[PATCH v2 2/4] dmaengine: Add STM32 DMA driver

M'boumba Cedric Madianga cedric.madianga at gmail.com
Wed Oct 14 08:26:04 PDT 2015

2015-10-14 16:24 GMT+02:00 Daniel Thompson <daniel.thompson at linaro.org>:
> Hmnnn...
> The dmaengine framework will WARN_ONCE() if an dmaengine is removed whilst
> it is active and also works hard to ensure dmaengine modules are not removed
> whilst there are active drivers using the framework.
> How do we get into this function whilst there is still an active DMA
> channels?

For example, when a user try "rmmod stm32-dma" in uart console.
It will enter in stm32_dma_remove while there is potentially still active DMA.

>> But even with this improvement, I think I have to disable the clock here.
> As above, I think the dmaengine framework work to protect you from this sort
> problem. However even if I am wrong about that then unconditionally calling
> clk_disable_unprepare() can not be used to reliably manage the clocks. You
> don't know what the counts are!

Ok got it. Thanks for the clarification.


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