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authorAchin Gupta <achin.gupta@arm.com>2013-12-05 16:33:10 +0000
committerDan Handley <dan.handley@arm.com>2014-01-20 18:45:04 +0000
commit75f7367b4c5419634004bfae9c1e47ca45937396 (patch)
treeaf71b2527ec14db0996a0371f292df826b971c6f /docs/change-log.md
parenta45e39738bcfb8ad49f581c92c747e159aa23892 (diff)
downloadarm-trusted-firmware-75f7367b4c5419634004bfae9c1e47ca45937396.tar.gz
psci: fix affinity level upgrade issue
The psci implementation does not track target affinity level requests specified during cpu_suspend calls correctly as per the following example. 1. cpu0.cluster0 calls cpu_suspend with the target affinity level as 0 2. Only the cpu0.cluster0 is powered down while cluster0 remains powered up 3. cpu1.cluster0 calls cpu_off to power itself down to highest possible affinity level 4. cluster0 will be powered off even though cpu0.cluster0 does not allow cluster shutdown This patch introduces reference counts at affinity levels > 0 to track the number of cpus which want an affinity instance at level X to remain powered up. This instance can be turned off only if its reference count is 0. Cpus still undergo the normal state transitions (ON, OFF, ON_PENDING, SUSPEND) but the higher levels can only be either ON or OFF depending upon their reference count. The above issue is thus fixed as follows: 1. cluster0's reference count is incremented by two when cpu0 and cpu1 are initially powered on. 2. cpu0.cluster0 calls cpu_suspend with the target affinity level as 0. This does not affect the cluster0 reference count. 3. Only the cpu0.cluster0 is powered down while cluster0 remains powered up as it has a non-zero reference count. 4. cpu1.cluster0 call cpu_off to power itself down to highest possible affinity level. This decrements the cluster0 reference count. 5. cluster0 is still not powered off since its reference count will at least be 1 due to the restriction placed by cpu0. Change-Id: I433dfe82b946f5f6985b1602c2de87800504f7a9
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@@ -104,6 +104,11 @@ Detailed changes since last release
automatically detected by the make file when they are added to the plat
directory.
+* An issue in the PSCI implementation has been fixed which could result in the
+ power down of an affinity instance at level X even though at least one
+ affinity instance at level X - 1 does not allow this.
+
+
ARM Trusted Firmware - version 0.2
==================================