On Fri, May 18, 2018 at 05:39:22PM +0100, Suzuki K Poulose wrote: > We are about to add the support for ETR builtin scatter-gather mode > for dealing with large amount of trace buffers. However, on some of > the platforms, using the ETR SG mode can lock up the system due to > the way the ETR is connected to the memory subsystem. > > In SG mode, the ETR performs READ from the scatter-gather table to > fetch the next page and regular WRITE of trace data. If the READ > operation doesn't complete(due to the memory subsystem issues, > which we have seen on a couple of platforms) the trace WRITE > cannot proceed leading to issues. So, we by default do not > use the SG mode, unless it is known to be safe on the platform. > We define a DT property for the TMC node to specify whether we > have a proper SG mode. > > Cc: Mathieu Poirier <[email protected]> > Cc: Mike Leach <[email protected]> > Cc: Mark Rutland <[email protected]> > Cc: John Horley <[email protected]> > Cc: Robert Walker <[email protected]> > Cc: [email protected] > Cc: [email protected] > Cc: Rob Herring <[email protected]> > Signed-off-by: Suzuki K Poulose <[email protected]> > --- > Documentation/devicetree/bindings/arm/coresight.txt | 2 ++ > drivers/hwtracing/coresight/coresight-tmc.c | 9 ++++++++- > 2 files changed, 10 insertions(+), 1 deletion(-)
Reviewed-by: Rob Herring <[email protected]>
