i2c-i801: Use usleep_range to wait for command completion

Use usleep_range instead of msleep when waiting for command
completion. Most SMBus commands complete in less than 2 jiffies so
this brings a pleasant performance boost.

Strongly inspired from a similar change by Olivier Sobrie to the
i2c-isch driver.

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

diff --git a/drivers/i2c/busses/i2c-i801.c b/drivers/i2c/busses/i2c-i801.c
index 07d0c95..ae2945a 100644 (file)
--- a/drivers/i2c/busses/i2c-i801.c
+++ b/drivers/i2c/busses/i2c-i801.c
@@ -2,7 +2,7 @@
     Copyright (c) 1998 - 2002  Frodo Looijaard <frodol@dds.nl>,
     Philip Edelbrock <phil@netroedge.com>, and Mark D. Studebaker
     <mdsxyz123@yahoo.com>
-    Copyright (C) 2007, 2008   Jean Delvare <khali@linux-fr.org>
+    Copyright (C) 2007 - 2012  Jean Delvare <khali@linux-fr.org>
     Copyright (C) 2010         Intel Corporation,
                                David Woodhouse <dwmw2@infradead.org>
 
@@ -106,7 +106,7 @@
 #define SMBHSTCNT_KILL         2
 
 /* Other settings */
-#define MAX_TIMEOUT            100
+#define MAX_RETRIES            400
 #define ENABLE_INT9            0       /* set to 0x01 to enable - untested */
 
 /* I801 command constants */
@@ -217,7 +217,7 @@ static int i801_check_post(struct i801_priv *priv, int status, int timeout)
                dev_dbg(&priv->pci_dev->dev, "Terminating the current operation\n");
                outb_p(inb_p(SMBHSTCNT(priv)) | SMBHSTCNT_KILL,
                       SMBHSTCNT(priv));
-               msleep(1);
+               usleep_range(1000, 2000);
                outb_p(inb_p(SMBHSTCNT(priv)) & (~SMBHSTCNT_KILL),
                       SMBHSTCNT(priv));
 
@@ -274,11 +274,11 @@ static int i801_transaction(struct i801_priv *priv, int xact)
 
        /* We will always wait for a fraction of a second! */
        do {
-               msleep(1);
+               usleep_range(250, 500);
                status = inb_p(SMBHSTSTS(priv));
-       } while ((status & SMBHSTSTS_HOST_BUSY) && (timeout++ < MAX_TIMEOUT));
+       } while ((status & SMBHSTSTS_HOST_BUSY) && (timeout++ < MAX_RETRIES));
 
-       result = i801_check_post(priv, status, timeout > MAX_TIMEOUT);
+       result = i801_check_post(priv, status, timeout > MAX_RETRIES);
        if (result < 0)
                return result;
 
@@ -293,12 +293,12 @@ static void i801_wait_hwpec(struct i801_priv *priv)
        int status;
 
        do {
-               msleep(1);
+               usleep_range(250, 500);
                status = inb_p(SMBHSTSTS(priv));
        } while ((!(status & SMBHSTSTS_INTR))
-                && (timeout++ < MAX_TIMEOUT));
+                && (timeout++ < MAX_RETRIES));
 
-       if (timeout > MAX_TIMEOUT)
+       if (timeout > MAX_RETRIES)
                dev_dbg(&priv->pci_dev->dev, "PEC Timeout!\n");
 
        outb_p(status, SMBHSTSTS(priv));
@@ -382,12 +382,12 @@ static int i801_block_transaction_byte_by_byte(struct i801_priv *priv,
                /* We will always wait for a fraction of a second! */
                timeout = 0;
                do {
-                       msleep(1);
+                       usleep_range(250, 500);
                        status = inb_p(SMBHSTSTS(priv));
                } while ((!(status & SMBHSTSTS_BYTE_DONE))
-                        && (timeout++ < MAX_TIMEOUT));
+                        && (timeout++ < MAX_RETRIES));
 
-               result = i801_check_post(priv, status, timeout > MAX_TIMEOUT);
+               result = i801_check_post(priv, status, timeout > MAX_RETRIES);
                if (result < 0)
                        return result;