRC the name). It does a trick.


-- 
With Best Regards,
Andy Shevchenko

  reply index

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-15 15:58 [PATCH 0/5] Raspberry Pi SPI unbind fixes Lukas Wunner
2020-05-15 15:58 ` [PATCH 1/5] spi: Fix controller unregister order Lukas Wunner
2020-05-15 16:27   ` Mark Brown
2020-05-15 16:31     ` Lukas Wunner
2020-05-15 21:37       ` Andy Shevchenko
2020-05-16  6:45         ` Lukas Wunner
2020-05-16  9:45           ` Andy Shevchenko
2020-05-15 15:58 ` [PATCH 2/5] spi: bcm2835: " Lukas Wunner
2020-05-15 16:29   ` Mark Brown
2020-05-15 16:44     ` Lukas Wunner
2020-05-15 21:33       ` Andy Shevchenko [this message]
2020-05-16  6:56         ` Lukas Wunner
2020-05-16  9:40           ` Andy Shevchenko
2020-05-15 15:58 ` [PATCH 3/5] spi: bcm2835aux: " Lukas Wunner
2020-05-15 15:58 ` [PATCH 4/5] spi: bcm2835: Tear down DMA before turning off SPI controller Lukas Wunner
2020-05-15 15:58 ` [PATCH 5/5] spi: Document devm_spi_register_controller() gotcha Lukas Wunner
2020-05-15 16:30   ` Mark Brown
2020-05-20 17:17 ` [PATCH 0/5] Raspberry Pi SPI unbind fixes Mark Brown

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