Messages in this thread | | | Date | Wed, 23 May 2018 13:18:00 -0500 | From | Rob Herring <> | Subject | Re: [PATCH 06/11] dts: bindings: Restrict coresight tmc-etr scatter-gather mode |
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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 <mathieu.poirier@linaro.org> > Cc: Mike Leach <mike.leach@linaro.org> > Cc: Mark Rutland <mark.rutland@arm.com> > Cc: John Horley <john.horley@arm.com> > Cc: Robert Walker <robert.walker@arm.com> > Cc: devicetree@vger.kernel.org > Cc: frowand.list@gmail.com > Cc: Rob Herring <robh@kernel.org> > Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> > --- > 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 <robh@kernel.org>
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