[PATCH] ARM: psci: boot_secondary: replace __pa with virt_to_idmap

On Thu, Jul 02, 2015 at 11:29:37AM +0100, Mark Rutland wrote:

On Tue, Jun 30, 2015 at 09:25:37PM +0100, Russell King - ARM Linux wrote:

quoted

On Tue, Jun 30, 2015 at 05:18:37PM +0100, Mark Rutland wrote:

quoted

Hi,

On Tue, Jun 30, 2015 at 11:44:22AM +0100, Grygorii Strashko wrote:

quoted

On some PAE systems (e.g. TI Keystone), memory is above the 32-bit
addressable limit, and the interconnect provides an aliased view of
parts of physical memory in the 32-bit addressable space. This alias
is strictly for boot time usage, and is not otherwise usable because
of coherency limitations.

On such systems, the idmap mechanism has to be used to pass correct
boot address of secondary CPU to FW.
virt_to_idmap() will fall-back to existing virt_to_phys() macro if
such conversation is not required.

Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Nicolas Pitre <redacted>
Cc: Santosh Shilimkar <ssantosh@kernel.org>
Cc: Vitaly Andrianov <redacted>
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
---
 arch/arm/kernel/psci_smp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

The code itself looks sane to me, though the commit message would be
better with Russell's suggested rewording.

This will also conflict with my migration to a common PSCI client
implementation [1,2] (especially given the absence of virt_to_idmap on
arm64), but I'm happy to fold it in or rebase atop of it.

Russell, are you able to take a look at the migration patch [2]? How
would you prefer for the two patches to be taken?

Well, the first thing that stands out about patch [2] is that it's
introducing a load of magic hex numbers, where before we had a struct
with nice definitions.  (I'm thinking about highbank_suspend_finish()
and calxeda_idle_finish().)  This seems to be a backwards step.

The existing suspend parameter packing/unpacking didn't work now that
there are multiple possible formats for the suspend parameter from
PSCIv1.0 onwards, and the core PSCI code won't do any more
packing/unpacking, treating the suspend parameter as a mostly opaque
token.

... which is fine.

I could retain the struct and packing functions for the two cases you
mention, but it seemed somewhat misleading. I'll see if I can figure out
something better than a raw hex value.

What's wrong with a few #defines for this?  It obviously is well enough
defined in existing pre-v1.0 implementations as there is an existing
structure to the parameter.

Can we not do something like:

#define PSCI_POWER_STATE_ID(x)			(x)
#define PSCI_POWER_STATE_TYPE_POWER_DOWN	0x000100000
#define PSCI_POWER_STATE_AFFINITY_LEVEL(x)	((x) << 24)

?

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