[PATCH] staging: sm750fb: Replace busy-wait loop with udelay()

[OaroraEtimis <oaroraetimis@gmail.com>]

The empty for-loop in sw_i2c_wait() triggers a -Wunused-but-set-variable
warning and can be optimized away by modern compilers.

Fix this by replacing the unreliable loop with a standard udelay(2).
This also cleans up the unused 'tmp' variable and outdated comments.
Include <linux/delay.h> to resolve the implicit function declaration.

Signed-off-by: OaroraEtimis <OaroraEtimis@gmail.com>
---
 drivers/staging/sm750fb/ddk750_swi2c.c | 20 ++------------------
 1 file changed, 2 insertions(+), 18 deletions(-)

diff --git a/drivers/staging/sm750fb/ddk750_swi2c.c b/drivers/staging/sm750fb/ddk750_swi2c.c
index 0ef8d4ff2ef9..d0aeb917be92 100644
--- a/drivers/staging/sm750fb/ddk750_swi2c.c
+++ b/drivers/staging/sm750fb/ddk750_swi2c.c
@@ -11,6 +11,7 @@
 #include "ddk750_reg.h"
 #include "ddk750_swi2c.h"
 #include "ddk750_power.h"
+#include <linux/delay.h>
 
 /*
  * I2C Software Master Driver:
@@ -80,24 +81,7 @@ static unsigned long sw_i2c_data_gpio_data_dir_reg = GPIO_DATA_DIRECTION;
  */
 static void sw_i2c_wait(void)
 {
-	/* find a bug:
-	 * peekIO method works well before suspend/resume
-	 * but after suspend, peekIO(0x3ce,0x61) & 0x10
-	 * always be non-zero,which makes the while loop
-	 * never finish.
-	 * use non-ultimate for loop below is safe
-	 */
-
-    /* Change wait algorithm to use PCI bus clock,
-     * it's more reliable than counter loop ..
-     * write 0x61 to 0x3ce and read from 0x3cf
-     */
-	int i, tmp;
-
-	for (i = 0; i < 600; i++) {
-		tmp = i;
-		tmp += i;
-	}
+	udelay(2);
 }
 
 /*
-- 
2.47.3