openwrt/target/linux/ipq40xx/files-4.14/arch
Sven Eckelmann 0d62432834 ipq40xx: Remove unused reserved-memory nodes
The reserved-memory regions are mostly undocumented by QCA and are named
very unspecific in the QSDK device trees. It was tried to clean them up by
commit 71ed9f10a3 ("ipq40xx: Use detailed reserved memory for A42") and
similar changes.

The features which require these regions were mostly unknown but
Senthilkumar N L <snlakshm@qti.qualcomm.com> and Sricharan Ramabadhran
<srichara@qti.qualcomm.com> provided some more insight in some of them:

* crash dump feature
  - a couple of regions used when 'qca,scm_restart_reason' dt node has the
    value 'dload_status' not set to 1
    + apps_bl <0x87000000 0x400000>
    + sbl <0x87400000 0x100000>
    + cnss_debug <0x87400000 0x100000>
    + cpu_context_dump <0x87b00000 0x080000>
  - required driver not available in Linux
  - safe to remove
* QSEE app execution
  - region tz_apps <0x87b80000 0x280000>
  - required driver not available in Linux
  - safe to remove
* communication with TZ/QSEE
  - region smem <0x87b80000 0x280000>
  - driver changes not yet upstreamed
  - must not be removed because any access can crash kernel/program
* trustzone (QSEE) private memory
  - region tz <0x87e80000 0x180000>
  - must not be removed because any access can crash kernel/program

Removing the unnecessary regions saves some kilobyte of reserved-memory and
cleans up the device tree:

* 2560 KiB
  - 8devices Jalapeno
  - AVM FRITZ!Box 4040
  - Compex WPJ428
  - Meraki MR33 Access Point
  - OpenMesh A42
* 14336 KiB
  - GL.iNet GL-B1300
  - Qualcomm Technologies, Inc. IPQ40xx/AP-DK01.1-C1

Signed-off-by: Sven Eckelmann <sven.eckelmann@openmesh.com>
2018-04-20 20:58:52 +02:00
..
arm/boot/dts ipq40xx: Remove unused reserved-memory nodes 2018-04-20 20:58:52 +02:00