[PATCH 00/11] coresight: tmc-etr Transparent buffer management

From: Suzuki K Poulose
Date: Fri May 18 2018 - 11:43:31 EST


This series is split of the Coresight ETR perf support patches posted
here [0]. The CATU support and perf backend support will be posted as
separate series for better management and review of the patches.

This series adds the support for TMC ETR Scatter-Gather mode to allow
using physical non-contiguous buffer for holding the trace data. It
also adds a layer to handle the buffer management in a transparent
manner, independent of the underlying mode used by the TMC ETR.
The layer chooses the ETR mode based on different parameters (size,
re-using a set of pages, presence of an SMMU etc.).

Finally we add a sysfs parameter to tune the buffer size for ETR in
sysfs-mode.

During the testing, we found out that if the TMC ETR is not properly
connected to the memory subsystem, the ETR could lock-up the system
while waiting for the "read" transactions to complete in scatter-gather
mode. So, we do not use the mode on a system unless it is safe to do
so. This is specified by a DT property "arm,scatter-gather".

Applies on v4.17-rc4

Changes since v2 in [0] :
- Split the series in [0]
- Address comments on v2
- Rename DT property "scatter-gather" to "arm,scatter-gather"
- Add ETM PID for Cortex-A35, use macros to make the listing easier

[0] - http://lists.infradead.org/pipermail/linux-arm-kernel/2018-May/574875.html

Suzuki K Poulose (11):
coresight: ETM: Add support for Arm Cortex-A73 and Cortex-A35
coresight: tmc: Hide trace buffer handling for file read
coresight: tmc-etr: Do not clean trace buffer
coresight: tmc-etr: Disallow perf mode
coresight: Add helper for inserting synchronization packets
dts: bindings: Restrict coresight tmc-etr scatter-gather mode
dts: juno: Add scatter-gather support for all revisions
coresight: Add generic TMC sg table framework
coresight: Add support for TMC ETR SG unit
coresight: tmc-etr: Add transparent buffer management
coresight: tmc: Add configuration support for trace buffer size

.../ABI/testing/sysfs-bus-coresight-devices-tmc | 8 +
.../devicetree/bindings/arm/coresight.txt | 5 +-
arch/arm64/boot/dts/arm/juno-base.dtsi | 1 +
drivers/hwtracing/coresight/coresight-etb10.c | 12 +-
drivers/hwtracing/coresight/coresight-etm4x.c | 32 +-
drivers/hwtracing/coresight/coresight-priv.h | 10 +-
drivers/hwtracing/coresight/coresight-tmc-etf.c | 45 +-
drivers/hwtracing/coresight/coresight-tmc-etr.c | 1032 ++++++++++++++++++--
drivers/hwtracing/coresight/coresight-tmc.c | 83 +-
drivers/hwtracing/coresight/coresight-tmc.h | 111 ++-
drivers/hwtracing/coresight/coresight.c | 3 +-
11 files changed, 1169 insertions(+), 173 deletions(-)

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