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(-)