mtd: docg4: fix status polling loop

The loop that polls the status register waiting for an operation to complete
foolishly bases the timeout simply on the number of loop iterations that have
ocurred.  When I increased the processor clock speed, timeouts started to appear
for long block erasure operations.  This patch measures the timeout using
jiffies.
Signed-off-by: NMike Dunn <mikedunn@newsguy.com>
Signed-off-by: NBrian Norris <computersforpeace@gmail.com>

drivers/mtd/nand/docg4.c

@@ -44,6 +44,7 @@
 #include <linux/mtd/nand.h>
 #include <linux/bch.h>
 #include <linux/bitrev.h>
+#include <linux/jiffies.h>
 
 /*
  * In "reliable mode" consecutive 2k pages are used in parallel (in some
@@ -269,7 +270,7 @@ static int poll_status(struct docg4_priv *doc)
 	 */
 
 	uint16_t flash_status;
-	unsigned int timeo;
+	unsigned long timeo;
 	void __iomem *docptr = doc->virtadr;
 
 	dev_dbg(doc->dev, "%s...\n", __func__);
@@ -277,22 +278,18 @@ static int poll_status(struct docg4_priv *doc)
 	/* hardware quirk requires reading twice initially */
 	flash_status = readw(docptr + DOC_FLASHCONTROL);
 
-	timeo = 1000;
+	timeo = jiffies + msecs_to_jiffies(200); /* generous timeout */
 	do {
 		cpu_relax();
 		flash_status = readb(docptr + DOC_FLASHCONTROL);
-	} while (!(flash_status & DOC_CTRL_FLASHREADY) && --timeo);
+	} while (!(flash_status & DOC_CTRL_FLASHREADY) &&
+		 time_before(jiffies, timeo));
 
-
-	if (!timeo) {
+	if (unlikely(!(flash_status & DOC_CTRL_FLASHREADY))) {
 		dev_err(doc->dev, "%s: timed out!\n", __func__);
 		return NAND_STATUS_FAIL;
 	}
 
-	if (unlikely(timeo < 50))
-		dev_warn(doc->dev, "%s: nearly timed out; %d remaining\n",
-			 __func__, timeo);
-
 	return 0;
 }