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From: Saurav Sachidanand <sauravsc@amazon.com>
To: Will Deacon <will@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>,
	Besar Wicaksono <bwicaksono@nvidia.com>,
	Ilkka Koskinen <ilkka@os.amperecomputing.com>,
	Jonathan Hunter <jonathanh@nvidia.com>,
	<linux-arm-kernel@lists.infradead.org>,
	<linux-perf-users@vger.kernel.org>,
	<linux-kernel@vger.kernel.org>, <aghayev@amazon.com>,
	<juew@amazon.com>, Saurav Sachidanand <sauravsc@amazon.com>
Subject: [PATCH 3/3] perf/arm_cspmu: nvidia: fix BDF calculation examples in PCIE PMU docs
Date: Mon, 11 May 2026 21:09:05 +0000	[thread overview]
Message-ID: <20260511210905.91917-2-sauravsc@amazon.com> (raw)
In-Reply-To: <20260511210905.91917-1-sauravsc@amazon.com>

The BDF hex values in the documentation examples are inconsistent with
the stated formula (bus << 8) + (device << 3) + (function):

  - BDF 27:01.1: documented as 0x2781, correct value is 0x2709
    (0x27 << 8) + (0x01 << 3) + 0x1 = 0x2709
  - BDF 01:01.0: documented as 0x0180, correct value is 0x0108
    (0x01 << 8) + (0x01 << 3) + 0x0 = 0x0108

It appears (device << 7) was used instead of (device << 3) when
computing the example values.

Fixes: bf585ba14726 ("perf/arm_cspmu: nvidia: Add Tegra410 PCIE PMU")
Signed-off-by: Saurav Sachidanand <sauravsc@amazon.com>
---
 Documentation/admin-guide/perf/nvidia-tegra410-pmu.rst | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Documentation/admin-guide/perf/nvidia-tegra410-pmu.rst b/Documentation/admin-guide/perf/nvidia-tegra410-pmu.rst
index 0656223b61d47..24f0e801d7b80 100644
--- a/Documentation/admin-guide/perf/nvidia-tegra410-pmu.rst
+++ b/Documentation/admin-guide/perf/nvidia-tegra410-pmu.rst
@@ -170,7 +170,7 @@ The list of event filters:
     devices in root port 0 to 3.
   * src_bdf: the BDF that will be monitored. This is a 16-bit value that
     follows formula: (bus << 8) + (device << 3) + (function). For example, the
-    value of BDF 27:01.1 is 0x2781.
+    value of BDF 27:01.1 is 0x2709.
   * src_bdf_en: enable the BDF filter. If this is set, the BDF filter value in
     "src_bdf" is used to filter the traffic.
 
@@ -215,7 +215,7 @@ Example usage:
 * Count event id 0x4 from BDF 01:01.0 of PCIE RC-4 on socket 0 targeting all
   destinations::
 
-    perf stat -a -e nvidia_pcie_pmu_0_rc_4/event=0x4,src_bdf=0x0180,src_bdf_en=0x1/
+    perf stat -a -e nvidia_pcie_pmu_0_rc_4/event=0x4,src_bdf=0x0108,src_bdf_en=0x1/
 
 .. _NVIDIA_T410_PCIE_PMU_RC_Mapping_Section:
 
-- 
2.47.3


      reply	other threads:[~2026-05-11 21:09 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-05-11 21:09 [PATCH 2/3] perf/arm_cspmu: nvidia: handle empty resource list in PCIE-TGT init Saurav Sachidanand
2026-05-11 21:09 ` Saurav Sachidanand [this message]

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