Hi Steve
On 04/12/2023 21:41, Steve Clevenger wrote:
Hi Suzuki,
On 9/7/2023 2:31 PM, Steve Clevenger wrote:
Hi Suzuki,
On 9/1/2023 5:22 AM, Suzuki K Poulose wrote:
Hi Steve
On 30/08/2023 17:04, Suzuki K Poulose wrote:
Cc: Sudeep
Hi Steve
On 28/08/2023 17:35, Steve Clevenger wrote:
Hi Suzuki,
On 8/27/2023 2:35 PM, Suzuki K Poulose wrote:
Hi Steve
On 26/08/2023 01:14, Steve Clevenger wrote: > > Unfortunately, I tested with the original patch not [PATCH V2]. I've > remedied this. My results below: > > [root@sut01sys-b212 linux]# cat > /sys/devices/system/cpu/cpu123/ARMHC501:23/tmc_etr35/buf_modes_available > auto flat catu > [root@sut01sys-b212 linux]# cat > /sys/devices/system/cpu/cpu123/ARMHC501:23/tmc_etr35/buf_mode_preferred > auto > [root@sut01sys-b212 linux]# echo "catu" > > /sys/devices/system/cpu/cpu123/ARMHC501:23/tmc_etr35/buf_mode_preferred > [root@sut01sys-b212 linux]# cat > /sys/devices/system/cpu/cpu123/ARMHC501:23/tmc_etr35/buf_mode_preferred > catu > > As with the V1 patch, auto defaults to catu. > > I expected to see tmc-sg (former default) as an available mode, but do > not. As I recall, the buffer mode defaulted to ETR scatter-gather > prior > to this patch. Must this capability now be explicitly advertised? I've > seen this done as "arm,scatter-gather" in device trees, but not > used by > Ampere. Perhaps someone can enlighten me.
Yes, you must add that property to the TMC-ETR node (for both DT and ACPI). In the past, almost all of the TMC-ETRs (except Juno board) locked up the system while using the SG mode (due to the interconnect issues, something to do with the transaction). Thus, we decided to add a property explicitly enabling this for a given platform.
When you mentioned, it was using TMC-ETR SG mode, how did you verify this ? Please be aware that the table allocation code etc are shared by both TMC-SG and CATU.
You might recall how this started. I had no way to test the CATU due to the order the ETR modes defaulted (Flat, ETR-SG, CATU). For test purposes, I programmatically swapped the ETR-SG/CATU order and could then verify CATU operation by the driver calling into CATU code. This
So, were you using the DT based boot for the above runs ?
suggests Flat mode was bypassed, and the driver defaulted to ETR-SG prior to this hack. This didn't offer the user any control, hence my feature request. Note that most of the early Ampere self-hosted trace collection used ETR-SG. Now I can't select it.
How is this property described in the ACPI? The "ACPI for CoreSight™ 1.1 Platform Design Document" (DEN0067) doesn't describe this.
This is not specified in the ACPI platform design document. I can get it fixed. Ideally we need a property describing that the scatter-gather mode is safe to use.
Looks like this is not straight forward copying of DT property. We are investigating this on our side and will get back to you.
I noticed this work is queued for 6.7 (coresight-next-6.7). Do you have an update to the ACPI platform design document Ampere can use to base an update so the scatter-gather mode can be used?
I have chased this with the specification team, and we should have something published soon. Apologies for the delay.
Suzuki
Thanks, Steve
The intent behind my request was to have a way to SysFS configure the (available) ETR mode. Unless there's a change to the ACPI, the CATU is the only SG option for Ampere in the near term.
Thanks, Steve
Suzuki
DT uses "arm,scatter-gather" property [0] and this is what we now expect in the ACPI based systems too.
https://elixir.bootlin.com/linux/latest/source/Documentation/devicetree/bind...
Does it sound fine ?
Suzuki
Thanks, Steve
Kind regards Suzuki
> > Steve C. > > On 8/23/2023 4:10 PM, Steve Clevenger wrote: >> >> 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.co... >>>>> >>>>> .../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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Suzuki K Poulose