From patchwork Fri Aug 18 11:20:49 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Anshuman Khandual X-Patchwork-Id: 13357767 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 5DD48C001DE for ; Fri, 18 Aug 2023 11:21:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=0sGsgs0Frx86HVo6y3L/+TnIY7i1+RHvZ3HvNPUPZd4=; b=TqytUMz14c1dHg E1ymI7YJeN/FBxfKz8FXpV8uf03fCo3OuECgMfl6W6JLoqenwrLV3YcG5zmEk2up1IeBISJgPkxZK l6IbIqVo6nZW29ZLxYf5ajrzAuWyyo/b+iU+3xgZmbxEhmfrPu5hs4cMuVFSPiXi/xzIXnef7WIRU 7FxK1rqyvG+wKoPI7G897jV0/pFYyfM4osEXy5P5RLMa6aj7XMqdNZ1jMo1+YMionHg0Bk+NPiVVH DAyWO32vOqmaHnpHWNvNMG6M+mAvcoqDhcKgiQKcna+Othjn+ZQdxQGVuoRRCEHC8zjrJ1h+LXow7 o8T/B31zsNiq0tVbu9IQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qWxXd-008dp1-0q; Fri, 18 Aug 2023 11:21:21 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qWxXT-008djb-1j for linux-arm-kernel@lists.infradead.org; Fri, 18 Aug 2023 11:21:13 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 140B51007; Fri, 18 Aug 2023 04:21:50 -0700 (PDT) Received: from a077893.arm.com (unknown [10.163.55.189]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 4FEA03F762; Fri, 18 Aug 2023 04:21:05 -0700 (PDT) From: Anshuman Khandual To: linux-arm-kernel@lists.infradead.org, suzuki.poulose@arm.com Cc: Anshuman Khandual , Catalin Marinas , Will Deacon , Mike Leach , James Clark , Leo Yan , Jonathan Corbet , linux-doc@vger.kernel.org, coresight@lists.linaro.org, linux-kernel@vger.kernel.org Subject: [PATCH V4 1/3] coresight: etm: Override TRCIDR3.CCITMIN on errata affected cpus Date: Fri, 18 Aug 2023 16:50:49 +0530 Message-Id: <20230818112051.594986-2-anshuman.khandual@arm.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20230818112051.594986-1-anshuman.khandual@arm.com> References: <20230818112051.594986-1-anshuman.khandual@arm.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230818_042111_670663_58F83450 X-CRM114-Status: GOOD ( 15.35 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org This work arounds errata 1490853 on Cortex-A76, and Neoverse-N1, errata 1491015 on Cortex-A77, errata 1502854 on Cortex-X1, and errata 1619801 on Neoverse-V1, based affected cpus, where software read for TRCIDR3.CCITMIN field in ETM gets an wrong value. If software uses the value returned by the TRCIDR3.CCITMIN register field, then it will limit the range which could be used for programming the ETM. In reality, the ETM could be programmed with a much smaller value than what is indicated by the TRCIDR3.CCITMIN field and still function correctly. If software reads the TRCIDR3.CCITMIN register field, corresponding to the instruction trace counting minimum threshold, observe the value 0x100 or a minimum cycle count threshold of 256. The correct value should be 0x4 or a minimum cycle count threshold of 4. This work arounds the problem via storing 4 in drvdata->ccitmin on affected systems where the TRCIDR3.CCITMIN has been 256, thus preserving cycle count threshold granularity. These errata information has been updated in arch/arm64/silicon-errata.rst, but without their corresponding configs because these have been implemented directly in the driver. Cc: Catalin Marinas Cc: Will Deacon Cc: Suzuki K Poulose Cc: Mike Leach Cc: James Clark Cc: Jonathan Corbet Cc: linux-doc@vger.kernel.org Cc: coresight@lists.linaro.org Cc: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Anshuman Khandual --- Documentation/arch/arm64/silicon-errata.rst | 10 ++++++ .../coresight/coresight-etm4x-core.c | 36 +++++++++++++++++++ 2 files changed, 46 insertions(+) diff --git a/Documentation/arch/arm64/silicon-errata.rst b/Documentation/arch/arm64/silicon-errata.rst index bedd3a1d7b42..b08f33eda5f1 100644 --- a/Documentation/arch/arm64/silicon-errata.rst +++ b/Documentation/arch/arm64/silicon-errata.rst @@ -107,6 +107,10 @@ stable kernels. +----------------+-----------------+-----------------+-----------------------------+ | ARM | Cortex-A76 | #1463225 | ARM64_ERRATUM_1463225 | +----------------+-----------------+-----------------+-----------------------------+ +| ARM | Cortex-A76 | #1490853 | N/A | ++----------------+-----------------+-----------------+-----------------------------+ +| ARM | Cortex-A77 | #1491015 | N/A | ++----------------+-----------------+-----------------+-----------------------------+ | ARM | Cortex-A77 | #1508412 | ARM64_ERRATUM_1508412 | +----------------+-----------------+-----------------+-----------------------------+ | ARM | Cortex-A510 | #2051678 | ARM64_ERRATUM_2051678 | @@ -125,6 +129,8 @@ stable kernels. +----------------+-----------------+-----------------+-----------------------------+ | ARM | Cortex-A715 | #2645198 | ARM64_ERRATUM_2645198 | +----------------+-----------------+-----------------+-----------------------------+ +| ARM | Cortex-X1 | #1502854 | N/A | ++----------------+-----------------+-----------------+-----------------------------+ | ARM | Cortex-X2 | #2119858 | ARM64_ERRATUM_2119858 | +----------------+-----------------+-----------------+-----------------------------+ | ARM | Cortex-X2 | #2224489 | ARM64_ERRATUM_2224489 | @@ -133,6 +139,8 @@ stable kernels. +----------------+-----------------+-----------------+-----------------------------+ | ARM | Neoverse-N1 | #1349291 | N/A | +----------------+-----------------+-----------------+-----------------------------+ +| ARM | Neoverse-N1 | #1490853 | N/A | ++----------------+-----------------+-----------------+-----------------------------+ | ARM | Neoverse-N1 | #1542419 | ARM64_ERRATUM_1542419 | +----------------+-----------------+-----------------+-----------------------------+ | ARM | Neoverse-N2 | #2139208 | ARM64_ERRATUM_2139208 | @@ -141,6 +149,8 @@ stable kernels. +----------------+-----------------+-----------------+-----------------------------+ | ARM | Neoverse-N2 | #2253138 | ARM64_ERRATUM_2253138 | +----------------+-----------------+-----------------+-----------------------------+ +| ARM | Neoverse-V1 | #1619801 | N/A | ++----------------+-----------------+-----------------+-----------------------------+ | ARM | MMU-500 | #841119,826419 | N/A | +----------------+-----------------+-----------------+-----------------------------+ | ARM | MMU-600 | #1076982,1209401| N/A | diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c index 7e307022303a..591fab73ee79 100644 --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c @@ -1131,6 +1131,39 @@ static void cpu_detect_trace_filtering(struct etmv4_drvdata *drvdata) drvdata->trfcr = trfcr; } +/* + * The following errata on applicable cpu ranges, affect the CCITMIN filed + * in TCRIDR3 register. Software read for the field returns 0x100 limiting + * the cycle threshold granularity, where as the right value should have + * been 0x4, which is well supported in the hardware. + */ +static struct midr_range etm_wrong_ccitmin_cpus[] = { + /* Erratum #1490853 - Cortex-A76 */ + MIDR_RANGE(MIDR_CORTEX_A76, 0, 0, 4, 0), + /* Erratum #1490853 - Neoverse-N1 */ + MIDR_RANGE(MIDR_NEOVERSE_N1, 0, 0, 4, 0), + /* Erratum #1491015 - Cortex-A77 */ + MIDR_RANGE(MIDR_CORTEX_A77, 0, 0, 1, 0), + /* Erratum #1502854 - Cortex-X1 */ + MIDR_REV(MIDR_CORTEX_X1, 0, 0), + /* Erratum #1619801 - Neoverse-V1 */ + MIDR_REV(MIDR_NEOVERSE_V1, 0, 0), + {}, +}; + +static bool etm4_core_reads_wrong_ccitmin(struct etmv4_drvdata *drvdata) +{ + /* + * Erratum affected cpus will read 256 as the minimum + * instruction trace cycle counting threshold where as + * the correct value should be 4 instead. Override the + * recorded value for 'drvdata->ccitmin' to workaround + * this problem. + */ + return is_midr_in_range_list(read_cpuid_id(), etm_wrong_ccitmin_cpus) && + (drvdata->ccitmin == 256); +} + static void etm4_init_arch_data(void *info) { u32 etmidr0; @@ -1195,6 +1228,9 @@ static void etm4_init_arch_data(void *info) etmidr3 = etm4x_relaxed_read32(csa, TRCIDR3); /* CCITMIN, bits[11:0] minimum threshold value that can be programmed */ drvdata->ccitmin = FIELD_GET(TRCIDR3_CCITMIN_MASK, etmidr3); + if (etm4_core_reads_wrong_ccitmin(drvdata)) + drvdata->ccitmin = 4; + /* EXLEVEL_S, bits[19:16] Secure state instruction tracing */ drvdata->s_ex_level = FIELD_GET(TRCIDR3_EXLEVEL_S_MASK, etmidr3); drvdata->config.s_ex_level = drvdata->s_ex_level; From patchwork Fri Aug 18 11:20:50 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Anshuman Khandual X-Patchwork-Id: 13357768 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 09195C678DC for ; Fri, 18 Aug 2023 11:21:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=SarxEQV7gDaMXX+8/2Do+ukJVKILUuhxhJBlZYS0FhA=; b=Dt4RUqPbbijiGz 9xrOEp2ctQLvD/2Nl8SItgmOwI/YIE+bnVHH6Ou04YOl5Lepqeo0XrQFk1LLU6x559Pf58y2MRX1g zmB2DDWoYAaSv2aqjvdiPai7uWIbbxRSxKNb2texZDkBc3NQNpAuGhBdPqumnAFHPsrDpHnI5pMtd EVpTrSBXn54qNo3gAuE9ig1j7tmD2I6rJ2w9lUOYF20dHzSIpC5tLU5P2KMzsEuuMWca+rVc0nbxE VFTagIzvUMehfs9/lEqkMCgQoXLgzqkrMMnX0NhHUyPCzBZciseUxkTUAetumx5FMT6NK37ZMp7vK SkaIlW0wF8vg9u/FuPgg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qWxXd-008dpP-2x; Fri, 18 Aug 2023 11:21:21 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qWxXX-008dlR-1v for linux-arm-kernel@lists.infradead.org; Fri, 18 Aug 2023 11:21:17 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 64C211063; Fri, 18 Aug 2023 04:21:55 -0700 (PDT) Received: from a077893.arm.com (unknown [10.163.55.189]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 338183F762; Fri, 18 Aug 2023 04:21:09 -0700 (PDT) From: Anshuman Khandual To: linux-arm-kernel@lists.infradead.org, suzuki.poulose@arm.com Cc: Anshuman Khandual , Catalin Marinas , Will Deacon , Mike Leach , James Clark , Leo Yan , Jonathan Corbet , linux-doc@vger.kernel.org, coresight@lists.linaro.org, linux-kernel@vger.kernel.org Subject: [PATCH V4 2/3] coresight: etm: Make cycle count threshold user configurable Date: Fri, 18 Aug 2023 16:50:50 +0530 Message-Id: <20230818112051.594986-3-anshuman.khandual@arm.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20230818112051.594986-1-anshuman.khandual@arm.com> References: <20230818112051.594986-1-anshuman.khandual@arm.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230818_042115_998737_7E876956 X-CRM114-Status: GOOD ( 15.02 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Cycle counting is enabled, when requested and supported but with a default threshold value ETM_CYC_THRESHOLD_DEFAULT i.e 0x100 getting into TRCCCCTLR, representing the minimum interval between cycle count trace packets. This makes cycle threshold user configurable, from the user space via perf event attributes. Although it falls back using ETM_CYC_THRESHOLD_DEFAULT, in case no explicit request. As expected it creates a sysfs file as well. /sys/bus/event_source/devices/cs_etm/format/cc_threshold New 'cc_threshold' uses 'event->attr.config3' as no more space is available in 'event->attr.config1' or 'event->attr.config2'. Cc: Suzuki K Poulose Cc: Mike Leach Cc: James Clark Cc: Leo Yan Cc: coresight@lists.linaro.org Cc: linux-arm-kernel@lists.infradead.org Cc: linux-doc@vger.kernel.org Cc: linux-kernel@vger.kernel.org Reviewed-by: Mike Leach Signed-off-by: Anshuman Khandual --- drivers/hwtracing/coresight/coresight-etm-perf.c | 2 ++ drivers/hwtracing/coresight/coresight-etm4x-core.c | 12 ++++++++++-- 2 files changed, 12 insertions(+), 2 deletions(-) diff --git a/drivers/hwtracing/coresight/coresight-etm-perf.c b/drivers/hwtracing/coresight/coresight-etm-perf.c index 5ca6278baff4..09f75dffae60 100644 --- a/drivers/hwtracing/coresight/coresight-etm-perf.c +++ b/drivers/hwtracing/coresight/coresight-etm-perf.c @@ -68,6 +68,7 @@ PMU_FORMAT_ATTR(preset, "config:0-3"); PMU_FORMAT_ATTR(sinkid, "config2:0-31"); /* config ID - set if a system configuration is selected */ PMU_FORMAT_ATTR(configid, "config2:32-63"); +PMU_FORMAT_ATTR(cc_threshold, "config3:0-11"); /* @@ -101,6 +102,7 @@ static struct attribute *etm_config_formats_attr[] = { &format_attr_preset.attr, &format_attr_configid.attr, &format_attr_branch_broadcast.attr, + &format_attr_cc_threshold.attr, NULL, }; diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c index 591fab73ee79..3193dafa7618 100644 --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c @@ -635,7 +635,7 @@ static int etm4_parse_event_config(struct coresight_device *csdev, struct etmv4_config *config = &drvdata->config; struct perf_event_attr *attr = &event->attr; unsigned long cfg_hash; - int preset; + int preset, cc_threshold; /* Clear configuration from previous run */ memset(config, 0, sizeof(struct etmv4_config)); @@ -658,7 +658,15 @@ static int etm4_parse_event_config(struct coresight_device *csdev, if (attr->config & BIT(ETM_OPT_CYCACC)) { config->cfg |= TRCCONFIGR_CCI; /* TRM: Must program this for cycacc to work */ - config->ccctlr = ETM_CYC_THRESHOLD_DEFAULT; + cc_threshold = attr->config3 & ETM_CYC_THRESHOLD_MASK; + if (cc_threshold) { + if (cc_threshold < drvdata->ccitmin) + config->ccctlr = drvdata->ccitmin; + else + config->ccctlr = cc_threshold; + } else { + config->ccctlr = ETM_CYC_THRESHOLD_DEFAULT; + } } if (attr->config & BIT(ETM_OPT_TS)) { /* From patchwork Fri Aug 18 11:20:51 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Anshuman Khandual X-Patchwork-Id: 13357769 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id E0431C71136 for ; Fri, 18 Aug 2023 11:21:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=JvoR8OiYRzq4J2A6VDj2Dn9SMPoB/v2sKHjPKltFwLQ=; b=QOPa7FgiFMO68M 9Wd9bdC67hMUUgQI3CIP4e2gH8LdrTRyNJFhloy2wXJD0MlbdkcWOLM8zjNGXohe9ZwgxX5Fqo2nc 1BCtP0SE8lw1IzhRE1lgH9d2mAbumul+w6Q90Dl8SHjxt6++oIBYlgFA/sRzxw8ix95/qHoIhF0bB iaQ/XmVUQ303RFz1PRh3vxgO5rwWhIsnB+bA0ExvpXxhw4cA73swt0XYIy4U6KA5kdvGpuZYGzY7O 67px3vlCWJYLgX5OFpgEw70asOe/j7QQt5LLW7410Ooa6A44Nnbcz+LElTHWYsDsARnhs+/8UpI9z nsgUSCCTMqDVNf71lM2w==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qWxXp-008dy4-2x; Fri, 18 Aug 2023 11:21:33 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qWxXc-008doS-38 for linux-arm-kernel@lists.infradead.org; Fri, 18 Aug 2023 11:21:22 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 5CBC3D75; Fri, 18 Aug 2023 04:22:00 -0700 (PDT) Received: from a077893.arm.com (unknown [10.163.55.189]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 8A7B13F762; Fri, 18 Aug 2023 04:21:15 -0700 (PDT) From: Anshuman Khandual To: linux-arm-kernel@lists.infradead.org, suzuki.poulose@arm.com Cc: Anshuman Khandual , Catalin Marinas , Will Deacon , Mike Leach , James Clark , Leo Yan , Jonathan Corbet , linux-doc@vger.kernel.org, coresight@lists.linaro.org, linux-kernel@vger.kernel.org Subject: [PATCH V4 3/3] Documentation: coresight: Add cc_threshold tunable Date: Fri, 18 Aug 2023 16:50:51 +0530 Message-Id: <20230818112051.594986-4-anshuman.khandual@arm.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20230818112051.594986-1-anshuman.khandual@arm.com> References: <20230818112051.594986-1-anshuman.khandual@arm.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230818_042121_068384_65D371F9 X-CRM114-Status: GOOD ( 10.13 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org This updates config option to include 'cc_threshold' tunable value. Cc: Suzuki K Poulose Cc: Mike Leach Cc: James Clark Cc: Jonathan Corbet Cc: coresight@lists.linaro.org Cc: linux-arm-kernel@lists.infradead.org Cc: linux-doc@vger.kernel.org Cc: linux-kernel@vger.kernel.org Reviewed by: Mike Leach Signed-off-by: Anshuman Khandual --- Documentation/trace/coresight/coresight.rst | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/Documentation/trace/coresight/coresight.rst b/Documentation/trace/coresight/coresight.rst index 4a71ea6cb390..ce55adb80b82 100644 --- a/Documentation/trace/coresight/coresight.rst +++ b/Documentation/trace/coresight/coresight.rst @@ -624,6 +624,10 @@ They are also listed in the folder /sys/bus/event_source/devices/cs_etm/format/ * - timestamp - Session local version of the system wide setting: :ref:`ETMv4_MODE_TIMESTAMP ` + * - cc_threshold + - Cycle count threshold value. If nothing is provided here or the provided value is 0, then the + default value i.e 0x100 will be used. If provided value is less than minimum cycles threshold + value, as indicated via TRCIDR3.CCITMIN, then the minimum value will be used instead. How to use the STM module -------------------------