CoreSight

coresight@lists.linaro.org

6 participants
2649 discussions

Failed for ETM decoding with db410c snapshot mode

by leo.yan＠linaro.org

Hi Mike, Mathieu, [ + CoreSight ML ] When I work on the CoreSight + perf tool and used crash extension program to extract the tracing data from perf aux buffer, finally I can get the trace data for about 1.6MB from ETF sink from DB410c board. To verify the extracted trace data, I used 'snapshot' mode under OpenCSD code base, you could see the tar file for this [1]. After you download this file, you could place it under OpenCSD folder: $ cp db410c_snapshot_kdump.tgz my_opencsd/decoder/tests/snapshots $ cd my_opencsd/decoder/tests/snapshots $ tar zxvf db410c_snapshot_kdump.tgz $ cd db410c_snapshot_kdump $ ../../bin/builddir/trc_pkt_lister $ ../../bin/builddir/trc_pkt_lister -decode If I use the command 'trc_pkt_lister' without any extra options, it can print out trace packets successfully; but if I add the extra option '-decode' it uses 'decode all' mode and it reports the errors as: 483710 Idx:53086; ID:10; [0xf8 ]; I_ATOM_F3 : Atom format 3.; NNN 483711 Idx:53086; ID:10; OCSD_GEN_TRC_ELEM_ADDR_NACC( 0xffff000008abc9f0 ) 483712 Idx:53088; ID:10; [0xdb ]; I_ATOM_F2 : Atom format 2.; EE 483713 Idx:53194; ID:10; [0x6b 0x8c 0x08 0xfa 0xdc 0x95 0x5c ]; I_COND_RES_F1 : Conditional Result, format 1. 483714 DCD_ETMV4_0016 : 0x0018 (OCSD_ERR_BAD_DECODE_PKT) [Reserved or unknown packet in decoder.]; Unsupported packet type.Trace Packet Lister : Data Path fatal error 483715 0x0018 (OCSD_ERR_BAD_DECODE_PKT) [Reserved or unknown packet in decoder.]; Unsupported packet type.Trace Packet Lister : Trace buffer done, processed 53216 bytes. You also could check detailed log trc_pkt_lister.ppl in the shared tar packet; After searched for the OpenCSD code and found this error is due it cannot support some types of packets [2]. So want to check what's the best for this issue; seems to me we need to fix this so it can support well to complete the decoding? Thanks in advance for suggestion. Leo Yan [1] http://people.linaro.org/~leo.yan/opencsd_db410c/db410c_snapshot_kdump.tgz [2] https://github.com/Linaro/OpenCSD/blob/master/decoder/source/etmv4/trc_pkt_…

7 years, 6 months

Decoding STM traces with OpenCSD test programs

by Mathieu Poirier

Good day Leo, Please meet my new friend Christophe. He is from ST-Micro and is currently working on integrating the CS framework in their next platform. I would be grateful if you could share with him the instructions you have used to get STM doing on the dragon board and how you got the snapshot decoder to decode the traces. Christophe is also looking to get a trace snapshot that is known to be working properly to test in his environment. Many thanks, Mathieu

7 years, 6 months

[PATCH] perf: Support for Arm A32/T32 instruction sets in CoreSight trace

by Robert Walker

This patch adds support for generating instruction samples from trace of AArch32 programs using the A32 and T32 instruction sets. T32 has variable 2 or 4 byte instruction size, so the conversion between addresses and instruction counts requires extra information from the trace decoder, requiring version 0.9.1 of OpenCSD. A check for the new struct member has been added to the feature check for OpenCSD. Signed-off-by: Robert Walker <robert.walker(a)arm.com> --- tools/build/feature/test-libopencsd.c | 7 +++ tools/perf/util/cs-etm-decoder/cs-etm-decoder.c | 27 ++++++++++ tools/perf/util/cs-etm-decoder/cs-etm-decoder.h | 10 ++++ tools/perf/util/cs-etm.c | 71 +++++++++++-------------- 4 files changed, 75 insertions(+), 40 deletions(-) diff --git a/tools/build/feature/test-libopencsd.c b/tools/build/feature/test-libopencsd.c index 5ff1246..d96b2df 100644 --- a/tools/build/feature/test-libopencsd.c +++ b/tools/build/feature/test-libopencsd.c @@ -3,6 +3,13 @@ int main(void) { + /* + * Requires ocsd_generic_trace_elem.num_instr_range introduced in + * OpenCSD 0.9 + */ + ocsd_generic_trace_elem elem; + (void)elem.num_instr_range; + (void)ocsd_get_version(); return 0; } diff --git a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c index 938def6..73d8384 100644 --- a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c +++ b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c @@ -263,9 +263,12 @@ static void cs_etm_decoder__clear_buffer(struct cs_etm_decoder *decoder) decoder->tail = 0; decoder->packet_count = 0; for (i = 0; i < MAX_BUFFER; i++) { + decoder->packet_buffer[i].isa = CS_ETM_ISA_UNKNOWN; decoder->packet_buffer[i].start_addr = CS_ETM_INVAL_ADDR; decoder->packet_buffer[i].end_addr = CS_ETM_INVAL_ADDR; + decoder->packet_buffer[i].instr_count = 0; decoder->packet_buffer[i].last_instr_taken_branch = false; + decoder->packet_buffer[i].last_instr_size = 0; decoder->packet_buffer[i].exc = false; decoder->packet_buffer[i].exc_ret = false; decoder->packet_buffer[i].cpu = INT_MIN; @@ -294,11 +297,13 @@ cs_etm_decoder__buffer_packet(struct cs_etm_decoder *decoder, decoder->packet_count++; decoder->packet_buffer[et].sample_type = sample_type; + decoder->packet_buffer[et].isa = CS_ETM_ISA_UNKNOWN; decoder->packet_buffer[et].exc = false; decoder->packet_buffer[et].exc_ret = false; decoder->packet_buffer[et].cpu = *((int *)inode->priv); decoder->packet_buffer[et].start_addr = CS_ETM_INVAL_ADDR; decoder->packet_buffer[et].end_addr = CS_ETM_INVAL_ADDR; + decoder->packet_buffer[et].instr_count = 0; if (decoder->packet_count == MAX_BUFFER - 1) return OCSD_RESP_WAIT; @@ -321,8 +326,28 @@ cs_etm_decoder__buffer_range(struct cs_etm_decoder *decoder, packet = &decoder->packet_buffer[decoder->tail]; + switch (elem->isa) { + case ocsd_isa_aarch64: + packet->isa = CS_ETM_ISA_A64; + break; + case ocsd_isa_arm: + packet->isa = CS_ETM_ISA_A32; + break; + case ocsd_isa_thumb2: + packet->isa = CS_ETM_ISA_T32; + break; + case ocsd_isa_tee: + case ocsd_isa_jazelle: + case ocsd_isa_custom: + case ocsd_isa_unknown: + default: + packet->isa = CS_ETM_ISA_UNKNOWN; + } + packet->start_addr = elem->st_addr; packet->end_addr = elem->en_addr; + packet->instr_count = elem->num_instr_range; + switch (elem->last_i_type) { case OCSD_INSTR_BR: case OCSD_INSTR_BR_INDIRECT: @@ -336,6 +361,8 @@ cs_etm_decoder__buffer_range(struct cs_etm_decoder *decoder, break; } + packet->last_instr_size = elem->last_instr_sz; + return ret; } diff --git a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.h b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.h index 612b575..9a10eda 100644 --- a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.h +++ b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.h @@ -28,11 +28,21 @@ enum cs_etm_sample_type { CS_ETM_TRACE_ON = 1 << 1, }; +enum cs_etm_isa { + CS_ETM_ISA_UNKNOWN, + CS_ETM_ISA_A64, + CS_ETM_ISA_A32, + CS_ETM_ISA_T32, +}; + struct cs_etm_packet { enum cs_etm_sample_type sample_type; + enum cs_etm_isa isa; u64 start_addr; u64 end_addr; + u64 instr_count; u8 last_instr_taken_branch; + u8 last_instr_size; u8 exc; u8 exc_ret; int cpu; diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c index 2ae6402..579f52a 100644 --- a/tools/perf/util/cs-etm.c +++ b/tools/perf/util/cs-etm.c @@ -31,14 +31,6 @@ #define MAX_TIMESTAMP (~0ULL) -/* - * A64 instructions are always 4 bytes - * - * Only A64 is supported, so can use this constant for converting between - * addresses and instruction counts, calculting offsets etc - */ -#define A64_INSTR_SIZE 4 - struct cs_etm_auxtrace { struct auxtrace auxtrace; struct auxtrace_queues queues; @@ -492,21 +484,16 @@ static inline void cs_etm__reset_last_branch_rb(struct cs_etm_queue *etmq) etmq->last_branch_rb->nr = 0; } -static inline u64 cs_etm__last_executed_instr(struct cs_etm_packet *packet) -{ - /* Returns 0 for the CS_ETM_TRACE_ON packet */ - if (packet->sample_type == CS_ETM_TRACE_ON) - return 0; +static inline int cs_etm__t32_instr_size(struct cs_etm_queue *etmq, + u64 addr) { + u8 instrBytes[2]; - /* - * The packet records the execution range with an exclusive end address - * - * A64 instructions are constant size, so the last executed - * instruction is A64_INSTR_SIZE before the end address - * Will need to do instruction level decode for T32 instructions as - * they can be variable size (not yet supported). + cs_etm__mem_access(etmq, addr, 2, instrBytes); + /* T32 instruction size is indicated by bits[15:11] of the first + * 16-bit word of the instruction: 0b11101, 0b11110 and 0b11111 + * denote a 32-bit instruction. */ - return packet->end_addr - A64_INSTR_SIZE; + return ((instrBytes[1] & 0xF8) >= 0xE8) ? 4 : 2; } static inline u64 cs_etm__first_executed_instr(struct cs_etm_packet *packet) @@ -518,27 +505,32 @@ static inline u64 cs_etm__first_executed_instr(struct cs_etm_packet *packet) return packet->start_addr; } -static inline u64 cs_etm__instr_count(const struct cs_etm_packet *packet) +static inline +u64 cs_etm__last_executed_instr(const struct cs_etm_packet *packet) { - /* - * Only A64 instructions are currently supported, so can get - * instruction count by dividing. - * Will need to do instruction level decode for T32 instructions as - * they can be variable size (not yet supported). - */ - return (packet->end_addr - packet->start_addr) / A64_INSTR_SIZE; + /* Returns 0 for the CS_ETM_TRACE_ON packet */ + if (packet->sample_type == CS_ETM_TRACE_ON) + return 0; + + return packet->end_addr - packet->last_instr_size; } -static inline u64 cs_etm__instr_addr(const struct cs_etm_packet *packet, +static inline u64 cs_etm__instr_addr(struct cs_etm_queue *etmq, + const struct cs_etm_packet *packet, u64 offset) { - /* - * Only A64 instructions are currently supported, so can get - * instruction address by muliplying. - * Will need to do instruction level decode for T32 instructions as - * they can be variable size (not yet supported). - */ - return packet->start_addr + offset * A64_INSTR_SIZE; + if (packet->isa == CS_ETM_ISA_T32) { + u64 addr = packet->start_addr; + + while (offset > 0) { + addr += cs_etm__t32_instr_size(etmq, addr); + offset--; + } + return addr; + } + + /* Assume a 4 byte instruction size (A32/A64) */ + return packet->start_addr + offset * 4; } static void cs_etm__update_last_branch_rb(struct cs_etm_queue *etmq) @@ -867,9 +859,8 @@ static int cs_etm__sample(struct cs_etm_queue *etmq) struct cs_etm_auxtrace *etm = etmq->etm; struct cs_etm_packet *tmp; int ret; - u64 instrs_executed; + u64 instrs_executed = etmq->packet->instr_count; - instrs_executed = cs_etm__instr_count(etmq->packet); etmq->period_instructions += instrs_executed; /* @@ -899,7 +890,7 @@ static int cs_etm__sample(struct cs_etm_queue *etmq) * executed, but PC has not advanced to next instruction) */ u64 offset = (instrs_executed - instrs_over - 1); - u64 addr = cs_etm__instr_addr(etmq->packet, offset); + u64 addr = cs_etm__instr_addr(etmq, etmq->packet, offset); ret = cs_etm__synth_instruction_sample( etmq, addr, etm->instructions_sample_period); -- 2.7.4

7 years, 6 months

хпфн

by всэ

цхэ гхжщ мюма

7 years, 7 months

[PATCH v3 00/13] coresight: perf: Support for TMC ETR backend

by Suzuki K Poulose

This series adds the support for using the tmc-etr in perf mode for storing the trace to system RAM. The ETR uses a separate buffer (double buffering) for storing the trace. This is copied back to the ring buffer when the event is stopped. We try to match the ETR buffer to the larger of perf ring buffer or the size configured for the ETR via sysfs. This allows tuning the buffer size to prevent overflows and loosing trace data, as we don't have overflow interrupt support (yet). Applies on coresight/next Changes since v2: - Split hotplug lock cleanup from per-cpu path management - Add support for tracing on hotplugged CPUs (based on patch by Mathieu) - Fix handling of perf mode in etb10 driver - Fix CS_UNLOCK() typo in ETR perf driver - Rename call backs from tmc_etr_<op>_perf_buffer => tmc_<op>_etr_buffer to be consistent with ETF driver - Modify the commit description for removing set_buffer call back. Changes since v1 : - Fix path for each CPU where the event might be recorded. - Handle errors in enabling source - Remove set_buffer callback to avoid complicating the error handling. - Fix a bug in handling sysfs mode specific buffers Changes since [0] : - Drop buffer rotation logic for etr-buf - Do not use perf ring buffer. (Add support later) - Fix handling of sink, preventing mixed modes of operation. [0] - TMC ETR perf support - http://lists.infradead.org/pipermail/linux-arm-kernel/2018-May/574875.html Suzuki K Poulose (13): coresight: Fix handling of sinks coresight: etb10: Fix handling of perf mode coresight: perf: Fix per cpu path management coresight: perf: Avoid unncessary CPU hotplug read lock coresight: perf: Allow tracing on hotplugged CPUs coresight: perf: Disable trace path upon source error coresight: tmc-etr: Handle driver mode specific ETR buffers coresight: tmc-etr: Relax collection of trace from sysfs mode coresight: Convert driver messages to dev_dbg coresight: perf: Remove reset_buffer call back for sinks coresight: perf: Add helper to retrieve sink configuration coresight: perf: Remove set_buffer call back coresight: etm-perf: Add support for ETR backend .../coresight/coresight-dynamic-replicator.c | 4 +- drivers/hwtracing/coresight/coresight-etb10.c | 100 +++---- drivers/hwtracing/coresight/coresight-etm-perf.c | 134 +++++---- drivers/hwtracing/coresight/coresight-etm-perf.h | 26 ++ drivers/hwtracing/coresight/coresight-etm3x.c | 4 +- drivers/hwtracing/coresight/coresight-etm4x.c | 4 +- drivers/hwtracing/coresight/coresight-funnel.c | 4 +- drivers/hwtracing/coresight/coresight-priv.h | 2 +- drivers/hwtracing/coresight/coresight-replicator.c | 4 +- drivers/hwtracing/coresight/coresight-stm.c | 4 +- drivers/hwtracing/coresight/coresight-tmc-etf.c | 94 +++--- drivers/hwtracing/coresight/coresight-tmc-etr.c | 327 ++++++++++++++++++--- drivers/hwtracing/coresight/coresight-tmc.c | 4 +- drivers/hwtracing/coresight/coresight-tmc.h | 4 + drivers/hwtracing/coresight/coresight-tpiu.c | 6 +- drivers/hwtracing/coresight/coresight.c | 31 +- include/linux/coresight.h | 12 +- 17 files changed, 517 insertions(+), 247 deletions(-) -- 2.7.4

7 years, 7 months

New Version of OpenCSD Library 0.9.1

by Mike Leach

New version of the library has been released. Fixes issue raised where a segfault can occur in the memory caching code if the first memory location the decoder attempts to access does not have an associated memory image registered with the library -- Mike Leach Principal Engineer, ARM Ltd. Manchester Design Centre. UK

7 years, 7 months

[PATCH v2 00/10] coresight: Update device tree bindings

by Suzuki K Poulose

Coresight uses DT graph bindings to describe the connections of the components. However we have some undocumented usage of the bindings to describe some of the properties of the connections. The coresight driver needs to know the hardware ports invovled in the connection and the direction of data flow to effectively manage the trace sessions. So far we have relied on the "port" address (as described by the generic graph bindings) to represent the hardware port of the component for a connection. The hardware uses separate numbering scheme for input and output ports, which implies, we could have two different (input and output) ports with the same port number. This could create problems in the graph bindings where the label of the port wouldn't match the address. e.g, with the existing bindings we get : port@0{ // Output port 0 reg = <0>; ... }; port@1{ reg = <0>; // Input port 0 endpoint { slave-mode; ... }; }; With the new enforcement in the DT rules, mismatches in label and address are not allowed (as see in the case for port@1). So, we need a new mechanism to describe the hardware port number reliably. Also, we relied on an undocumented "slave-mode" property (see the above example) to indicate if the port is an input port. Let us formalise and switch to a new property to describe the direction of data flow. There were three options considered for the hardware port number scheme: 1) Use natural ordering in the DT to infer the hardware port number. i.e, Mandate that the all ports are listed in the DT and in the ascending order for each class (input and output respectively). Pros : - We don't need new properties and if the existing DTS list them in order (which most of them do), they work out of the box. Cons : - We must list all the ports even if the system cannot/shouldn't use it. - It is prone to human errors (if the order is not kept). 2) Use an explicit property to list both the direction and the hw port number and direction. Define "coresight,hwid" as 2 member array of u32, where the members are port number and the direction respectively. e.g port@0{ reg = <0>; endpoint { coresight,hwid = <0 1>; // Port # 0, Output } }; port@1{ reg = <1>; endpoint { coresight,hwid = <0 0>; // Port # 0, Input }; }; Pros: - The bindings are formal but not so reader friendly and could potentially lead to human errors. Cons: - Backward compatiblity is lost. 3) Use explicit properties (implemented in the series) for the hardware port id and direction. We define a new property "coresight,hwid" for each endpoint in coresight devices to specify the hardware port number explicitly. Also use a separate property "direction" to specify the direction of the data flow. e.g, port@0{ reg = <0>; endpoint { direction = <1>; // Output coresight,hwid = <0>; // Port # 0 } }; port@1{ reg = <1>; endpoint { direction = <0>; // Input coresight,hwid = <0>; // Port # 0 }; }; Pros: - The bindings are formal and reader friendly, and less prone to errors. Cons: - Backward compatibility is lost. After a round of discussions [1], the following option (4) is adopted : 4) Group ports based on the directions under a dedicated node. This has been checked with the upstream DTC tool to resolve the "address mismatch" issue. e.g, out-ports { // Output ports for this component port@0 { // Outport 0 reg = 0; endpoint { ... }; }; port@1 { // Outport 1 reg = 1; endpoint { ... }; }; }; in-ports { // Input ports for this component port@0 { // Inport 0 reg = 0; endpoint { ... }; }; port@1 { // Inport 1 reg = 1; endpoint { ... }; }; }; This series implements Option (4) listed above and falls back to the old bindings if the new bindings are not available. This allows the systems with old bindings work with the new driver. The driver now issues a warning (once) when it encounters the old bindings. The series contains DT update for Juno platform. The remaining in-kernel sources could be updated once we are fine with the proposal. It also cleans up the platform parsing code to reduce the memory usage by reusing the platform description. Applies on coresight/next Changes since V1: - Implement the proposal by Rob. - Drop the DTS updates for all platforms except Juno - Drop the incorrect fix in coresight_register. Instead document the code to prevent people trying to un-fix it again. - Add a patch to drop remote device references in DT graph parsing - Split of_node refcount fixing patch, fix a typo in the comment. - Add Reviewed-by tags from Mathieu. - Drop patches picked up for 4.18-rc series Changes since RFC: - Fixed style issues - Fix an existing memory leak coresight_register (Found in code update) - Fix missing of_node_put() in the existing driver (Reported-by Mathieu) - Update the existing dts in kernel tree. Suzuki K Poulose (10): coresight: Document error handling in coresight_register coresight: platform: Refactor graph endpoint parsing coresight: platform: Fix refcounting for graph nodes coresight: platform: Fix leaking device reference coresight: Fix remote endpoint parsing coresight: Add helper to check if the endpoint is input coresight: platform: Cleanup coresight connection handling coresight: dts: Document usage of graph bindings coresight: Cleanup coresight DT bindings dts: juno: Update coresight bindings for hw port .../devicetree/bindings/arm/coresight.txt | 95 ++++---- arch/arm64/boot/dts/arm/juno-base.dtsi | 161 ++++++------- arch/arm64/boot/dts/arm/juno-cs-r1r2.dtsi | 52 ++-- arch/arm64/boot/dts/arm/juno.dts | 13 +- drivers/hwtracing/coresight/coresight.c | 35 +-- drivers/hwtracing/coresight/of_coresight.c | 262 ++++++++++++++------- include/linux/coresight.h | 9 +- 7 files changed, 353 insertions(+), 274 deletions(-) -- 2.7.4

7 years, 7 months

[PATCH v2 00/10] coresight: perf: Support for tmc-etr backed buffers

by Suzuki K Poulose

This series adds the support for using the tmc-etr in perf mode for storing the trace to system RAM. The ETR uses a separate buffer (double buffering) for storing the trace. This is copied back to the ring buffer when the event is stopped. We try to match the ETR buffer to the larger of perf ring buffer or the size configured for the ETR via sysfs. This allows tuning the buffer size to prevent overflows and loosing trace data, as we don't have overflow interrupt support (yet). Applies on coresight/next Changes since v1 : - Fix path for each CPU where the event might be recorded. - Handle errors in enabling source - Remove set_buffer callback to avoid complicating the error handling. - Fix a bug in handling sysfs mode specific buffers Changes since [0] : - Drop buffer rotation logic for etr-buf - Do not use perf ring buffer. (Add support later) - Fix handling of sink, preventing mixed modes of operation. [0] - TMC ETR perf support - http://lists.infradead.org/pipermail/linux-arm-kernel/2018-May/574875.html Suzuki K Poulose (10): coresight: Fix handling of sinks coresight: perf: Fix per cpu path management coresight: perf: Disable trace path upon source error coresight: tmc-etr: Handle driver mode specific ETR buffers coresight: tmc-etr: Relax collection of trace from sysfs mode coresight: Convert driver messages to dev_dbg coresight: perf: Remove reset_buffer call back for sinks coresight: perf: Add helper to retrieve sink configuration coresight: perf: Remove set_buffer call back coresight: etm-perf: Add support for ETR backend .../coresight/coresight-dynamic-replicator.c | 4 +- drivers/hwtracing/coresight/coresight-etb10.c | 84 ++---- drivers/hwtracing/coresight/coresight-etm-perf.c | 91 +++--- drivers/hwtracing/coresight/coresight-etm-perf.h | 26 ++ drivers/hwtracing/coresight/coresight-etm3x.c | 4 +- drivers/hwtracing/coresight/coresight-etm4x.c | 4 +- drivers/hwtracing/coresight/coresight-funnel.c | 4 +- drivers/hwtracing/coresight/coresight-priv.h | 2 +- drivers/hwtracing/coresight/coresight-replicator.c | 4 +- drivers/hwtracing/coresight/coresight-stm.c | 4 +- drivers/hwtracing/coresight/coresight-tmc-etf.c | 94 +++--- drivers/hwtracing/coresight/coresight-tmc-etr.c | 327 ++++++++++++++++++--- drivers/hwtracing/coresight/coresight-tmc.c | 4 +- drivers/hwtracing/coresight/coresight-tmc.h | 4 + drivers/hwtracing/coresight/coresight-tpiu.c | 6 +- drivers/hwtracing/coresight/coresight.c | 31 +- include/linux/coresight.h | 12 +- 17 files changed, 473 insertions(+), 232 deletions(-) -- 2.7.4

7 years, 7 months

[PATCH 0/6] coresight: perf: Support for tmc-etr backed buffers

by Suzuki K Poulose

7 years, 8 months

[RFC PATCH 0/8] coresight: Update device tree bindings

by Suzuki K Poulose

Coresight uses DT graph bindings to describe the connections of the components. However we have some undocumented usage of the bindings to describe some of the properties of the connections. The coresight driver needs to know the hardware ports invovled in the connection and the direction of data flow to effectively manage the trace sessions. So far we have relied on the "port" address (as described by the generic graph bindings) to represent the hardware port of the component for a connection. The hardware uses separate numbering scheme for input and output ports, which implies, we could have two different (input and output) ports with the same port number. This could create problems in the graph bindings where the label of the port wouldn't match the address. e.g, with the existing bindings we get : port@0{ // Output port 0 reg = <0>; ... }; port@1{ reg = <0>; // Input port 0 endpoint { slave-mode; ... }; }; With the new enforcement in the DT rules, mismatches in label and address are not allowed (as see in the case for port@1). So, we need a new mechanism to describe the hardware port number reliably. Also, we relied on an undocumented "slave-mode" property (see the above example) to indicate if the port is an input port. Let us formalise and switch to a new property to describe the direction of data flow. There were three options considered for the hardware port number scheme: 1) Use natural ordering in the DT to infer the hardware port number. i.e, Mandate that the all ports are listed in the DT and in the ascending order for each class (input and output respectively). Pros : - We don't need new properties and if the existing DTS list them in order (which most of them do), they work out of the box. Cons : - We must list all the ports even if the system cannot/shouldn't use it. - It is prone to human errors (if the order is not kept). 2) Use an explicit property to list both the direction and the hw port number and direction. Define "coresight,hwid" as 2 member array of u32, where the members are port number and the direction respectively. e.g port@0{ reg = <0>; endpoint { coresight,hwid = <0 1>; // Port # 0, Output } }; port@1{ reg = <1>; endpoint { coresight,hwid = <0 0>; // Port # 0, Input }; }; Pros: - The bindings are formal but not so reader friendly and could potentially lead to human errors. Cons: - Backward compatiblity is lost. 3) Use explicit properties (implemented in the series) for the hardware port id and direction. We define a new property "coresight,hwid" for each endpoint in coresight devices to specify the hardware port number explicitly. Also use a separate property "direction" to specify the direction of the data flow. e.g, port@0{ reg = <0>; endpoint { direction = <1>; // Output coresight,hwid = <0>; // Port # 0 } }; port@1{ reg = <1>; endpoint { direction = <0>; // Input coresight,hwid = <0>; // Port # 0 }; }; Pros: - The bindings are formal and reader friendly, and less prone to errors. Cons: - Backward compatibility is lost. This series achieves implements Option (3) listed above while still retaining the backward compatibility. The driver now issues a warning (once) when it encounters the old bindings. It also cleans up the platform parsing code to reduce the memory usage by reusing the platform description. The series also includes the changes for Juno platform as an example. If there are no objections to the approach, I could post the series, converting all the in-kernel DTS to the new binding. Suzuki K Poulose (8): dts: binding: coresight: Document graph bindings coresight: Fix remote endpoint parsing coresight: Cleanup platform description data coresight: platform: Cleanup coresight connection handling coresight: Handle errors in finding input/output ports dts: coresight: Clean up the device tree graph bindings dts: coresight: Define new bindings for direction of data flow dts: juno: Update coresight bindings for hw port .../devicetree/bindings/arm/coresight.txt | 52 ++++++++-- arch/arm64/boot/dts/arm/juno-base.dtsi | 82 +++++++++++---- arch/arm64/boot/dts/arm/juno.dts | 5 +- drivers/hwtracing/coresight/coresight.c | 28 ++---- drivers/hwtracing/coresight/of_coresight.c | 111 ++++++++++++--------- include/linux/coresight.h | 11 +- 6 files changed, 181 insertions(+), 108 deletions(-) -- 2.7.4

7 years, 8 months

Jump to page:

2026

2025

2024

2023

2022

2021

2020

2019

2018

2017

2016

2015

CoreSight