lkml.org 
[lkml]   [2009]   [Nov]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
SubjectRe: [PATCH] ARM: Add spi controller driver support for NUC900
From
2009/11/19 Andrew Morton <akpm@linux-foundation.org>:
> On Thu, 19 Nov 2009 14:23:49 +0800 Wan ZongShun <mcuos.com@gmail.com> wrote:
>
>> >> +static int __devexit w90p910_spi_remove(struct platform_device *dev)
>> >> +{
>> >> + __ __ struct w90p910_spi *hw = platform_get_drvdata(dev);
>> >> +
>> >> + __ __ platform_set_drvdata(dev, NULL);
>> >> +
>> >> + __ __ spi_unregister_master(hw->master);
>> >> +
>> >> + __ __ clk_disable(hw->clk);
>> >> + __ __ clk_put(hw->clk);
>> >
>> > As far as I can tell, a hardware interrupt could still be pending, or
>> > be under service while the above code is executing?
>> >
>> > If so, I expect bad things will happen?
>>
>> Do you mean that I should put this 'free_irq()' in the front of
>> w90p910_spi_remove___
>>
>> such as:
>> "
>> free_irq(hw->irq, hw);
>>
>> platform_set_drvdata(dev, NULL);
>>
>> spi_unregister_master(hw->master);
>>
>> clk_disable(hw->clk);
>> clk_put(hw->clk);
>
> I don't know, because I don't know what operation the hardware needs to
> stop it from generating interrupts.  Perhaps that's clk_disable()?

The interrupt will be not occur as long as I run clk_disable().

> Once you've stopped the source of interrupts then the code should wait
> for the IRQ handler to complete if it's running on another CPU.  Yes,
> free_irq() does that.

So, regarding my system of single CPU, maybe I need put this
'clk_disable()' in the front of function of w90p910_spi_remove().

right?

> It's only after the clk_disable() and the free_irq() that you can
> guarantee that no interrupt handler will run and attempt to access the
> device and its associated data structures.
>
>



--
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2009-11-19 09:43    [W:0.545 / U:0.040 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site