Messages in this thread | | | Date | Thu, 19 Nov 2009 22:41:51 +0000 | From | Russell King - ARM Linux <> | Subject | Re: [PATCH] ARM: Add spi controller driver support for NUC900 |
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On Thu, Nov 19, 2009 at 05:49:22PM +0800, Wan ZongShun wrote: > 2009/11/19 Russell King - ARM Linux <linux@arm.linux.org.uk>: > > On Thu, Nov 19, 2009 at 04:40:50PM +0800, Wan ZongShun wrote: > >> 2009/11/19 Andrew Morton <akpm@linux-foundation.org>: > >> > 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? > > > > Depending on the hardware, that's not the right answer. If turning off > > the clock also causes register accesses to the device to abort, it is > > a very dangerous thing to do. > > > > It can also be dangerous if the clock is used to synchronise the interrupt > > output - it can lead to the output being permanently asserted if the clock > > is turned off with it asserted. > > > > Normally devices have an "interrupt enable" register. You should disable > > all interrupts from the device using this register after unregistering > > the driver from the (SPI) subsystem. > > sir, so I need implement a API to disable spi device interrupt by > "interrupt enable" register? > but I did not find the operation in other ARM platform when they close > your spi driver. > > or something I missed?
No, I think you need to reverse the effects of w90p910_enable_int() by clearing the ENINT bit. I'm making the assumption that doing so prevents interrupts being generated by the device. -- 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/
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