Re: [PATCH 2/5] spi: bcm2835: Fix controller unregister order

[Andy Shevchenko <andy.shevchenko@xxxxxxxxx>]

On Fri, May 15, 2020 at 7:45 PM Lukas Wunner <lukas@xxxxxxxxx> 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