linux-kernel - [PATCHv14 9/9] soc: qcom: geni: Disable MMIO tracing for GENI SE

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Date:   Wed, 4 May 2022 16:58:28 +0530
From:   Sai Prakash Ranjan <quic_saipraka@...cinc.com>
To:     <arnd@...db.de>, <catalin.marinas@....com>, <rostedt@...dmis.org>
CC:     <gregkh@...uxfoundation.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-arm-msm@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <maz@...nel.org>, <quic_psodagud@...cinc.com>,
        <quic_tsoni@...cinc.com>, <will@...nel.org>,
        Sai Prakash Ranjan <quic_saipraka@...cinc.com>,
        "Bjorn Andersson" <bjorn.andersson@...aro.org>
Subject: [PATCHv14 9/9] soc: qcom: geni: Disable MMIO tracing for GENI SE

Disable MMIO tracing for GENI SE driver to prevent excessive
logging. Any access over serial console would involve a lot of
TX and RX register accesses (and few others), so these MMIO
read/write trace events in these drivers cause a lot of unwanted
noise because of the high frequency of such operations and it is
not very useful tracing these events for such drivers.
Given we want to enable these trace events on development devices
(maybe not production devices) where performance also really
matters so that we don't regress other components by wasting CPU
cycles and memory collecting these traces, it makes more sense to
disable these  traces from such drivers.

Also another reason to disable these traces would be to prevent
recursive tracing when we display the trace buffer containing
these MMIO trace events since writing onto serial console would
further record MMIO traces.

Cc: Bjorn Andersson <bjorn.andersson@...aro.org>
Signed-off-by: Sai Prakash Ranjan <quic_saipraka@...cinc.com>
---
 drivers/soc/qcom/qcom-geni-se.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/soc/qcom/qcom-geni-se.c b/drivers/soc/qcom/qcom-geni-se.c
index 28a8c0dda66c..a0ceeede450f 100644
--- a/drivers/soc/qcom/qcom-geni-se.c
+++ b/drivers/soc/qcom/qcom-geni-se.c
@@ -1,6 +1,9 @@
 // SPDX-License-Identifier: GPL-2.0
 // Copyright (c) 2017-2018, The Linux Foundation. All rights reserved.

+/* Disable MMIO tracing to prevent excessive logging of unwanted MMIO traces */
+#define __DISABLE_TRACE_MMIO__
+
 #include <linux/acpi.h>
 #include <linux/clk.h>
 #include <linux/slab.h>
-- 
2.33.1