From 9a092183816a05f802ce3d4d7815b214413d6ad8 Mon Sep 17 00:00:00 2001
From: Subhash Jadavani <subhashj@codeaurora.org>
Date: Sun, 25 Mar 2012 11:15:41 +0530
Subject: [PATCH] mmc: core: capture performance numbers only when asked

Currently performance numbers are captured for each SDCC
transfers unconditionally which may add the overhead and
could reduce the SDCC read/write throughput numbers.

This change adds additional control for enabling/disabling the
capturing of performance numbers at runtime. We already have sysfs
entry named "perf" for msm sdcc devices. Currently setting this
entry to 0 clears the performance statistics. But now we are
changing the definition of this entry as mentioned below:

Disable performance capturing and clear the performance statistics:
	"echo 0 > /sys/devices/platform/msm_sdcc.<n>/perf"

Enable performance capturing:
	"echo 1 > /sys/devices/platform/msm_sdcc.<n>/perf"

CRs-fixed: 345170
Change-Id: I3ab9288fd87cc8a8ada6c0c3d066cac4f68d79b7
Signed-off-by: Subhash Jadavani <subhashj@codeaurora.org>
---
 drivers/mmc/core/core.c  | 27 ++++++++++++++++-----------
 drivers/mmc/core/host.c  |  9 +++++++--
 include/linux/mmc/host.h |  1 +
 3 files changed, 24 insertions(+), 13 deletions(-)

diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index 48ad5f168b49..f08d160b7954 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -179,17 +179,21 @@ void mmc_request_done(struct mmc_host *host, struct mmc_request *mrq)
 
 		if (mrq->data) {
 #ifdef CONFIG_MMC_PERF_PROFILING
-			diff = ktime_sub(ktime_get(), host->perf.start);
-			if (mrq->data->flags == MMC_DATA_READ) {
-				host->perf.rbytes_drv +=
+			if (host->perf_enable) {
+				diff = ktime_sub(ktime_get(), host->perf.start);
+				if (mrq->data->flags == MMC_DATA_READ) {
+					host->perf.rbytes_drv +=
+							mrq->data->bytes_xfered;
+					host->perf.rtime_drv =
+						ktime_add(host->perf.rtime_drv,
+							diff);
+				} else {
+					host->perf.wbytes_drv +=
 						mrq->data->bytes_xfered;
-				host->perf.rtime_drv =
-					ktime_add(host->perf.rtime_drv, diff);
-			} else {
-				host->perf.wbytes_drv +=
-						 mrq->data->bytes_xfered;
-				host->perf.wtime_drv =
-					ktime_add(host->perf.wtime_drv, diff);
+					host->perf.wtime_drv =
+						ktime_add(host->perf.wtime_drv,
+							diff);
+				}
 			}
 #endif
 			pr_debug("%s:     %d bytes transferred: %d\n",
@@ -313,7 +317,8 @@ static int mmc_start_request(struct mmc_host *host, struct mmc_request *mrq)
 			mrq->stop->mrq = mrq;
 		}
 #ifdef CONFIG_MMC_PERF_PROFILING
-		host->perf.start = ktime_get();
+		if (host->perf_enable)
+			host->perf.start = ktime_get();
 #endif
 	}
 	mmc_host_clk_hold(host);
diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c
index c940ad0bd3fe..38fe00671649 100644
--- a/drivers/mmc/core/host.c
+++ b/drivers/mmc/core/host.c
@@ -651,18 +651,23 @@ set_perf(struct device *dev, struct device_attribute *attr,
 {
 	int64_t value;
 	struct mmc_host *host = dev_get_drvdata(dev);
+
 	sscanf(buf, "%lld", &value);
+	spin_lock(&host->lock);
 	if (!value) {
-		spin_lock(&host->lock);
 		memset(&host->perf, 0, sizeof(host->perf));
-		spin_unlock(&host->lock);
+		host->perf_enable = false;
+	} else {
+		host->perf_enable = true;
 	}
+	spin_unlock(&host->lock);
 
 	return count;
 }
 
 static DEVICE_ATTR(perf, S_IRUGO | S_IWUSR,
 		show_perf, set_perf);
+
 #endif
 
 static struct attribute *dev_attrs[] = {
diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index 30d33363079b..0600ae0d3cb5 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -442,6 +442,7 @@ struct mmc_host {
 		ktime_t wtime_drv;	   /* Wr time  MMC Host  */
 		ktime_t start;
 	} perf;
+	bool perf_enable;
 #endif
 
 	unsigned long		private[0] ____cacheline_aligned;