From: Olivier Sobrie <olivier@sobrie.be>
Date: Mon, 26 Mar 2012 19:47:18 +0000 (+0200)
Subject: i2c-isch: Decrease delay in command completion check loop
X-Git-Tag: firefly_0821_release~3680^2~3225^2~5
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=b3240e68c05deef2df28db9fc0eea4c277f76494;p=firefly-linux-kernel-4.4.55.git

i2c-isch: Decrease delay in command completion check loop

Generally it is not needed to wait for 1 msec, the SMBus get often ready
in less than 200 usecs.

msleep(1) can wait up to 20 msecs... It has a significant impact when
there is a burst of transactions on the bus.

Signed-off-by: Olivier Sobrie <olivier@sobrie.be>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
---

diff --git a/drivers/i2c/busses/i2c-isch.c b/drivers/i2c/busses/i2c-isch.c
index 6561d275b8cf..f90a6057508d 100644
--- a/drivers/i2c/busses/i2c-isch.c
+++ b/drivers/i2c/busses/i2c-isch.c
@@ -47,7 +47,7 @@
 #define SMBBLKDAT	(0x20 + sch_smba)
 
 /* Other settings */
-#define MAX_TIMEOUT	500
+#define MAX_RETRIES	5000
 
 /* I2C constants */
 #define SCH_QUICK		0x00
@@ -68,7 +68,7 @@ static int sch_transaction(void)
 {
 	int temp;
 	int result = 0;
-	int timeout = 0;
+	int retries = 0;
 
 	dev_dbg(&sch_adapter.dev, "Transaction (pre): CNT=%02x, CMD=%02x, "
 		"ADD=%02x, DAT0=%02x, DAT1=%02x\n", inb(SMBHSTCNT),
@@ -100,12 +100,12 @@ static int sch_transaction(void)
 	outb(inb(SMBHSTCNT) | 0x10, SMBHSTCNT);
 
 	do {
-		msleep(1);
+		usleep_range(100, 200);
 		temp = inb(SMBHSTSTS) & 0x0f;
-	} while ((temp & 0x08) && (timeout++ < MAX_TIMEOUT));
+	} while ((temp & 0x08) && (retries++ < MAX_RETRIES));
 
 	/* If the SMBus is still busy, we give up */
-	if (timeout > MAX_TIMEOUT) {
+	if (retries > MAX_RETRIES) {
 		dev_err(&sch_adapter.dev, "SMBus Timeout!\n");
 		result = -ETIMEDOUT;
 	}