Messages in this thread | | | Date | Wed, 23 Aug 2023 16:10:02 -0700 | Subject | Re: [PATCH V2] coresight: tmc: Make etr buffer mode user configurable from sysfs | From | Steve Clevenger <> |
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Here's some quick feedback. My system shows two modes available; auto catu
etr_buf_mode_current is writable. I expected to see tmc-sg (former default) listed in etr_buf_modes_available but it doesn't show up.
Note that both the auto and catu etr_buf_mode_current settings default to catu. My understanding is auto should revert to the default behavior. On my system the default was tmc-sg.
More later.
[root@sut01sys-b212 kernel]# cat /sys/devices/system/cpu/cpu20/ARMHC501\:60/tmc_etr96/etr_buf_modes_available
auto catu [root@sut01sys-b212 kernel]# cat /sys/devices/system/cpu/cpu20/ARMHC501\:60/tmc_etr96/etr_buf_mode_current catu [root@sut01sys-b212 kernel]# echo "catu" > /sys/devices/system/cpu/cpu20/ARMHC501\:60/tmc_etr96/etr_buf_mode_current [root@sut01sys-b212 kernel]# cat /sys/devices/system/cpu/cpu20/ARMHC501\:60/tmc_etr96/etr_buf_mode_current catu
Steve C.
On 8/21/2023 12:40 PM, Steve Clevenger wrote: > > Hi Suzuki, > > I may be able to test it this week. You've already pointed me at the > patch thread(s). The main holdup is I need to merge the 6.6 pending > platform work in order to use the Ampere ACPI. I couldn't get these > patches to apply directly to 6.4 last I tried. > > Steve C. > > On 8/18/2023 2:39 AM, Suzuki K Poulose wrote: >> 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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