skiboot 5.9.2 release notes

Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>
(cherry picked from commit f37f867)
Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>

doc/release-notes/skiboot-5.9.2.rst

@@ -0,0 +1,80 @@
+.. _skiboot-5.9.2:
+
+=============
+skiboot-5.9.2
+=============
+
+skiboot 5.9.2 was released on Thursday November 16th, 2017. It replaces
+:ref:`skiboot-5.9.1` as the current stable release in the 5.9.x series.
+
+Over :ref:`skiboot-5.9.1`, we have a few PHB4 (PCI) fixes, an i2c fix for
+POWER9 platforms to avoid conflicting with the OCC use and an important
+NPU2 (NVLink2) fix.
+
+- phb4: Fix lane equalisation setting
+
+  Fix cut and paste from phb3. The sizes have changes now we have GEN4,
+  so the check here needs to change also
+
+  Without this we end up with the default settings (all '7') rather
+  than what's in HDAT.
+
+- phb4: Fix PE mapping of M32 BAR
+
+  The M32 BAR is the PHB4 region used to map all the non-prefetchable
+  or 32-bit device BARs. It's supposed to have its segments remapped
+  via the MDT and Linux relies on that to assign them individual PE#.
+
+  However, we weren't configuring that properly and instead used the
+  mode where PE# == segment#, thus causing EEH to freeze the wrong
+  device or PE#.
+- phb4: Fix lost bit in PE number on config accesses
+
+  A PE number can be up to 9 bits, using a uint8_t won't fly..
+
+  That was causing error on config accesses to freeze the
+  wrong PE.
+- phb4: Update inits
+
+  New init value from HW folks for the fence enable register.
+
+  This clears bit 17 (CFG Write Error CA or UR response) and bit 22 (MMIO Write
+  DAT_ERR Indication) and sets bit 21 (MMIO CFG Pending Error)
+- npu2: Move to new GPU memory map
+
+  There are three different ways we configure the MCD and memory map.
+
+  1) Old way (current way)
+     Skiboot configures the MCD and puts GPUs at 4TB and below
+  2) New way with MCD
+     Hostboot configures the MCD and skiboot puts GPU at 4TB and above
+  3) New way without MCD
+     No one configures the MCD and skiboot puts GPU at 4TB and below
+
+  The change keeps option 1 and adds options 2 and 3.
+
+  The different configurations are detected using certain scoms (see
+  patch).
+
+  Option 1 will go away eventually as it's a configuration that can
+  cause xstops or data integrity problems. We are keeping it around to
+  support existing hostboot.
+
+  Option 2 supports only 4 GPUs and 512GB of memory per socket.
+
+  Option 3 supports 6 GPUs and 4TB of memory but may have some
+  performance impact.
+
+- p8-i2c: Don't write the watermark register at init
+
+  On P9 the I2C master is shared with the OCC. Currently the watermark
+  values are set once at init time which is bad for two reasons:
+
+  a) We don't take the OCC master lock before setting it. Which
+     may cause issues if the OCC is currently using the master.
+  b) The OCC might change the watermark levels and we need to reset
+     them.
+
+  Change this so that we set the watermark value when a new transaction
+  is started rather than at init time.
+