android_kernel_xiaomi_sm8350/drivers/firewire
Stefan Richter 168cf9af69 firewire: remove incomplete Bus_Time CSR support
The current implementation of Bus_Time read access was buggy since it
did not ensure that Bus_Time.second_count_hi and second_count_lo came
from the same 128 seconds period.

Reported-by: Håkan Johansson <f96hajo@chalmers.se>

Instead of a fix, remove Bus_Time register support altogether.  The spec
requires all cycle master capable nodes to implement this (all Linux
nodes are cycle master capable) while it also says that it "may" be
initialized by the bus manager or by the IRM standing in for a bus
manager.  (Neither Linux' firewire-core nor ieee1394 nodemgr implement
this.)

Since we cannot rely on Bus_Time having been initialized by a bus
manager, it is better to return an error instead of a nonsensical value
on a read request to Bus_Time.

Alternatively, we could fix the Bus_Time read integrity bug _and_
implement (a) cycle master's write support of the register as well as
(b) bus manager's Bus_Time initialization service, i.e. preservation of
the Bus_Time when the cycle master node of a bus changes.  However, that
would be quite some code for a feature that is unreliable to begin with
and very likely unused in practice.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
2010-02-20 22:33:14 +01:00
..
core-card.c firewire: core: optimize Topology Map creation 2009-10-14 23:10:48 +02:00
core-cdev.c firewire: remove incomplete Bus_Time CSR support 2010-02-20 22:33:14 +01:00
core-device.c firewire: qualify config ROM cache pointers as const pointers 2009-12-29 19:58:17 +01:00
core-iso.c firewire: core: fix crash in iso resource management 2009-09-05 15:59:34 +02:00
core-topology.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2009-12-09 19:43:33 -08:00
core-transaction.c firewire: remove incomplete Bus_Time CSR support 2010-02-20 22:33:14 +01:00
core.h firewire: remove incomplete Bus_Time CSR support 2010-02-20 22:33:14 +01:00
Kconfig firewire, ieee1394: update Kconfig help 2009-12-29 19:58:17 +01:00
Makefile
net.c drivers: Kill now superfluous ->last_rx stores 2009-09-02 23:07:36 -07:00
ohci.c firewire: remove incomplete Bus_Time CSR support 2010-02-20 22:33:14 +01:00
ohci.h
sbp2.c firewire: qualify config ROM cache pointers as const pointers 2009-12-29 19:58:17 +01:00