[U-Boot] [PATCH 07/15] sunxi_nand_spl: Turn off clocks when we're done with the nand

[Maxime Ripard]

On Thu, Aug 20, 2015 at 08:35:20AM +0200, Hans de Goede wrote:
> On 08/19/2015 03:48 PM, Maxime Ripard wrote:
> >On Sat, Aug 15, 2015 at 10:02:40PM +0200, Hans de Goede wrote:
> >>Turn off the nand and dma clocks when we're done with the nand, this
> >>puts the nand and dma controllers back into a clean state for when the
> >>kernel boots.
> >>
> >>Without this the kernel will not boot properly when it is build with
> >>dma-controller support.
> >
> >The kernel shouldn't behave like that. What issue are you seeing?
> 
> The kernel does not output anything, not even on the serial console,
> so it seems to crash quite early on. I guess that the dma controller
> has an irq asserted and that that fires as soon as the dma driver
> unmasks it.

Hmmm, fishy.

> I did not investigate this further since u-boot really should put
> the hardware in a clean state before booting the os, so we want this
> change even if the kernel were fixed to deal with the unclean state.

I guess we should aim at "fixing" both. The kernel should not really
care about the state the hardware has been left in, and U-boot should
not really leave the dma controller running either.

Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
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