Messages in this thread | | | Date | Fri, 18 Aug 2023 10:39:18 +0100 | Subject | Re: [PATCH V2] coresight: tmc: Make etr buffer mode user configurable from sysfs | From | Suzuki K Poulose <> |
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Cc: Steve
Steve,
Are you able to test this with CATU ?
On 18/08/2023 09:21, Anshuman Khandual wrote: > Currently TMC-ETR automatically selects the buffer mode from all available > methods in the following sequentially fallback manner - also in that order. > > 1. FLAT mode with or without IOMMU > 2. TMC-ETR-SG (scatter gather) mode when available > 3. CATU mode when available > > But this order might not be ideal for all situations. For example if there > is a CATU connected to ETR, it may be better to use TMC-ETR scatter gather > method, rather than CATU. But hard coding such order changes will prevent > us from testing or using a particular mode. This change provides following > new sysfs tunables for the user to control TMC-ETR buffer mode explicitly, > if required. This adds following new sysfs files for buffer mode selection > purpose explicitly in the user space. > > /sys/bus/coresight/devices/tmc_etr<N>/buf_modes_available > /sys/bus/coresight/devices/tmc_etr<N>/buf_mode_preferred > > $ cat buf_modes_available > auto flat tmc-sg catu ------------------> Supported TMC-ETR buffer modes > > $ echo catu > buf_mode_preferred -------> Explicit buffer mode request > > But explicit user request has to be within supported ETR buffer modes only. > These sysfs interface files are exclussive to ETR, and hence these are not > available for other TMC devices such as ETB or ETF etc. > > A new auto' mode (i.e ETR_MODE_AUTO) has been added to help fallback to the > existing default behaviour, when user provided preferred buffer mode fails. > ETR_MODE_FLAT and ETR_MODE_AUTO are always available as preferred modes. > > Cc: Suzuki K Poulose <suzuki.poulose@arm.com> > Cc: Mike Leach <mike.leach@linaro.org> > Cc: James Clark <james.clark@arm.com> > Cc: Leo Yan <leo.yan@linaro.org> > Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> > Cc: coresight@lists.linaro.org > Cc: linux-arm-kernel@lists.infradead.org > Cc: linux-kernel@vger.kernel.org > Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com> > --- > This applies on v6.5-rc6 > > Changes in V2: > > - Renamed sysfs file etr_buf_modes_available as buf_modes_available > - Renamed sysfs file buf_mode_current as buf_mode_preferred > - Renamed etr_supports_flat_mode() as etr_can_use_flat_mode() > - Renamed coresight_tmc_groups[] as coresight_etf_groups[] > - Reused coresight_tmc_group[] for trigger_cntr and buffer_size > - Fallback trying ETR_MODE_AUTO when user preferred mode fails > - Moved ETR sysfs details into coresight-tmc-etr.c > - Dropped etr_can_use_flat_mode() check while offering ETR_MODE_FLAT in sysfs > - Moved struct etr_buf_hw inside coresight-tmc-etr.c > - Moved get_etr_buf_hw() and etr_can_use_flat_mode() inside coresight-tmc-etr.c > - Updated month in Documentation/ABI/testing/sysfs-bus-coresight-devices-tmc > > Changes in V1: > > https://lore.kernel.org/all/20230728084837.276551-1-anshuman.khandual@arm.com/ > > .../testing/sysfs-bus-coresight-devices-tmc | 16 +++ > .../hwtracing/coresight/coresight-tmc-core.c | 15 ++- > .../hwtracing/coresight/coresight-tmc-etr.c | 111 ++++++++++++++++-- > drivers/hwtracing/coresight/coresight-tmc.h | 3 + > 4 files changed, 131 insertions(+), 14 deletions(-)
Looks good to me.
Suzuki
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