rapidio: fix blocking wait for discovery ready
The following set of patches provides modifications targeting support of
multiple RapidIO master port (mport) devices on a CPU-side of
RapidIO-capable board. While the RapidIO subsystem code has definitions
suitable for multi-controller/multi-net support, the existing
implementation cannot be considered ready for multiple mport
configurations.
=========== NOTES: =============
a) The patches below do not address RapidIO side view of multiport
processing elements defined in Part 6 of RapidIO spec Rev.2.1 (section
6.4.1). These devices have Base Device ID CSR (0x60) and Component Tag
CSR (0x6C) shared by all SRIO ports. For example, Freescale's P4080,
P3041 and P5020 have a dual-port SRIO controller implemented according
the specification. Enumeration/discovery of such devices from RapidIO
side may require device-specific fixups.
b) Devices referenced above may also require implementation specific
code to setup a host device ID for mport device. These operations are
not addressed by patches in this package.
=================================
Details about provided patches:
1. Fix blocking wait for discovery ready
While it does not happen on PowerPC based platforms, there is
possibility of stalled CPU warning dump on x86 based platforms that run
RapidIO discovery process if they wait too long for being enumerated.
Currently users can avoid it by disabling the soft-lockup detector
using "nosoftlockup" kernel parameter OR by ensuring that enumeration
is completed before soft-lockup is detected.
This patch eliminates blocking wait and keeps a scheduler running.
It also is required for patch 3 below which introduces asynchronous
discovery process.
2. Use device lists handling on per-net basis
This patch allows to correctly support multiple RapidIO nets and
resolves possible issues caused by using single global list of devices
during RapidIO system enumeration/discovery. The most common sign of
existing issue is incorrect contents of switch routing tables in
systems with multiple mport controllers while single-port configuration
performs as expected.
The patch does not eliminate the global RapidIO device list but
changes some routines in enumeration/discovery to use per-net device
lists instead. This way compatibility with upper layer RIO routines is
preserved.
3. Run discovery as an asynchronous process
This patch modifies RapidIO initialization routine to asynchronously
run the discovery process for each corresponding mport. This allows
having an arbitrary order of enumerating and discovering mports without
creating a deadlock situation if an enumerator port was registered
after a discovering one.
On boards with multiple discovering mports it also eliminates order
dependency between mports and may reduce total time of RapidIO
subsystem initialization.
Making netID matching to mportID ensures consistent netID assignment
in multiport RapidIO systems with asynchronous discovery process
(global counter implementation is affected by race between threads).
4. Rework RIONET to support multiple RIO master ports
In the current version of the driver rionet_probe() has comment "XXX
Make multi-net safe". Now it is a good time to address this comment.
This patch makes RIONET driver multi-net safe/capable by introducing
per-net lists of RapidIO network peers. It also enables to register
network adapters for all available mport devices.
5. Add destination ID allocation mechanism
The patch replaces a single global destination ID counter with
per-net allocation mechanism to allow independent destID management for
each available RapidIO network. Using bitmap based mechanism instead
of counters allows destination ID release and reuse in systems that
support hot-swap.
This patch:
Fix blocking wait loop in the RapidIO discovery routine to avoid warning
dumps about stalled CPU on x86 platforms.
Signed-off-by: Alexandre Bounine <alexandre.bounine@idt.com>
Cc: Matt Porter <mporter@kernel.crashing.org>
Cc: Li Yang <leoli@freescale.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 file changed
