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mmc: core: Log MMC clock frequency transitions 

Use kernel's ftrace support to capture MMC clock frequency
transitions which can be useful for debugging issues related
to power consumption.

Usage:
mount -t debugfs none /sys/kernel/debug
echo 1 > /sys/kernel/debug/tracing/events/mmc/mmc_clk/enable
cat /sys/kernel/debug/tracing/trace_pipe

Change-Id: I25c4ee39dcbe30e7665902a9f723a5a421b55ca3
Signed-off-by: Sujit Reddy Thumma <sthumma@codeaurora.org>
This commit is contained in:
Sujit Reddy Thumma 2013-02-14 08:13:52 +05:30 committed by Stephen Boyd
parent 51361f9fd5
commit 2b899baf24
3 changed files with 36 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
drivers/mmc/core/core.c
View File

@ -1492,6 +1492,19 @@ void mmc_set_ios(struct mmc_host *host)
if (ios->clock > 0)
mmc_set_ungated(host);
host->ops->set_ios(host, ios);
if (ios->old_rate != ios->clock) {
if (likely(ios->clk_ts)) {
char trace_info[80];
snprintf(trace_info, 80,
"%s: freq_KHz %d --> %d | t = %d",
mmc_hostname(host), ios->old_rate / 1000,
ios->clock / 1000, jiffies_to_msecs(
(long)jiffies - (long)ios->clk_ts));
trace_mmc_clk(trace_info);
}
ios->old_rate = ios->clock;
ios->clk_ts = jiffies;
}
}
EXPORT_SYMBOL(mmc_set_ios);

2
include/linux/mmc/host.h
View File

@ -22,6 +22,8 @@
struct mmc_ios {
unsigned int clock; /* clock rate */
unsigned int old_rate; /* saved clock rate */
unsigned long clk_ts; /* time stamp of last updated clock */
unsigned short vdd;
/* vdd stores the bit number of the selected voltage range from below. */

22
include/trace/events/mmc.h
View File

@ -1,5 +1,6 @@
/*
* Copyright (C) 2013 Google, Inc.
* Copyright (c) 2013, The Linux Foundation. All rights reserved.
*
* This software is licensed under the terms of the GNU General Public
* License version 2, as published by the Free Software Foundation, and
@ -85,7 +86,26 @@ DEFINE_EVENT_CONDITION(mmc_blk_rw_class, mmc_blk_rw_end,
TP_CONDITION(((cmd == MMC_READ_MULTIPLE_BLOCK) ||
(cmd == MMC_WRITE_MULTIPLE_BLOCK)) &&
data));
#endif /* _TRACE_MMC_H */
TRACE_EVENT(mmc_clk,
TP_PROTO(char *print_info),
TP_ARGS(print_info),
TP_STRUCT__entry(
__string(print_info, print_info)
),
TP_fast_assign(
__assign_str(print_info, print_info);
),
TP_printk("%s",
__get_str(print_info)
)
);
#endif /* if !defined(_TRACE_MMC_H) || defined(TRACE_HEADER_MULTI_READ) */
/* This part must be outside protection */
#include <trace/define_trace.h>