Re: [PATCH 0/7] Add L2 cache cleaning to generic CPU suspend

Lorenzo Pieralisi
2011-09-20T11:45:27Z

On Mon, Sep 19, 2011 at 05:37:41PM +0100, Russell King - ARM Linux wrote:
> This is a re-post of the previous patch series, but with an additional
> TLB flush to ensure that hte global TLB entry in the page tables is
> flushed out. This is a flush of all TLB entries, but it could probably
> be more targetted if we need to.
>
> Original cover mail follows:
>
> Some systems (such as OMAP) preserve the L2 cache across a suspend/
> resume cycle. This means they do not perform L2 cache maintanence
> in their suspend finisher function.
>
> However, the side effect is that the saved CPU state is not readable
> by the resume code because it is sitting in the L2 cache.
>
> This patch series adds L2 cache cleaning to the generic CPU suspend/
> resume support code, making it possible to use this on systems with
> L2 cache enabled without having to clean/invalidate the entire L2
> cache.
>
> We also add a separate page table, allocated at boot time, for the
> resume process to use so we don't have to fiddle about with tweaking
> entries in the current processes page table. Moreover, the current
> processes page table may be in use by another CPU in the system if
> these paths are used from cpuidle or hotplug, so changing the page
> table is technically unsound.
>
> Overall, this makes it possible for OMAP4 systems to use this code.
>
>

Thanks Russell for this.
As expected, it does fix the issue. Tested on ARM internal platforms
and Origen with both suspend and cpuidle. So, on the whole series:

Tested-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>